ETH Price: $4,317.25 (+0.94%)

Transaction Decoder

Block:
21779222 at Feb-05-2025 08:52:59 AM +UTC
Transaction Fee:
0.000353331856533742 ETH $1.53
Gas Used:
248,642 Gas / 1.421046551 Gwei

Account State Difference:

  Address   Before After State Difference Code
(MEV Builder: 0x235...cb1)
341.395862458650846452 Eth341.395887322850846452 Eth0.0000248642
0x57bB9146...a9c2f0d9D
0.175684492800396598 Eth
Nonce: 12
0.175331160943862856 Eth
Nonce: 13
0.000353331856533742

Execution Trace

ZeroEx.415565b0( )
  • TransformERC20Feature.transformERC20( inputToken=0x555907a0b5c32DF0fEb35401187aED60a9191D74, outputToken=0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE, inputTokenAmount=123248757273038120000, minOutputTokenAmount=411565993078647, transformations= ) => ( outputTokenAmount=44280108230048337065371510003698035539431158071922791587663103572063451942104 )
    • trumpwifhat.transferFrom( src=0x57bB9146c17eacF2BB91f1b84046fdba9c2f0d9D, dst=0x22F9dCF4647084d6C31b2765F6910cd85C178C18, rawAmount=123248757273038120000 ) => ( True )
      • 0x2415c6d988cefd610d1b024a2df38d2b730f6c5c.02acc130( )
        • 0x1215ca69be7979076d5fd3fd56344752186c8658.02acc130( )
          • WETH9.balanceOf( 0xe4bb64b976bA9Fb3647Af2A958760E8C7d7A85aC ) => ( 101198862824811697199 )
          • FlashWallet.STATICCALL( )
          • 0x2e083137a4e4c47efe9101a5d950abfb53aacee1.8b2ddd63( )
            • 0xca1db1e0846662db16408cb0d78f22ebd24f5b1a.8b2ddd63( )
            • FlashWallet.executeDelegateCall( target=0x2Fd08C1F9FC8406C1D7E3A799A13883a7E7949f0, callData=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
              • FillQuoteTransformer.transform( context=[{name:sender, type:address, order:1, indexed:false, value:0x57bB9146c17eacF2BB91f1b84046fdba9c2f0d9D, valueString:0x57bB9146c17eacF2BB91f1b84046fdba9c2f0d9D}, {name:recipient, type:address, order:2, indexed:false, value:0x57bB9146c17eacF2BB91f1b84046fdba9c2f0d9D, valueString:0x57bB9146c17eacF2BB91f1b84046fdba9c2f0d9D}, {name:data, type:bytes, order:3, indexed:false, value: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valueString: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}] ) => ( magicBytes=System.Byte[] )
                • trumpwifhat.balanceOf( account=0x22F9dCF4647084d6C31b2765F6910cd85C178C18 ) => ( 123248757273038120000 )
                  • 0x2415c6d988cefd610d1b024a2df38d2b730f6c5c.70a08231( )
                    • 0x1215ca69be7979076d5fd3fd56344752186c8658.70a08231( )
                    • EthereumBridgeAdapter.trade( order=[{name:source, type:bytes32, order:1, indexed:false, value:00000000000000000000000000000002556E6973776170563200000000000000, valueString:00000000000000000000000000000002556E6973776170563200000000000000}, {name:takerTokenAmount, type:uint256, order:2, indexed:false, value:123248757273038120000, valueString:123248757273038120000}, {name:makerTokenAmount, type:uint256, order:3, indexed:false, value:416143572374768, valueString:416143572374768}, {name:bridgeData, type:bytes, order:4, indexed:false, value:0x000000000000000000000000F164FC0EC4E93095B804A4795BBE1E041497B92A00000000000000000000000000000000000000000000000000000000000000400000000000000000000000000000000000000000000000000000000000000002000000000000000000000000555907A0B5C32DF0FEB35401187AED60A9191D74000000000000000000000000C02AAA39B223FE8D0A0E5C4F27EAD9083C756CC2, valueString:0x000000000000000000000000F164FC0EC4E93095B804A4795BBE1E041497B92A00000000000000000000000000000000000000000000000000000000000000400000000000000000000000000000000000000000000000000000000000000002000000000000000000000000555907A0B5C32DF0FEB35401187AED60A9191D74000000000000000000000000C02AAA39B223FE8D0A0E5C4F27EAD9083C756CC2}], sellToken=0x555907a0b5c32DF0fEb35401187aED60a9191D74, buyToken=0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2, sellAmount=123248757273038120000 ) => ( boughtAmount=3963877391197344453575983046348115674221700746820753546331534351508065746944 )
                      • trumpwifhat.allowance( account=0x22F9dCF4647084d6C31b2765F6910cd85C178C18, spender=0xf164fC0Ec4E93095b804a4795bBe1e041497b92a ) => ( 0 )
                      • trumpwifhat.approve( spender=0xf164fC0Ec4E93095b804a4795bBe1e041497b92a, rawAmount=115792089237316195423570985008687907853269984665640564039457584007913129639935 ) => ( True )
                        • 0x2415c6d988cefd610d1b024a2df38d2b730f6c5c.5c19a95c( )
                        • UniswapV2Router01.swapExactTokensForTokens( amountIn=123248757273038120000, amountOutMin=1, path=[0x555907a0b5c32DF0fEb35401187aED60a9191D74, 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2], to=0x22F9dCF4647084d6C31b2765F6910cd85C178C18, deadline=1738745579 )
                          • UniswapV2Pair.STATICCALL( )
                          • trumpwifhat.transferFrom( src=0x22F9dCF4647084d6C31b2765F6910cd85C178C18, dst=0xe4bb64b976bA9Fb3647Af2A958760E8C7d7A85aC, rawAmount=123248757273038120000 )
                            transformERC20[TransformERC20Feature (ln:182)]
                            File 1 of 9: ZeroEx
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
                            import "./migrations/LibBootstrap.sol";
                            import "./features/Bootstrap.sol";
                            import "./storage/LibProxyStorage.sol";
                            import "./errors/LibProxyRichErrors.sol";
                            /// @dev An extensible proxy contract that serves as a universal entry point for
                            ///      interacting with the 0x protocol.
                            contract ZeroEx {
                                // solhint-disable separate-by-one-line-in-contract,indent,var-name-mixedcase
                                using LibBytesV06 for bytes;
                                /// @dev Construct this contract and register the `Bootstrap` feature.
                                ///      After constructing this contract, `bootstrap()` should be called
                                ///      to seed the initial feature set.
                                constructor() public {
                                    // Temporarily create and register the bootstrap feature.
                                    // It will deregister itself after `bootstrap()` has been called.
                                    Bootstrap bootstrap = new Bootstrap(msg.sender);
                                    LibProxyStorage.getStorage().impls[bootstrap.bootstrap.selector] =
                                        address(bootstrap);
                                }
                                // solhint-disable state-visibility
                                /// @dev Forwards calls to the appropriate implementation contract.
                                fallback() external payable {
                                    bytes4 selector = msg.data.readBytes4(0);
                                    address impl = getFunctionImplementation(selector);
                                    if (impl == address(0)) {
                                        _revertWithData(LibProxyRichErrors.NotImplementedError(selector));
                                    }
                                    (bool success, bytes memory resultData) = impl.delegatecall(msg.data);
                                    if (!success) {
                                        _revertWithData(resultData);
                                    }
                                    _returnWithData(resultData);
                                }
                                /// @dev Fallback for just receiving ether.
                                receive() external payable {}
                                // solhint-enable state-visibility
                                /// @dev Get the implementation contract of a registered function.
                                /// @param selector The function selector.
                                /// @return impl The implementation contract address.
                                function getFunctionImplementation(bytes4 selector)
                                    public
                                    view
                                    returns (address impl)
                                {
                                    return LibProxyStorage.getStorage().impls[selector];
                                }
                                /// @dev Revert with arbitrary bytes.
                                /// @param data Revert data.
                                function _revertWithData(bytes memory data) private pure {
                                    assembly { revert(add(data, 32), mload(data)) }
                                }
                                /// @dev Return with arbitrary bytes.
                                /// @param data Return data.
                                function _returnWithData(bytes memory data) private pure {
                                    assembly { return(add(data, 32), mload(data)) }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./errors/LibBytesRichErrorsV06.sol";
                            import "./errors/LibRichErrorsV06.sol";
                            library LibBytesV06 {
                                using LibBytesV06 for bytes;
                                /// @dev Gets the memory address for a byte array.
                                /// @param input Byte array to lookup.
                                /// @return memoryAddress Memory address of byte array. This
                                ///         points to the header of the byte array which contains
                                ///         the length.
                                function rawAddress(bytes memory input)
                                    internal
                                    pure
                                    returns (uint256 memoryAddress)
                                {
                                    assembly {
                                        memoryAddress := input
                                    }
                                    return memoryAddress;
                                }
                                /// @dev Gets the memory address for the contents of a byte array.
                                /// @param input Byte array to lookup.
                                /// @return memoryAddress Memory address of the contents of the byte array.
                                function contentAddress(bytes memory input)
                                    internal
                                    pure
                                    returns (uint256 memoryAddress)
                                {
                                    assembly {
                                        memoryAddress := add(input, 32)
                                    }
                                    return memoryAddress;
                                }
                                /// @dev Copies `length` bytes from memory location `source` to `dest`.
                                /// @param dest memory address to copy bytes to.
                                /// @param source memory address to copy bytes from.
                                /// @param length number of bytes to copy.
                                function memCopy(
                                    uint256 dest,
                                    uint256 source,
                                    uint256 length
                                )
                                    internal
                                    pure
                                {
                                    if (length < 32) {
                                        // Handle a partial word by reading destination and masking
                                        // off the bits we are interested in.
                                        // This correctly handles overlap, zero lengths and source == dest
                                        assembly {
                                            let mask := sub(exp(256, sub(32, length)), 1)
                                            let s := and(mload(source), not(mask))
                                            let d := and(mload(dest), mask)
                                            mstore(dest, or(s, d))
                                        }
                                    } else {
                                        // Skip the O(length) loop when source == dest.
                                        if (source == dest) {
                                            return;
                                        }
                                        // For large copies we copy whole words at a time. The final
                                        // word is aligned to the end of the range (instead of after the
                                        // previous) to handle partial words. So a copy will look like this:
                                        //
                                        //  ####
                                        //      ####
                                        //          ####
                                        //            ####
                                        //
                                        // We handle overlap in the source and destination range by
                                        // changing the copying direction. This prevents us from
                                        // overwriting parts of source that we still need to copy.
                                        //
                                        // This correctly handles source == dest
                                        //
                                        if (source > dest) {
                                            assembly {
                                                // We subtract 32 from `sEnd` and `dEnd` because it
                                                // is easier to compare with in the loop, and these
                                                // are also the addresses we need for copying the
                                                // last bytes.
                                                length := sub(length, 32)
                                                let sEnd := add(source, length)
                                                let dEnd := add(dest, length)
                                                // Remember the last 32 bytes of source
                                                // This needs to be done here and not after the loop
                                                // because we may have overwritten the last bytes in
                                                // source already due to overlap.
                                                let last := mload(sEnd)
                                                // Copy whole words front to back
                                                // Note: the first check is always true,
                                                // this could have been a do-while loop.
                                                // solhint-disable-next-line no-empty-blocks
                                                for {} lt(source, sEnd) {} {
                                                    mstore(dest, mload(source))
                                                    source := add(source, 32)
                                                    dest := add(dest, 32)
                                                }
                                                // Write the last 32 bytes
                                                mstore(dEnd, last)
                                            }
                                        } else {
                                            assembly {
                                                // We subtract 32 from `sEnd` and `dEnd` because those
                                                // are the starting points when copying a word at the end.
                                                length := sub(length, 32)
                                                let sEnd := add(source, length)
                                                let dEnd := add(dest, length)
                                                // Remember the first 32 bytes of source
                                                // This needs to be done here and not after the loop
                                                // because we may have overwritten the first bytes in
                                                // source already due to overlap.
                                                let first := mload(source)
                                                // Copy whole words back to front
                                                // We use a signed comparisson here to allow dEnd to become
                                                // negative (happens when source and dest < 32). Valid
                                                // addresses in local memory will never be larger than
                                                // 2**255, so they can be safely re-interpreted as signed.
                                                // Note: the first check is always true,
                                                // this could have been a do-while loop.
                                                // solhint-disable-next-line no-empty-blocks
                                                for {} slt(dest, dEnd) {} {
                                                    mstore(dEnd, mload(sEnd))
                                                    sEnd := sub(sEnd, 32)
                                                    dEnd := sub(dEnd, 32)
                                                }
                                                // Write the first 32 bytes
                                                mstore(dest, first)
                                            }
                                        }
                                    }
                                }
                                /// @dev Returns a slices from a byte array.
                                /// @param b The byte array to take a slice from.
                                /// @param from The starting index for the slice (inclusive).
                                /// @param to The final index for the slice (exclusive).
                                /// @return result The slice containing bytes at indices [from, to)
                                function slice(
                                    bytes memory b,
                                    uint256 from,
                                    uint256 to
                                )
                                    internal
                                    pure
                                    returns (bytes memory result)
                                {
                                    // Ensure that the from and to positions are valid positions for a slice within
                                    // the byte array that is being used.
                                    if (from > to) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.FromLessThanOrEqualsToRequired,
                                            from,
                                            to
                                        ));
                                    }
                                    if (to > b.length) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.ToLessThanOrEqualsLengthRequired,
                                            to,
                                            b.length
                                        ));
                                    }
                                    // Create a new bytes structure and copy contents
                                    result = new bytes(to - from);
                                    memCopy(
                                        result.contentAddress(),
                                        b.contentAddress() + from,
                                        result.length
                                    );
                                    return result;
                                }
                                /// @dev Returns a slice from a byte array without preserving the input.
                                ///      When `from == 0`, the original array will match the slice.
                                ///      In other cases its state will be corrupted.
                                /// @param b The byte array to take a slice from. Will be destroyed in the process.
                                /// @param from The starting index for the slice (inclusive).
                                /// @param to The final index for the slice (exclusive).
                                /// @return result The slice containing bytes at indices [from, to)
                                function sliceDestructive(
                                    bytes memory b,
                                    uint256 from,
                                    uint256 to
                                )
                                    internal
                                    pure
                                    returns (bytes memory result)
                                {
                                    // Ensure that the from and to positions are valid positions for a slice within
                                    // the byte array that is being used.
                                    if (from > to) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.FromLessThanOrEqualsToRequired,
                                            from,
                                            to
                                        ));
                                    }
                                    if (to > b.length) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.ToLessThanOrEqualsLengthRequired,
                                            to,
                                            b.length
                                        ));
                                    }
                                    // Create a new bytes structure around [from, to) in-place.
                                    assembly {
                                        result := add(b, from)
                                        mstore(result, sub(to, from))
                                    }
                                    return result;
                                }
                                /// @dev Pops the last byte off of a byte array by modifying its length.
                                /// @param b Byte array that will be modified.
                                /// @return result The byte that was popped off.
                                function popLastByte(bytes memory b)
                                    internal
                                    pure
                                    returns (bytes1 result)
                                {
                                    if (b.length == 0) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanZeroRequired,
                                            b.length,
                                            0
                                        ));
                                    }
                                    // Store last byte.
                                    result = b[b.length - 1];
                                    assembly {
                                        // Decrement length of byte array.
                                        let newLen := sub(mload(b), 1)
                                        mstore(b, newLen)
                                    }
                                    return result;
                                }
                                /// @dev Tests equality of two byte arrays.
                                /// @param lhs First byte array to compare.
                                /// @param rhs Second byte array to compare.
                                /// @return equal True if arrays are the same. False otherwise.
                                function equals(
                                    bytes memory lhs,
                                    bytes memory rhs
                                )
                                    internal
                                    pure
                                    returns (bool equal)
                                {
                                    // Keccak gas cost is 30 + numWords * 6. This is a cheap way to compare.
                                    // We early exit on unequal lengths, but keccak would also correctly
                                    // handle this.
                                    return lhs.length == rhs.length && keccak256(lhs) == keccak256(rhs);
                                }
                                /// @dev Reads an address from a position in a byte array.
                                /// @param b Byte array containing an address.
                                /// @param index Index in byte array of address.
                                /// @return result address from byte array.
                                function readAddress(
                                    bytes memory b,
                                    uint256 index
                                )
                                    internal
                                    pure
                                    returns (address result)
                                {
                                    if (b.length < index + 20) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsTwentyRequired,
                                            b.length,
                                            index + 20 // 20 is length of address
                                        ));
                                    }
                                    // Add offset to index:
                                    // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
                                    // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
                                    index += 20;
                                    // Read address from array memory
                                    assembly {
                                        // 1. Add index to address of bytes array
                                        // 2. Load 32-byte word from memory
                                        // 3. Apply 20-byte mask to obtain address
                                        result := and(mload(add(b, index)), 0xffffffffffffffffffffffffffffffffffffffff)
                                    }
                                    return result;
                                }
                                /// @dev Writes an address into a specific position in a byte array.
                                /// @param b Byte array to insert address into.
                                /// @param index Index in byte array of address.
                                /// @param input Address to put into byte array.
                                function writeAddress(
                                    bytes memory b,
                                    uint256 index,
                                    address input
                                )
                                    internal
                                    pure
                                {
                                    if (b.length < index + 20) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsTwentyRequired,
                                            b.length,
                                            index + 20 // 20 is length of address
                                        ));
                                    }
                                    // Add offset to index:
                                    // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
                                    // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
                                    index += 20;
                                    // Store address into array memory
                                    assembly {
                                        // The address occupies 20 bytes and mstore stores 32 bytes.
                                        // First fetch the 32-byte word where we'll be storing the address, then
                                        // apply a mask so we have only the bytes in the word that the address will not occupy.
                                        // Then combine these bytes with the address and store the 32 bytes back to memory with mstore.
                                        // 1. Add index to address of bytes array
                                        // 2. Load 32-byte word from memory
                                        // 3. Apply 12-byte mask to obtain extra bytes occupying word of memory where we'll store the address
                                        let neighbors := and(
                                            mload(add(b, index)),
                                            0xffffffffffffffffffffffff0000000000000000000000000000000000000000
                                        )
                                        // Make sure input address is clean.
                                        // (Solidity does not guarantee this)
                                        input := and(input, 0xffffffffffffffffffffffffffffffffffffffff)
                                        // Store the neighbors and address into memory
                                        mstore(add(b, index), xor(input, neighbors))
                                    }
                                }
                                /// @dev Reads a bytes32 value from a position in a byte array.
                                /// @param b Byte array containing a bytes32 value.
                                /// @param index Index in byte array of bytes32 value.
                                /// @return result bytes32 value from byte array.
                                function readBytes32(
                                    bytes memory b,
                                    uint256 index
                                )
                                    internal
                                    pure
                                    returns (bytes32 result)
                                {
                                    if (b.length < index + 32) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsThirtyTwoRequired,
                                            b.length,
                                            index + 32
                                        ));
                                    }
                                    // Arrays are prefixed by a 256 bit length parameter
                                    index += 32;
                                    // Read the bytes32 from array memory
                                    assembly {
                                        result := mload(add(b, index))
                                    }
                                    return result;
                                }
                                /// @dev Writes a bytes32 into a specific position in a byte array.
                                /// @param b Byte array to insert <input> into.
                                /// @param index Index in byte array of <input>.
                                /// @param input bytes32 to put into byte array.
                                function writeBytes32(
                                    bytes memory b,
                                    uint256 index,
                                    bytes32 input
                                )
                                    internal
                                    pure
                                {
                                    if (b.length < index + 32) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsThirtyTwoRequired,
                                            b.length,
                                            index + 32
                                        ));
                                    }
                                    // Arrays are prefixed by a 256 bit length parameter
                                    index += 32;
                                    // Read the bytes32 from array memory
                                    assembly {
                                        mstore(add(b, index), input)
                                    }
                                }
                                /// @dev Reads a uint256 value from a position in a byte array.
                                /// @param b Byte array containing a uint256 value.
                                /// @param index Index in byte array of uint256 value.
                                /// @return result uint256 value from byte array.
                                function readUint256(
                                    bytes memory b,
                                    uint256 index
                                )
                                    internal
                                    pure
                                    returns (uint256 result)
                                {
                                    result = uint256(readBytes32(b, index));
                                    return result;
                                }
                                /// @dev Writes a uint256 into a specific position in a byte array.
                                /// @param b Byte array to insert <input> into.
                                /// @param index Index in byte array of <input>.
                                /// @param input uint256 to put into byte array.
                                function writeUint256(
                                    bytes memory b,
                                    uint256 index,
                                    uint256 input
                                )
                                    internal
                                    pure
                                {
                                    writeBytes32(b, index, bytes32(input));
                                }
                                /// @dev Reads an unpadded bytes4 value from a position in a byte array.
                                /// @param b Byte array containing a bytes4 value.
                                /// @param index Index in byte array of bytes4 value.
                                /// @return result bytes4 value from byte array.
                                function readBytes4(
                                    bytes memory b,
                                    uint256 index
                                )
                                    internal
                                    pure
                                    returns (bytes4 result)
                                {
                                    if (b.length < index + 4) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsFourRequired,
                                            b.length,
                                            index + 4
                                        ));
                                    }
                                    // Arrays are prefixed by a 32 byte length field
                                    index += 32;
                                    // Read the bytes4 from array memory
                                    assembly {
                                        result := mload(add(b, index))
                                        // Solidity does not require us to clean the trailing bytes.
                                        // We do it anyway
                                        result := and(result, 0xFFFFFFFF00000000000000000000000000000000000000000000000000000000)
                                    }
                                    return result;
                                }
                                /// @dev Writes a new length to a byte array.
                                ///      Decreasing length will lead to removing the corresponding lower order bytes from the byte array.
                                ///      Increasing length may lead to appending adjacent in-memory bytes to the end of the byte array.
                                /// @param b Bytes array to write new length to.
                                /// @param length New length of byte array.
                                function writeLength(bytes memory b, uint256 length)
                                    internal
                                    pure
                                {
                                    assembly {
                                        mstore(b, length)
                                    }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibBytesRichErrorsV06 {
                                enum InvalidByteOperationErrorCodes {
                                    FromLessThanOrEqualsToRequired,
                                    ToLessThanOrEqualsLengthRequired,
                                    LengthGreaterThanZeroRequired,
                                    LengthGreaterThanOrEqualsFourRequired,
                                    LengthGreaterThanOrEqualsTwentyRequired,
                                    LengthGreaterThanOrEqualsThirtyTwoRequired,
                                    LengthGreaterThanOrEqualsNestedBytesLengthRequired,
                                    DestinationLengthGreaterThanOrEqualSourceLengthRequired
                                }
                                // bytes4(keccak256("InvalidByteOperationError(uint8,uint256,uint256)"))
                                bytes4 internal constant INVALID_BYTE_OPERATION_ERROR_SELECTOR =
                                    0x28006595;
                                // solhint-disable func-name-mixedcase
                                function InvalidByteOperationError(
                                    InvalidByteOperationErrorCodes errorCode,
                                    uint256 offset,
                                    uint256 required
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        INVALID_BYTE_OPERATION_ERROR_SELECTOR,
                                        errorCode,
                                        offset,
                                        required
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibRichErrorsV06 {
                                // bytes4(keccak256("Error(string)"))
                                bytes4 internal constant STANDARD_ERROR_SELECTOR = 0x08c379a0;
                                // solhint-disable func-name-mixedcase
                                /// @dev ABI encode a standard, string revert error payload.
                                ///      This is the same payload that would be included by a `revert(string)`
                                ///      solidity statement. It has the function signature `Error(string)`.
                                /// @param message The error string.
                                /// @return The ABI encoded error.
                                function StandardError(string memory message)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        STANDARD_ERROR_SELECTOR,
                                        bytes(message)
                                    );
                                }
                                // solhint-enable func-name-mixedcase
                                /// @dev Reverts an encoded rich revert reason `errorData`.
                                /// @param errorData ABI encoded error data.
                                function rrevert(bytes memory errorData)
                                    internal
                                    pure
                                {
                                    assembly {
                                        revert(add(errorData, 0x20), mload(errorData))
                                    }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "../errors/LibProxyRichErrors.sol";
                            library LibBootstrap {
                                /// @dev Magic bytes returned by the bootstrapper to indicate success.
                                ///      This is `keccack('BOOTSTRAP_SUCCESS')`.
                                bytes4 internal constant BOOTSTRAP_SUCCESS = 0xd150751b;
                                using LibRichErrorsV06 for bytes;
                                /// @dev Perform a delegatecall and ensure it returns the magic bytes.
                                /// @param target The call target.
                                /// @param data The call data.
                                function delegatecallBootstrapFunction(
                                    address target,
                                    bytes memory data
                                )
                                    internal
                                {
                                    (bool success, bytes memory resultData) = target.delegatecall(data);
                                    if (!success ||
                                        resultData.length != 32 ||
                                        abi.decode(resultData, (bytes4)) != BOOTSTRAP_SUCCESS)
                                    {
                                        LibProxyRichErrors.BootstrapCallFailedError(target, resultData).rrevert();
                                    }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibProxyRichErrors {
                                // solhint-disable func-name-mixedcase
                                function NotImplementedError(bytes4 selector)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("NotImplementedError(bytes4)")),
                                        selector
                                    );
                                }
                                function InvalidBootstrapCallerError(address actual, address expected)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InvalidBootstrapCallerError(address,address)")),
                                        actual,
                                        expected
                                    );
                                }
                                function InvalidDieCallerError(address actual, address expected)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InvalidDieCallerError(address,address)")),
                                        actual,
                                        expected
                                    );
                                }
                                function BootstrapCallFailedError(address target, bytes memory resultData)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("BootstrapCallFailedError(address,bytes)")),
                                        target,
                                        resultData
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "../migrations/LibBootstrap.sol";
                            import "../storage/LibProxyStorage.sol";
                            import "./IBootstrap.sol";
                            /// @dev Detachable `bootstrap()` feature.
                            contract Bootstrap is
                                IBootstrap
                            {
                                // solhint-disable state-visibility,indent
                                /// @dev The ZeroEx contract.
                                ///      This has to be immutable to persist across delegatecalls.
                                address immutable private _deployer;
                                /// @dev The implementation address of this contract.
                                ///      This has to be immutable to persist across delegatecalls.
                                address immutable private _implementation;
                                /// @dev The deployer.
                                ///      This has to be immutable to persist across delegatecalls.
                                address immutable private _bootstrapCaller;
                                // solhint-enable state-visibility,indent
                                using LibRichErrorsV06 for bytes;
                                /// @dev Construct this contract and set the bootstrap migration contract.
                                ///      After constructing this contract, `bootstrap()` should be called
                                ///      to seed the initial feature set.
                                /// @param bootstrapCaller The allowed caller of `bootstrap()`.
                                constructor(address bootstrapCaller) public {
                                    _deployer = msg.sender;
                                    _implementation = address(this);
                                    _bootstrapCaller = bootstrapCaller;
                                }
                                /// @dev Bootstrap the initial feature set of this contract by delegatecalling
                                ///      into `target`. Before exiting the `bootstrap()` function will
                                ///      deregister itself from the proxy to prevent being called again.
                                /// @param target The bootstrapper contract address.
                                /// @param callData The call data to execute on `target`.
                                function bootstrap(address target, bytes calldata callData) external override {
                                    // Only the bootstrap caller can call this function.
                                    if (msg.sender != _bootstrapCaller) {
                                        LibProxyRichErrors.InvalidBootstrapCallerError(
                                            msg.sender,
                                            _bootstrapCaller
                                        ).rrevert();
                                    }
                                    // Deregister.
                                    LibProxyStorage.getStorage().impls[this.bootstrap.selector] = address(0);
                                    // Self-destruct.
                                    Bootstrap(_implementation).die();
                                    // Call the bootstrapper.
                                    LibBootstrap.delegatecallBootstrapFunction(target, callData);
                                }
                                /// @dev Self-destructs this contract.
                                ///      Can only be called by the deployer.
                                function die() external {
                                    if (msg.sender != _deployer) {
                                        LibProxyRichErrors.InvalidDieCallerError(msg.sender, _deployer).rrevert();
                                    }
                                    selfdestruct(msg.sender);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "./LibStorage.sol";
                            /// @dev Storage helpers for the proxy contract.
                            library LibProxyStorage {
                                /// @dev Storage bucket for proxy contract.
                                struct Storage {
                                    // Mapping of function selector -> function implementation
                                    mapping(bytes4 => address) impls;
                                    // The owner of the proxy contract.
                                    address owner;
                                }
                                /// @dev Get the storage bucket for this contract.
                                function getStorage() internal pure returns (Storage storage stor) {
                                    uint256 storageSlot = LibStorage.getStorageSlot(
                                        LibStorage.StorageId.Proxy
                                    );
                                    // Dip into assembly to change the slot pointed to by the local
                                    // variable `stor`.
                                    // See https://solidity.readthedocs.io/en/v0.6.8/assembly.html?highlight=slot#access-to-external-variables-functions-and-libraries
                                    assembly { stor_slot := storageSlot }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            /// @dev Common storage helpers
                            library LibStorage {
                                /// @dev What to bit-shift a storage ID by to get its slot.
                                ///      This gives us a maximum of 2**128 inline fields in each bucket.
                                uint256 private constant STORAGE_SLOT_EXP = 128;
                                /// @dev Storage IDs for feature storage buckets.
                                ///      WARNING: APPEND-ONLY.
                                enum StorageId {
                                    Proxy,
                                    SimpleFunctionRegistry,
                                    Ownable,
                                    TokenSpender,
                                    TransformERC20
                                }
                                /// @dev Get the storage slot given a storage ID. We assign unique, well-spaced
                                ///     slots to storage bucket variables to ensure they do not overlap.
                                ///     See: https://solidity.readthedocs.io/en/v0.6.6/assembly.html#access-to-external-variables-functions-and-libraries
                                /// @param storageId An entry in `StorageId`
                                /// @return slot The storage slot.
                                function getStorageSlot(StorageId storageId)
                                    internal
                                    pure
                                    returns (uint256 slot)
                                {
                                    // This should never overflow with a reasonable `STORAGE_SLOT_EXP`
                                    // because Solidity will do a range check on `storageId` during the cast.
                                    return (uint256(storageId) + 1) << STORAGE_SLOT_EXP;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            /// @dev Detachable `bootstrap()` feature.
                            interface IBootstrap {
                                /// @dev Bootstrap the initial feature set of this contract by delegatecalling
                                ///      into `target`. Before exiting the `bootstrap()` function will
                                ///      deregister itself from the proxy to prevent being called again.
                                /// @param target The bootstrapper contract address.
                                /// @param callData The call data to execute on `target`.
                                function bootstrap(address target, bytes calldata callData) external;
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibCommonRichErrors {
                                // solhint-disable func-name-mixedcase
                                function OnlyCallableBySelfError(address sender)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("OnlyCallableBySelfError(address)")),
                                        sender
                                    );
                                }
                                function IllegalReentrancyError()
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("IllegalReentrancyError()"))
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibOwnableRichErrors {
                                // solhint-disable func-name-mixedcase
                                function OnlyOwnerError(
                                    address sender,
                                    address owner
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("OnlyOwnerError(address,address)")),
                                        sender,
                                        owner
                                    );
                                }
                                function TransferOwnerToZeroError()
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("TransferOwnerToZeroError()"))
                                    );
                                }
                                function MigrateCallFailedError(address target, bytes memory resultData)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("MigrateCallFailedError(address,bytes)")),
                                        target,
                                        resultData
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibSimpleFunctionRegistryRichErrors {
                                // solhint-disable func-name-mixedcase
                                function NotInRollbackHistoryError(bytes4 selector, address targetImpl)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("NotInRollbackHistoryError(bytes4,address)")),
                                        selector,
                                        targetImpl
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibSpenderRichErrors {
                                // solhint-disable func-name-mixedcase
                                function SpenderERC20TransferFromFailedError(
                                    address token,
                                    address owner,
                                    address to,
                                    uint256 amount,
                                    bytes memory errorData
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("SpenderERC20TransferFromFailedError(address,address,address,uint256,bytes)")),
                                        token,
                                        owner,
                                        to,
                                        amount,
                                        errorData
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibTransformERC20RichErrors {
                                // solhint-disable func-name-mixedcase,separate-by-one-line-in-contract
                                function InsufficientEthAttachedError(
                                    uint256 ethAttached,
                                    uint256 ethNeeded
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InsufficientEthAttachedError(uint256,uint256)")),
                                        ethAttached,
                                        ethNeeded
                                    );
                                }
                                function IncompleteTransformERC20Error(
                                    address outputToken,
                                    uint256 outputTokenAmount,
                                    uint256 minOutputTokenAmount
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("IncompleteTransformERC20Error(address,uint256,uint256)")),
                                        outputToken,
                                        outputTokenAmount,
                                        minOutputTokenAmount
                                    );
                                }
                                function NegativeTransformERC20OutputError(
                                    address outputToken,
                                    uint256 outputTokenLostAmount
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("NegativeTransformERC20OutputError(address,uint256)")),
                                        outputToken,
                                        outputTokenLostAmount
                                    );
                                }
                                function TransformerFailedError(
                                    address transformer,
                                    bytes memory transformerData,
                                    bytes memory resultData
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("TransformerFailedError(address,bytes,bytes)")),
                                        transformer,
                                        transformerData,
                                        resultData
                                    );
                                }
                                // Common Transformer errors ///////////////////////////////////////////////
                                function OnlyCallableByDeployerError(
                                    address caller,
                                    address deployer
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("OnlyCallableByDeployerError(address,address)")),
                                        caller,
                                        deployer
                                    );
                                }
                                function InvalidExecutionContextError(
                                    address actualContext,
                                    address expectedContext
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InvalidExecutionContextError(address,address)")),
                                        actualContext,
                                        expectedContext
                                    );
                                }
                                enum InvalidTransformDataErrorCode {
                                    INVALID_TOKENS,
                                    INVALID_ARRAY_LENGTH
                                }
                                function InvalidTransformDataError(
                                    InvalidTransformDataErrorCode errorCode,
                                    bytes memory transformData
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InvalidTransformDataError(uint8,bytes)")),
                                        errorCode,
                                        transformData
                                    );
                                }
                                // FillQuoteTransformer errors /////////////////////////////////////////////
                                function IncompleteFillSellQuoteError(
                                    address sellToken,
                                    uint256 soldAmount,
                                    uint256 sellAmount
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("IncompleteFillSellQuoteError(address,uint256,uint256)")),
                                        sellToken,
                                        soldAmount,
                                        sellAmount
                                    );
                                }
                                function IncompleteFillBuyQuoteError(
                                    address buyToken,
                                    uint256 boughtAmount,
                                    uint256 buyAmount
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("IncompleteFillBuyQuoteError(address,uint256,uint256)")),
                                        buyToken,
                                        boughtAmount,
                                        buyAmount
                                    );
                                }
                                function InsufficientTakerTokenError(
                                    uint256 tokenBalance,
                                    uint256 tokensNeeded
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InsufficientTakerTokenError(uint256,uint256)")),
                                        tokenBalance,
                                        tokensNeeded
                                    );
                                }
                                function InsufficientProtocolFeeError(
                                    uint256 ethBalance,
                                    uint256 ethNeeded
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InsufficientProtocolFeeError(uint256,uint256)")),
                                        ethBalance,
                                        ethNeeded
                                    );
                                }
                                function InvalidERC20AssetDataError(
                                    bytes memory assetData
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InvalidERC20AssetDataError(bytes)")),
                                        assetData
                                    );
                                }
                                function InvalidTakerFeeTokenError(
                                    address token
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InvalidTakerFeeTokenError(address)")),
                                        token
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibWalletRichErrors {
                                // solhint-disable func-name-mixedcase
                                function WalletExecuteCallFailedError(
                                    address wallet,
                                    address callTarget,
                                    bytes memory callData,
                                    uint256 callValue,
                                    bytes memory errorData
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("WalletExecuteCallFailedError(address,address,bytes,uint256,bytes)")),
                                        wallet,
                                        callTarget,
                                        callData,
                                        callValue,
                                        errorData
                                    );
                                }
                                function WalletExecuteDelegateCallFailedError(
                                    address wallet,
                                    address callTarget,
                                    bytes memory callData,
                                    bytes memory errorData
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("WalletExecuteDelegateCallFailedError(address,address,bytes,bytes)")),
                                        wallet,
                                        callTarget,
                                        callData,
                                        errorData
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/AuthorizableV06.sol";
                            import "../errors/LibSpenderRichErrors.sol";
                            import "./IAllowanceTarget.sol";
                            /// @dev The allowance target for the TokenSpender feature.
                            contract AllowanceTarget is
                                IAllowanceTarget,
                                AuthorizableV06
                            {
                                // solhint-disable no-unused-vars,indent,no-empty-blocks
                                using LibRichErrorsV06 for bytes;
                                /// @dev Execute an arbitrary call. Only an authority can call this.
                                /// @param target The call target.
                                /// @param callData The call data.
                                /// @return resultData The data returned by the call.
                                function executeCall(
                                    address payable target,
                                    bytes calldata callData
                                )
                                    external
                                    override
                                    onlyAuthorized
                                    returns (bytes memory resultData)
                                {
                                    bool success;
                                    (success, resultData) = target.call(callData);
                                    if (!success) {
                                        resultData.rrevert();
                                    }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./interfaces/IAuthorizableV06.sol";
                            import "./errors/LibRichErrorsV06.sol";
                            import "./errors/LibAuthorizableRichErrorsV06.sol";
                            import "./OwnableV06.sol";
                            // solhint-disable no-empty-blocks
                            contract AuthorizableV06 is
                                OwnableV06,
                                IAuthorizableV06
                            {
                                /// @dev Only authorized addresses can invoke functions with this modifier.
                                modifier onlyAuthorized {
                                    _assertSenderIsAuthorized();
                                    _;
                                }
                                // @dev Whether an address is authorized to call privileged functions.
                                // @param 0 Address to query.
                                // @return 0 Whether the address is authorized.
                                mapping (address => bool) public override authorized;
                                // @dev Whether an address is authorized to call privileged functions.
                                // @param 0 Index of authorized address.
                                // @return 0 Authorized address.
                                address[] public override authorities;
                                /// @dev Initializes the `owner` address.
                                constructor()
                                    public
                                    OwnableV06()
                                {}
                                /// @dev Authorizes an address.
                                /// @param target Address to authorize.
                                function addAuthorizedAddress(address target)
                                    external
                                    override
                                    onlyOwner
                                {
                                    _addAuthorizedAddress(target);
                                }
                                /// @dev Removes authorizion of an address.
                                /// @param target Address to remove authorization from.
                                function removeAuthorizedAddress(address target)
                                    external
                                    override
                                    onlyOwner
                                {
                                    if (!authorized[target]) {
                                        LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.TargetNotAuthorizedError(target));
                                    }
                                    for (uint256 i = 0; i < authorities.length; i++) {
                                        if (authorities[i] == target) {
                                            _removeAuthorizedAddressAtIndex(target, i);
                                            break;
                                        }
                                    }
                                }
                                /// @dev Removes authorizion of an address.
                                /// @param target Address to remove authorization from.
                                /// @param index Index of target in authorities array.
                                function removeAuthorizedAddressAtIndex(
                                    address target,
                                    uint256 index
                                )
                                    external
                                    override
                                    onlyOwner
                                {
                                    _removeAuthorizedAddressAtIndex(target, index);
                                }
                                /// @dev Gets all authorized addresses.
                                /// @return Array of authorized addresses.
                                function getAuthorizedAddresses()
                                    external
                                    override
                                    view
                                    returns (address[] memory)
                                {
                                    return authorities;
                                }
                                /// @dev Reverts if msg.sender is not authorized.
                                function _assertSenderIsAuthorized()
                                    internal
                                    view
                                {
                                    if (!authorized[msg.sender]) {
                                        LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.SenderNotAuthorizedError(msg.sender));
                                    }
                                }
                                /// @dev Authorizes an address.
                                /// @param target Address to authorize.
                                function _addAuthorizedAddress(address target)
                                    internal
                                {
                                    // Ensure that the target is not the zero address.
                                    if (target == address(0)) {
                                        LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.ZeroCantBeAuthorizedError());
                                    }
                                    // Ensure that the target is not already authorized.
                                    if (authorized[target]) {
                                        LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.TargetAlreadyAuthorizedError(target));
                                    }
                                    authorized[target] = true;
                                    authorities.push(target);
                                    emit AuthorizedAddressAdded(target, msg.sender);
                                }
                                /// @dev Removes authorizion of an address.
                                /// @param target Address to remove authorization from.
                                /// @param index Index of target in authorities array.
                                function _removeAuthorizedAddressAtIndex(
                                    address target,
                                    uint256 index
                                )
                                    internal
                                {
                                    if (!authorized[target]) {
                                        LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.TargetNotAuthorizedError(target));
                                    }
                                    if (index >= authorities.length) {
                                        LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.IndexOutOfBoundsError(
                                            index,
                                            authorities.length
                                        ));
                                    }
                                    if (authorities[index] != target) {
                                        LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.AuthorizedAddressMismatchError(
                                            authorities[index],
                                            target
                                        ));
                                    }
                                    delete authorized[target];
                                    authorities[index] = authorities[authorities.length - 1];
                                    authorities.pop();
                                    emit AuthorizedAddressRemoved(target, msg.sender);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./IOwnableV06.sol";
                            interface IAuthorizableV06 is
                                IOwnableV06
                            {
                                // Event logged when a new address is authorized.
                                event AuthorizedAddressAdded(
                                    address indexed target,
                                    address indexed caller
                                );
                                // Event logged when a currently authorized address is unauthorized.
                                event AuthorizedAddressRemoved(
                                    address indexed target,
                                    address indexed caller
                                );
                                /// @dev Authorizes an address.
                                /// @param target Address to authorize.
                                function addAuthorizedAddress(address target)
                                    external;
                                /// @dev Removes authorizion of an address.
                                /// @param target Address to remove authorization from.
                                function removeAuthorizedAddress(address target)
                                    external;
                                /// @dev Removes authorizion of an address.
                                /// @param target Address to remove authorization from.
                                /// @param index Index of target in authorities array.
                                function removeAuthorizedAddressAtIndex(
                                    address target,
                                    uint256 index
                                )
                                    external;
                                /// @dev Gets all authorized addresses.
                                /// @return authorizedAddresses Array of authorized addresses.
                                function getAuthorizedAddresses()
                                    external
                                    view
                                    returns (address[] memory authorizedAddresses);
                                /// @dev Whether an adderss is authorized to call privileged functions.
                                /// @param addr Address to query.
                                /// @return isAuthorized Whether the address is authorized.
                                function authorized(address addr) external view returns (bool isAuthorized);
                                /// @dev All addresseses authorized to call privileged functions.
                                /// @param idx Index of authorized address.
                                /// @return addr Authorized address.
                                function authorities(uint256 idx) external view returns (address addr);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            interface IOwnableV06 {
                                /// @dev Emitted by Ownable when ownership is transferred.
                                /// @param previousOwner The previous owner of the contract.
                                /// @param newOwner The new owner of the contract.
                                event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
                                /// @dev Transfers ownership of the contract to a new address.
                                /// @param newOwner The address that will become the owner.
                                function transferOwnership(address newOwner) external;
                                /// @dev The owner of this contract.
                                /// @return ownerAddress The owner address.
                                function owner() external view returns (address ownerAddress);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibAuthorizableRichErrorsV06 {
                                // bytes4(keccak256("AuthorizedAddressMismatchError(address,address)"))
                                bytes4 internal constant AUTHORIZED_ADDRESS_MISMATCH_ERROR_SELECTOR =
                                    0x140a84db;
                                // bytes4(keccak256("IndexOutOfBoundsError(uint256,uint256)"))
                                bytes4 internal constant INDEX_OUT_OF_BOUNDS_ERROR_SELECTOR =
                                    0xe9f83771;
                                // bytes4(keccak256("SenderNotAuthorizedError(address)"))
                                bytes4 internal constant SENDER_NOT_AUTHORIZED_ERROR_SELECTOR =
                                    0xb65a25b9;
                                // bytes4(keccak256("TargetAlreadyAuthorizedError(address)"))
                                bytes4 internal constant TARGET_ALREADY_AUTHORIZED_ERROR_SELECTOR =
                                    0xde16f1a0;
                                // bytes4(keccak256("TargetNotAuthorizedError(address)"))
                                bytes4 internal constant TARGET_NOT_AUTHORIZED_ERROR_SELECTOR =
                                    0xeb5108a2;
                                // bytes4(keccak256("ZeroCantBeAuthorizedError()"))
                                bytes internal constant ZERO_CANT_BE_AUTHORIZED_ERROR_BYTES =
                                    hex"57654fe4";
                                // solhint-disable func-name-mixedcase
                                function AuthorizedAddressMismatchError(
                                    address authorized,
                                    address target
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        AUTHORIZED_ADDRESS_MISMATCH_ERROR_SELECTOR,
                                        authorized,
                                        target
                                    );
                                }
                                function IndexOutOfBoundsError(
                                    uint256 index,
                                    uint256 length
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        INDEX_OUT_OF_BOUNDS_ERROR_SELECTOR,
                                        index,
                                        length
                                    );
                                }
                                function SenderNotAuthorizedError(address sender)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        SENDER_NOT_AUTHORIZED_ERROR_SELECTOR,
                                        sender
                                    );
                                }
                                function TargetAlreadyAuthorizedError(address target)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        TARGET_ALREADY_AUTHORIZED_ERROR_SELECTOR,
                                        target
                                    );
                                }
                                function TargetNotAuthorizedError(address target)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        TARGET_NOT_AUTHORIZED_ERROR_SELECTOR,
                                        target
                                    );
                                }
                                function ZeroCantBeAuthorizedError()
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return ZERO_CANT_BE_AUTHORIZED_ERROR_BYTES;
                                }
                            }
                            /*
                              Copyright 2019 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./interfaces/IOwnableV06.sol";
                            import "./errors/LibRichErrorsV06.sol";
                            import "./errors/LibOwnableRichErrorsV06.sol";
                            contract OwnableV06 is
                                IOwnableV06
                            {
                                /// @dev The owner of this contract.
                                /// @return 0 The owner address.
                                address public override owner;
                                constructor() public {
                                    owner = msg.sender;
                                }
                                modifier onlyOwner() {
                                    _assertSenderIsOwner();
                                    _;
                                }
                                /// @dev Change the owner of this contract.
                                /// @param newOwner New owner address.
                                function transferOwnership(address newOwner)
                                    public
                                    override
                                    onlyOwner
                                {
                                    if (newOwner == address(0)) {
                                        LibRichErrorsV06.rrevert(LibOwnableRichErrorsV06.TransferOwnerToZeroError());
                                    } else {
                                        owner = newOwner;
                                        emit OwnershipTransferred(msg.sender, newOwner);
                                    }
                                }
                                function _assertSenderIsOwner()
                                    internal
                                    view
                                {
                                    if (msg.sender != owner) {
                                        LibRichErrorsV06.rrevert(LibOwnableRichErrorsV06.OnlyOwnerError(
                                            msg.sender,
                                            owner
                                        ));
                                    }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibOwnableRichErrorsV06 {
                                // bytes4(keccak256("OnlyOwnerError(address,address)"))
                                bytes4 internal constant ONLY_OWNER_ERROR_SELECTOR =
                                    0x1de45ad1;
                                // bytes4(keccak256("TransferOwnerToZeroError()"))
                                bytes internal constant TRANSFER_OWNER_TO_ZERO_ERROR_BYTES =
                                    hex"e69edc3e";
                                // solhint-disable func-name-mixedcase
                                function OnlyOwnerError(
                                    address sender,
                                    address owner
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        ONLY_OWNER_ERROR_SELECTOR,
                                        sender,
                                        owner
                                    );
                                }
                                function TransferOwnerToZeroError()
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return TRANSFER_OWNER_TO_ZERO_ERROR_BYTES;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/interfaces/IAuthorizableV06.sol";
                            /// @dev The allowance target for the TokenSpender feature.
                            interface IAllowanceTarget is
                                IAuthorizableV06
                            {
                                /// @dev Execute an arbitrary call. Only an authority can call this.
                                /// @param target The call target.
                                /// @param callData The call data.
                                /// @return resultData The data returned by the call.
                                function executeCall(
                                    address payable target,
                                    bytes calldata callData
                                )
                                    external
                                    returns (bytes memory resultData);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibOwnableRichErrorsV06.sol";
                            import "../errors/LibWalletRichErrors.sol";
                            import "./IFlashWallet.sol";
                            /// @dev A contract that can execute arbitrary calls from its owner.
                            contract FlashWallet is
                                IFlashWallet
                            {
                                // solhint-disable no-unused-vars,indent,no-empty-blocks
                                using LibRichErrorsV06 for bytes;
                                // solhint-disable
                                /// @dev Store the owner/deployer as an immutable to make this contract stateless.
                                address public override immutable owner;
                                // solhint-enable
                                constructor() public {
                                    // The deployer is the owner.
                                    owner = msg.sender;
                                }
                                /// @dev Allows only the (immutable) owner to call a function.
                                modifier onlyOwner() virtual {
                                    if (msg.sender != owner) {
                                        LibOwnableRichErrorsV06.OnlyOwnerError(
                                            msg.sender,
                                            owner
                                        ).rrevert();
                                    }
                                    _;
                                }
                                /// @dev Execute an arbitrary call. Only an authority can call this.
                                /// @param target The call target.
                                /// @param callData The call data.
                                /// @param value Ether to attach to the call.
                                /// @return resultData The data returned by the call.
                                function executeCall(
                                    address payable target,
                                    bytes calldata callData,
                                    uint256 value
                                )
                                    external
                                    payable
                                    override
                                    onlyOwner
                                    returns (bytes memory resultData)
                                {
                                    bool success;
                                    (success, resultData) = target.call{value: value}(callData);
                                    if (!success) {
                                        LibWalletRichErrors
                                            .WalletExecuteCallFailedError(
                                                address(this),
                                                target,
                                                callData,
                                                value,
                                                resultData
                                            )
                                            .rrevert();
                                    }
                                }
                                /// @dev Execute an arbitrary delegatecall, in the context of this puppet.
                                ///      Only an authority can call this.
                                /// @param target The call target.
                                /// @param callData The call data.
                                /// @return resultData The data returned by the call.
                                function executeDelegateCall(
                                    address payable target,
                                    bytes calldata callData
                                )
                                    external
                                    payable
                                    override
                                    onlyOwner
                                    returns (bytes memory resultData)
                                {
                                    bool success;
                                    (success, resultData) = target.delegatecall(callData);
                                    if (!success) {
                                        LibWalletRichErrors
                                            .WalletExecuteDelegateCallFailedError(
                                                address(this),
                                                target,
                                                callData,
                                                resultData
                                            )
                                            .rrevert();
                                    }
                                }
                                // solhint-disable
                                /// @dev Allows this contract to receive ether.
                                receive() external override payable {}
                                // solhint-enable
                                /// @dev Signal support for receiving ERC1155 tokens.
                                /// @param interfaceID The interface ID, as per ERC-165 rules.
                                /// @return hasSupport `true` if this contract supports an ERC-165 interface.
                                function supportsInterface(bytes4 interfaceID)
                                    external
                                    pure
                                    returns (bool hasSupport)
                                {
                                    return  interfaceID == this.supportsInterface.selector ||
                                            interfaceID == this.onERC1155Received.selector ^ this.onERC1155BatchReceived.selector ||
                                            interfaceID == this.tokenFallback.selector;
                                }
                                ///  @dev Allow this contract to receive ERC1155 tokens.
                                ///  @return success  `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))`
                                function onERC1155Received(
                                    address, // operator,
                                    address, // from,
                                    uint256, // id,
                                    uint256, // value,
                                    bytes calldata //data
                                )
                                    external
                                    pure
                                    returns (bytes4 success)
                                {
                                    return this.onERC1155Received.selector;
                                }
                                ///  @dev Allow this contract to receive ERC1155 tokens.
                                ///  @return success  `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))`
                                function onERC1155BatchReceived(
                                    address, // operator,
                                    address, // from,
                                    uint256[] calldata, // ids,
                                    uint256[] calldata, // values,
                                    bytes calldata // data
                                )
                                    external
                                    pure
                                    returns (bytes4 success)
                                {
                                    return this.onERC1155BatchReceived.selector;
                                }
                                /// @dev Allows this contract to receive ERC223 tokens.
                                function tokenFallback(
                                    address, // from,
                                    uint256, // value,
                                    bytes calldata // value
                                )
                                    external
                                    pure
                                {}
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/interfaces/IOwnableV06.sol";
                            /// @dev A contract that can execute arbitrary calls from its owner.
                            interface IFlashWallet {
                                /// @dev Execute an arbitrary call. Only an authority can call this.
                                /// @param target The call target.
                                /// @param callData The call data.
                                /// @param value Ether to attach to the call.
                                /// @return resultData The data returned by the call.
                                function executeCall(
                                    address payable target,
                                    bytes calldata callData,
                                    uint256 value
                                )
                                    external
                                    payable
                                    returns (bytes memory resultData);
                                /// @dev Execute an arbitrary delegatecall, in the context of this puppet.
                                ///      Only an authority can call this.
                                /// @param target The call target.
                                /// @param callData The call data.
                                /// @return resultData The data returned by the call.
                                function executeDelegateCall(
                                    address payable target,
                                    bytes calldata callData
                                )
                                    external
                                    payable
                                    returns (bytes memory resultData);
                                /// @dev Allows the puppet to receive ETH.
                                receive() external payable;
                                /// @dev Fetch the immutable owner/deployer of this contract.
                                /// @return owner_ The immutable owner/deployer/
                                function owner() external view returns (address owner_);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/AuthorizableV06.sol";
                            /// @dev A contract with a `die()` function.
                            interface IKillable {
                                function die() external;
                            }
                            /// @dev Deployer contract for ERC20 transformers.
                            ///      Only authorities may call `deploy()` and `kill()`.
                            contract TransformerDeployer is
                                AuthorizableV06
                            {
                                /// @dev Emitted when a contract is deployed via `deploy()`.
                                /// @param deployedAddress The address of the deployed contract.
                                /// @param nonce The deployment nonce.
                                /// @param sender The caller of `deploy()`.
                                event Deployed(address deployedAddress, uint256 nonce, address sender);
                                /// @dev Emitted when a contract is killed via `kill()`.
                                /// @param target The address of the contract being killed..
                                /// @param sender The caller of `kill()`.
                                event Killed(address target, address sender);
                                // @dev The current nonce of this contract.
                                uint256 public nonce = 1;
                                // @dev Mapping of deployed contract address to deployment nonce.
                                mapping (address => uint256) public toDeploymentNonce;
                                /// @dev Create this contract and register authorities.
                                constructor(address[] memory authorities) public {
                                    for (uint256 i = 0; i < authorities.length; ++i) {
                                        _addAuthorizedAddress(authorities[i]);
                                    }
                                }
                                /// @dev Deploy a new contract. Only callable by an authority.
                                ///      Any attached ETH will also be forwarded.
                                function deploy(bytes memory bytecode)
                                    public
                                    payable
                                    onlyAuthorized
                                    returns (address deployedAddress)
                                {
                                    uint256 deploymentNonce = nonce;
                                    nonce += 1;
                                    assembly {
                                        deployedAddress := create(callvalue(), add(bytecode, 32), mload(bytecode))
                                    }
                                    toDeploymentNonce[deployedAddress] = deploymentNonce;
                                    emit Deployed(deployedAddress, deploymentNonce, msg.sender);
                                }
                                /// @dev Call `die()` on a contract. Only callable by an authority.
                                function kill(IKillable target)
                                    public
                                    onlyAuthorized
                                {
                                    target.die();
                                    emit Killed(address(target), msg.sender);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            /// @dev Basic interface for a feature contract.
                            interface IFeature {
                                // solhint-disable func-name-mixedcase
                                /// @dev The name of this feature set.
                                function FEATURE_NAME() external view returns (string memory name);
                                /// @dev The version of this feature set.
                                function FEATURE_VERSION() external view returns (uint256 version);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/interfaces/IOwnableV06.sol";
                            // solhint-disable no-empty-blocks
                            /// @dev Owner management and migration features.
                            interface IOwnable is
                                IOwnableV06
                            {
                                /// @dev Emitted when `migrate()` is called.
                                /// @param caller The caller of `migrate()`.
                                /// @param migrator The migration contract.
                                /// @param newOwner The address of the new owner.
                                event Migrated(address caller, address migrator, address newOwner);
                                /// @dev Execute a migration function in the context of the ZeroEx contract.
                                ///      The result of the function being called should be the magic bytes
                                ///      0x2c64c5ef (`keccack('MIGRATE_SUCCESS')`). Only callable by the owner.
                                ///      The owner will be temporarily set to `address(this)` inside the call.
                                ///      Before returning, the owner will be set to `newOwner`.
                                /// @param target The migrator contract address.
                                /// @param newOwner The address of the new owner.
                                /// @param data The call data.
                                function migrate(address target, bytes calldata data, address newOwner) external;
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            /// @dev Basic registry management features.
                            interface ISimpleFunctionRegistry {
                                /// @dev A function implementation was updated via `extend()` or `rollback()`.
                                /// @param selector The function selector.
                                /// @param oldImpl The implementation contract address being replaced.
                                /// @param newImpl The replacement implementation contract address.
                                event ProxyFunctionUpdated(bytes4 indexed selector, address oldImpl, address newImpl);
                                /// @dev Roll back to a prior implementation of a function.
                                /// @param selector The function selector.
                                /// @param targetImpl The address of an older implementation of the function.
                                function rollback(bytes4 selector, address targetImpl) external;
                                /// @dev Register or replace a function.
                                /// @param selector The function selector.
                                /// @param impl The implementation contract for the function.
                                function extend(bytes4 selector, address impl) external;
                                /// @dev Retrieve the length of the rollback history for a function.
                                /// @param selector The function selector.
                                /// @return rollbackLength The number of items in the rollback history for
                                ///         the function.
                                function getRollbackLength(bytes4 selector)
                                    external
                                    view
                                    returns (uint256 rollbackLength);
                                /// @dev Retrieve an entry in the rollback history for a function.
                                /// @param selector The function selector.
                                /// @param idx The index in the rollback history.
                                /// @return impl An implementation address for the function at
                                ///         index `idx`.
                                function getRollbackEntryAtIndex(bytes4 selector, uint256 idx)
                                    external
                                    view
                                    returns (address impl);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            /// @dev Feature that allows spending token allowances.
                            interface ITokenSpender {
                                /// @dev Transfers ERC20 tokens from `owner` to `to`.
                                ///      Only callable from within.
                                /// @param token The token to spend.
                                /// @param owner The owner of the tokens.
                                /// @param to The recipient of the tokens.
                                /// @param amount The amount of `token` to transfer.
                                function _spendERC20Tokens(
                                    IERC20TokenV06 token,
                                    address owner,
                                    address to,
                                    uint256 amount
                                )
                                    external;
                                /// @dev Gets the maximum amount of an ERC20 token `token` that can be
                                ///      pulled from `owner`.
                                /// @param token The token to spend.
                                /// @param owner The owner of the tokens.
                                /// @return amount The amount of tokens that can be pulled.
                                function getSpendableERC20BalanceOf(IERC20TokenV06 token, address owner)
                                    external
                                    view
                                    returns (uint256 amount);
                                /// @dev Get the address of the allowance target.
                                /// @return target The target of token allowances.
                                function getAllowanceTarget() external view returns (address target);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            interface IERC20TokenV06 {
                                // solhint-disable no-simple-event-func-name
                                event Transfer(
                                    address indexed from,
                                    address indexed to,
                                    uint256 value
                                );
                                event Approval(
                                    address indexed owner,
                                    address indexed spender,
                                    uint256 value
                                );
                                /// @dev send `value` token to `to` from `msg.sender`
                                /// @param to The address of the recipient
                                /// @param value The amount of token to be transferred
                                /// @return True if transfer was successful
                                function transfer(address to, uint256 value)
                                    external
                                    returns (bool);
                                /// @dev send `value` token to `to` from `from` on the condition it is approved by `from`
                                /// @param from The address of the sender
                                /// @param to The address of the recipient
                                /// @param value The amount of token to be transferred
                                /// @return True if transfer was successful
                                function transferFrom(
                                    address from,
                                    address to,
                                    uint256 value
                                )
                                    external
                                    returns (bool);
                                /// @dev `msg.sender` approves `spender` to spend `value` tokens
                                /// @param spender The address of the account able to transfer the tokens
                                /// @param value The amount of wei to be approved for transfer
                                /// @return Always true if the call has enough gas to complete execution
                                function approve(address spender, uint256 value)
                                    external
                                    returns (bool);
                                /// @dev Query total supply of token
                                /// @return Total supply of token
                                function totalSupply()
                                    external
                                    view
                                    returns (uint256);
                                /// @dev Get the balance of `owner`.
                                /// @param owner The address from which the balance will be retrieved
                                /// @return Balance of owner
                                function balanceOf(address owner)
                                    external
                                    view
                                    returns (uint256);
                                /// @dev Get the allowance for `spender` to spend from `owner`.
                                /// @param owner The address of the account owning tokens
                                /// @param spender The address of the account able to transfer the tokens
                                /// @return Amount of remaining tokens allowed to spent
                                function allowance(address owner, address spender)
                                    external
                                    view
                                    returns (uint256);
                                /// @dev Get the number of decimals this token has.
                                function decimals()
                                    external
                                    view
                                    returns (uint8);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "../transformers/IERC20Transformer.sol";
                            import "../external/IFlashWallet.sol";
                            /// @dev Feature to composably transform between ERC20 tokens.
                            interface ITransformERC20 {
                                /// @dev Defines a transformation to run in `transformERC20()`.
                                struct Transformation {
                                    // The deployment nonce for the transformer.
                                    // The address of the transformer contract will be derived from this
                                    // value.
                                    uint32 deploymentNonce;
                                    // Arbitrary data to pass to the transformer.
                                    bytes data;
                                }
                                /// @dev Raised upon a successful `transformERC20`.
                                /// @param taker The taker (caller) address.
                                /// @param inputToken The token being provided by the taker.
                                ///        If `0xeee...`, ETH is implied and should be provided with the call.`
                                /// @param outputToken The token to be acquired by the taker.
                                ///        `0xeee...` implies ETH.
                                /// @param inputTokenAmount The amount of `inputToken` to take from the taker.
                                /// @param outputTokenAmount The amount of `outputToken` received by the taker.
                                event TransformedERC20(
                                    address indexed taker,
                                    address inputToken,
                                    address outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 outputTokenAmount
                                );
                                /// @dev Raised when `setTransformerDeployer()` is called.
                                /// @param transformerDeployer The new deployer address.
                                event TransformerDeployerUpdated(address transformerDeployer);
                                /// @dev Replace the allowed deployer for transformers.
                                ///      Only callable by the owner.
                                /// @param transformerDeployer The address of the trusted deployer for transformers.
                                function setTransformerDeployer(address transformerDeployer)
                                    external;
                                /// @dev Deploy a new flash wallet instance and replace the current one with it.
                                ///      Useful if we somehow break the current wallet instance.
                                ///      Anyone can call this.
                                /// @return wallet The new wallet instance.
                                function createTransformWallet()
                                    external
                                    returns (IFlashWallet wallet);
                                /// @dev Executes a series of transformations to convert an ERC20 `inputToken`
                                ///      to an ERC20 `outputToken`.
                                /// @param inputToken The token being provided by the sender.
                                ///        If `0xeee...`, ETH is implied and should be provided with the call.`
                                /// @param outputToken The token to be acquired by the sender.
                                ///        `0xeee...` implies ETH.
                                /// @param inputTokenAmount The amount of `inputToken` to take from the sender.
                                /// @param minOutputTokenAmount The minimum amount of `outputToken` the sender
                                ///        must receive for the entire transformation to succeed.
                                /// @param transformations The transformations to execute on the token balance(s)
                                ///        in sequence.
                                /// @return outputTokenAmount The amount of `outputToken` received by the sender.
                                function transformERC20(
                                    IERC20TokenV06 inputToken,
                                    IERC20TokenV06 outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 minOutputTokenAmount,
                                    Transformation[] calldata transformations
                                )
                                    external
                                    payable
                                    returns (uint256 outputTokenAmount);
                                /// @dev Internal version of `transformERC20()`. Only callable from within.
                                /// @param callDataHash Hash of the ingress calldata.
                                /// @param taker The taker address.
                                /// @param inputToken The token being provided by the taker.
                                ///        If `0xeee...`, ETH is implied and should be provided with the call.`
                                /// @param outputToken The token to be acquired by the taker.
                                ///        `0xeee...` implies ETH.
                                /// @param inputTokenAmount The amount of `inputToken` to take from the taker.
                                /// @param minOutputTokenAmount The minimum amount of `outputToken` the taker
                                ///        must receive for the entire transformation to succeed.
                                /// @param transformations The transformations to execute on the token balance(s)
                                ///        in sequence.
                                /// @return outputTokenAmount The amount of `outputToken` received by the taker.
                                function _transformERC20(
                                    bytes32 callDataHash,
                                    address payable taker,
                                    IERC20TokenV06 inputToken,
                                    IERC20TokenV06 outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 minOutputTokenAmount,
                                    Transformation[] calldata transformations
                                )
                                    external
                                    payable
                                    returns (uint256 outputTokenAmount);
                                /// @dev Return the current wallet instance that will serve as the execution
                                ///      context for transformations.
                                /// @return wallet The wallet instance.
                                function getTransformWallet()
                                    external
                                    view
                                    returns (IFlashWallet wallet);
                                /// @dev Return the allowed deployer for transformers.
                                /// @return deployer The transform deployer address.
                                function getTransformerDeployer()
                                    external
                                    view
                                    returns (address deployer);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            /// @dev A transformation callback used in `TransformERC20.transformERC20()`.
                            interface IERC20Transformer {
                                /// @dev Called from `TransformERC20.transformERC20()`. This will be
                                ///      delegatecalled in the context of the FlashWallet instance being used.
                                /// @param callDataHash The hash of the `TransformERC20.transformERC20()` calldata.
                                /// @param taker The taker address (caller of `TransformERC20.transformERC20()`).
                                /// @param data Arbitrary data to pass to the transformer.
                                /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
                                function transform(
                                    bytes32 callDataHash,
                                    address payable taker,
                                    bytes calldata data
                                )
                                    external
                                    returns (bytes4 success);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "../fixins/FixinCommon.sol";
                            import "../errors/LibOwnableRichErrors.sol";
                            import "../storage/LibOwnableStorage.sol";
                            import "../migrations/LibBootstrap.sol";
                            import "../migrations/LibMigrate.sol";
                            import "./IFeature.sol";
                            import "./IOwnable.sol";
                            import "./SimpleFunctionRegistry.sol";
                            /// @dev Owner management features.
                            contract Ownable is
                                IFeature,
                                IOwnable,
                                FixinCommon
                            {
                                // solhint-disable
                                /// @dev Name of this feature.
                                string public constant override FEATURE_NAME = "Ownable";
                                /// @dev Version of this feature.
                                uint256 public immutable override FEATURE_VERSION = _encodeVersion(1, 0, 0);
                                /// @dev The deployed address of this contract.
                                address immutable private _implementation;
                                // solhint-enable
                                using LibRichErrorsV06 for bytes;
                                constructor() public {
                                    _implementation = address(this);
                                }
                                /// @dev Initializes this feature. The intial owner will be set to this (ZeroEx)
                                ///      to allow the bootstrappers to call `extend()`. Ownership should be
                                ///      transferred to the real owner by the bootstrapper after
                                ///      bootstrapping is complete.
                                /// @return success Magic bytes if successful.
                                function bootstrap() external returns (bytes4 success) {
                                    // Set the owner to ourselves to allow bootstrappers to call `extend()`.
                                    LibOwnableStorage.getStorage().owner = address(this);
                                    // Register feature functions.
                                    SimpleFunctionRegistry(address(this))._extendSelf(this.transferOwnership.selector, _implementation);
                                    SimpleFunctionRegistry(address(this))._extendSelf(this.owner.selector, _implementation);
                                    SimpleFunctionRegistry(address(this))._extendSelf(this.migrate.selector, _implementation);
                                    return LibBootstrap.BOOTSTRAP_SUCCESS;
                                }
                                /// @dev Change the owner of this contract.
                                ///      Only directly callable by the owner.
                                /// @param newOwner New owner address.
                                function transferOwnership(address newOwner)
                                    external
                                    override
                                    onlyOwner
                                {
                                    LibOwnableStorage.Storage storage proxyStor = LibOwnableStorage.getStorage();
                                    if (newOwner == address(0)) {
                                        LibOwnableRichErrors.TransferOwnerToZeroError().rrevert();
                                    } else {
                                        proxyStor.owner = newOwner;
                                        emit OwnershipTransferred(msg.sender, newOwner);
                                    }
                                }
                                /// @dev Execute a migration function in the context of the ZeroEx contract.
                                ///      The result of the function being called should be the magic bytes
                                ///      0x2c64c5ef (`keccack('MIGRATE_SUCCESS')`). Only callable by the owner.
                                ///      Temporarily sets the owner to ourselves so we can perform admin functions.
                                ///      Before returning, the owner will be set to `newOwner`.
                                /// @param target The migrator contract address.
                                /// @param data The call data.
                                /// @param newOwner The address of the new owner.
                                function migrate(address target, bytes calldata data, address newOwner)
                                    external
                                    override
                                    onlyOwner
                                {
                                    if (newOwner == address(0)) {
                                        LibOwnableRichErrors.TransferOwnerToZeroError().rrevert();
                                    }
                                    LibOwnableStorage.Storage storage stor = LibOwnableStorage.getStorage();
                                    // The owner will be temporarily set to `address(this)` inside the call.
                                    stor.owner = address(this);
                                    // Perform the migration.
                                    LibMigrate.delegatecallMigrateFunction(target, data);
                                    // Update the owner.
                                    stor.owner = newOwner;
                                    emit Migrated(msg.sender, target, newOwner);
                                }
                                /// @dev Get the owner of this contract.
                                /// @return owner_ The owner of this contract.
                                function owner() external override view returns (address owner_) {
                                    return LibOwnableStorage.getStorage().owner;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "../errors/LibCommonRichErrors.sol";
                            import "../errors/LibOwnableRichErrors.sol";
                            import "../features/IOwnable.sol";
                            /// @dev Common feature utilities.
                            contract FixinCommon {
                                using LibRichErrorsV06 for bytes;
                                /// @dev The caller must be this contract.
                                modifier onlySelf() virtual {
                                    if (msg.sender != address(this)) {
                                        LibCommonRichErrors.OnlyCallableBySelfError(msg.sender).rrevert();
                                    }
                                    _;
                                }
                                /// @dev The caller of this function must be the owner.
                                modifier onlyOwner() virtual {
                                    {
                                        address owner = IOwnable(address(this)).owner();
                                        if (msg.sender != owner) {
                                            LibOwnableRichErrors.OnlyOwnerError(
                                                msg.sender,
                                                owner
                                            ).rrevert();
                                        }
                                    }
                                    _;
                                }
                                /// @dev Encode a feature version as a `uint256`.
                                /// @param major The major version number of the feature.
                                /// @param minor The minor version number of the feature.
                                /// @param revision The revision number of the feature.
                                /// @return encodedVersion The encoded version number.
                                function _encodeVersion(uint32 major, uint32 minor, uint32 revision)
                                    internal
                                    pure
                                    returns (uint256 encodedVersion)
                                {
                                    return (major << 64) | (minor << 32) | revision;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "./LibStorage.sol";
                            /// @dev Storage helpers for the `Ownable` feature.
                            library LibOwnableStorage {
                                /// @dev Storage bucket for this feature.
                                struct Storage {
                                    // The owner of this contract.
                                    address owner;
                                }
                                /// @dev Get the storage bucket for this contract.
                                function getStorage() internal pure returns (Storage storage stor) {
                                    uint256 storageSlot = LibStorage.getStorageSlot(
                                        LibStorage.StorageId.Ownable
                                    );
                                    // Dip into assembly to change the slot pointed to by the local
                                    // variable `stor`.
                                    // See https://solidity.readthedocs.io/en/v0.6.8/assembly.html?highlight=slot#access-to-external-variables-functions-and-libraries
                                    assembly { stor_slot := storageSlot }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "../errors/LibOwnableRichErrors.sol";
                            library LibMigrate {
                                /// @dev Magic bytes returned by a migrator to indicate success.
                                ///      This is `keccack('MIGRATE_SUCCESS')`.
                                bytes4 internal constant MIGRATE_SUCCESS = 0x2c64c5ef;
                                using LibRichErrorsV06 for bytes;
                                /// @dev Perform a delegatecall and ensure it returns the magic bytes.
                                /// @param target The call target.
                                /// @param data The call data.
                                function delegatecallMigrateFunction(
                                    address target,
                                    bytes memory data
                                )
                                    internal
                                {
                                    (bool success, bytes memory resultData) = target.delegatecall(data);
                                    if (!success ||
                                        resultData.length != 32 ||
                                        abi.decode(resultData, (bytes4)) != MIGRATE_SUCCESS)
                                    {
                                        LibOwnableRichErrors.MigrateCallFailedError(target, resultData).rrevert();
                                    }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "../fixins/FixinCommon.sol";
                            import "../storage/LibProxyStorage.sol";
                            import "../storage/LibSimpleFunctionRegistryStorage.sol";
                            import "../errors/LibSimpleFunctionRegistryRichErrors.sol";
                            import "../migrations/LibBootstrap.sol";
                            import "./IFeature.sol";
                            import "./ISimpleFunctionRegistry.sol";
                            /// @dev Basic registry management features.
                            contract SimpleFunctionRegistry is
                                IFeature,
                                ISimpleFunctionRegistry,
                                FixinCommon
                            {
                                // solhint-disable
                                /// @dev Name of this feature.
                                string public constant override FEATURE_NAME = "SimpleFunctionRegistry";
                                /// @dev Version of this feature.
                                uint256 public immutable override FEATURE_VERSION = _encodeVersion(1, 0, 0);
                                /// @dev The deployed address of this contract.
                                address private immutable _implementation;
                                // solhint-enable
                                using LibRichErrorsV06 for bytes;
                                constructor() public {
                                    _implementation = address(this);
                                }
                                /// @dev Initializes this feature, registering its own functions.
                                /// @return success Magic bytes if successful.
                                function bootstrap()
                                    external
                                    returns (bytes4 success)
                                {
                                    // Register the registration functions (inception vibes).
                                    _extend(this.extend.selector, _implementation);
                                    _extend(this._extendSelf.selector, _implementation);
                                    // Register the rollback function.
                                    _extend(this.rollback.selector, _implementation);
                                    // Register getters.
                                    _extend(this.getRollbackLength.selector, _implementation);
                                    _extend(this.getRollbackEntryAtIndex.selector, _implementation);
                                    return LibBootstrap.BOOTSTRAP_SUCCESS;
                                }
                                /// @dev Roll back to a prior implementation of a function.
                                ///      Only directly callable by an authority.
                                /// @param selector The function selector.
                                /// @param targetImpl The address of an older implementation of the function.
                                function rollback(bytes4 selector, address targetImpl)
                                    external
                                    override
                                    onlyOwner
                                {
                                    (
                                        LibSimpleFunctionRegistryStorage.Storage storage stor,
                                        LibProxyStorage.Storage storage proxyStor
                                    ) = _getStorages();
                                    address currentImpl = proxyStor.impls[selector];
                                    if (currentImpl == targetImpl) {
                                        // Do nothing if already at targetImpl.
                                        return;
                                    }
                                    // Walk history backwards until we find the target implementation.
                                    address[] storage history = stor.implHistory[selector];
                                    uint256 i = history.length;
                                    for (; i > 0; --i) {
                                        address impl = history[i - 1];
                                        history.pop();
                                        if (impl == targetImpl) {
                                            break;
                                        }
                                    }
                                    if (i == 0) {
                                        LibSimpleFunctionRegistryRichErrors.NotInRollbackHistoryError(
                                            selector,
                                            targetImpl
                                        ).rrevert();
                                    }
                                    proxyStor.impls[selector] = targetImpl;
                                    emit ProxyFunctionUpdated(selector, currentImpl, targetImpl);
                                }
                                /// @dev Register or replace a function.
                                ///      Only directly callable by an authority.
                                /// @param selector The function selector.
                                /// @param impl The implementation contract for the function.
                                function extend(bytes4 selector, address impl)
                                    external
                                    override
                                    onlyOwner
                                {
                                    _extend(selector, impl);
                                }
                                /// @dev Register or replace a function.
                                ///      Only callable from within.
                                ///      This function is only used during the bootstrap process and
                                ///      should be deregistered by the deployer after bootstrapping is
                                ///      complete.
                                /// @param selector The function selector.
                                /// @param impl The implementation contract for the function.
                                function _extendSelf(bytes4 selector, address impl)
                                    external
                                    onlySelf
                                {
                                    _extend(selector, impl);
                                }
                                /// @dev Retrieve the length of the rollback history for a function.
                                /// @param selector The function selector.
                                /// @return rollbackLength The number of items in the rollback history for
                                ///         the function.
                                function getRollbackLength(bytes4 selector)
                                    external
                                    override
                                    view
                                    returns (uint256 rollbackLength)
                                {
                                    return LibSimpleFunctionRegistryStorage.getStorage().implHistory[selector].length;
                                }
                                /// @dev Retrieve an entry in the rollback history for a function.
                                /// @param selector The function selector.
                                /// @param idx The index in the rollback history.
                                /// @return impl An implementation address for the function at
                                ///         index `idx`.
                                function getRollbackEntryAtIndex(bytes4 selector, uint256 idx)
                                    external
                                    override
                                    view
                                    returns (address impl)
                                {
                                    return LibSimpleFunctionRegistryStorage.getStorage().implHistory[selector][idx];
                                }
                                /// @dev Register or replace a function.
                                /// @param selector The function selector.
                                /// @param impl The implementation contract for the function.
                                function _extend(bytes4 selector, address impl)
                                    private
                                {
                                    (
                                        LibSimpleFunctionRegistryStorage.Storage storage stor,
                                        LibProxyStorage.Storage storage proxyStor
                                    ) = _getStorages();
                                    address oldImpl = proxyStor.impls[selector];
                                    address[] storage history = stor.implHistory[selector];
                                    history.push(oldImpl);
                                    proxyStor.impls[selector] = impl;
                                    emit ProxyFunctionUpdated(selector, oldImpl, impl);
                                }
                                /// @dev Get the storage buckets for this feature and the proxy.
                                /// @return stor Storage bucket for this feature.
                                /// @return proxyStor age bucket for the proxy.
                                function _getStorages()
                                    private
                                    pure
                                    returns (
                                        LibSimpleFunctionRegistryStorage.Storage storage stor,
                                        LibProxyStorage.Storage storage proxyStor
                                    )
                                {
                                    return (
                                        LibSimpleFunctionRegistryStorage.getStorage(),
                                        LibProxyStorage.getStorage()
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "./LibStorage.sol";
                            /// @dev Storage helpers for the `SimpleFunctionRegistry` feature.
                            library LibSimpleFunctionRegistryStorage {
                                /// @dev Storage bucket for this feature.
                                struct Storage {
                                    // Mapping of function selector -> implementation history.
                                    mapping(bytes4 => address[]) implHistory;
                                }
                                /// @dev Get the storage bucket for this contract.
                                function getStorage() internal pure returns (Storage storage stor) {
                                    uint256 storageSlot = LibStorage.getStorageSlot(
                                        LibStorage.StorageId.SimpleFunctionRegistry
                                    );
                                    // Dip into assembly to change the slot pointed to by the local
                                    // variable `stor`.
                                    // See https://solidity.readthedocs.io/en/v0.6.8/assembly.html?highlight=slot#access-to-external-variables-functions-and-libraries
                                    assembly { stor_slot := storageSlot }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
                            import "../errors/LibSpenderRichErrors.sol";
                            import "../fixins/FixinCommon.sol";
                            import "../migrations/LibMigrate.sol";
                            import "../external/IAllowanceTarget.sol";
                            import "../storage/LibTokenSpenderStorage.sol";
                            import "./ITokenSpender.sol";
                            import "./IFeature.sol";
                            import "./ISimpleFunctionRegistry.sol";
                            /// @dev Feature that allows spending token allowances.
                            contract TokenSpender is
                                IFeature,
                                ITokenSpender,
                                FixinCommon
                            {
                                // solhint-disable
                                /// @dev Name of this feature.
                                string public constant override FEATURE_NAME = "TokenSpender";
                                /// @dev Version of this feature.
                                uint256 public immutable override FEATURE_VERSION = _encodeVersion(1, 0, 0);
                                /// @dev The implementation address of this feature.
                                address private immutable _implementation;
                                // solhint-enable
                                using LibRichErrorsV06 for bytes;
                                constructor() public {
                                    _implementation = address(this);
                                }
                                /// @dev Initialize and register this feature. Should be delegatecalled
                                ///      into during a `Migrate.migrate()`.
                                /// @param allowanceTarget An `allowanceTarget` instance, configured to have
                                ///        the ZeroeEx contract as an authority.
                                /// @return success `MIGRATE_SUCCESS` on success.
                                function migrate(IAllowanceTarget allowanceTarget) external returns (bytes4 success) {
                                    LibTokenSpenderStorage.getStorage().allowanceTarget = allowanceTarget;
                                    ISimpleFunctionRegistry(address(this))
                                        .extend(this.getAllowanceTarget.selector, _implementation);
                                    ISimpleFunctionRegistry(address(this))
                                        .extend(this._spendERC20Tokens.selector, _implementation);
                                    ISimpleFunctionRegistry(address(this))
                                        .extend(this.getSpendableERC20BalanceOf.selector, _implementation);
                                    return LibMigrate.MIGRATE_SUCCESS;
                                }
                                /// @dev Transfers ERC20 tokens from `owner` to `to`. Only callable from within.
                                /// @param token The token to spend.
                                /// @param owner The owner of the tokens.
                                /// @param to The recipient of the tokens.
                                /// @param amount The amount of `token` to transfer.
                                function _spendERC20Tokens(
                                    IERC20TokenV06 token,
                                    address owner,
                                    address to,
                                    uint256 amount
                                )
                                    external
                                    override
                                    onlySelf
                                {
                                    IAllowanceTarget spender = LibTokenSpenderStorage.getStorage().allowanceTarget;
                                    // Have the allowance target execute an ERC20 `transferFrom()`.
                                    (bool didSucceed, bytes memory resultData) = address(spender).call(
                                        abi.encodeWithSelector(
                                            IAllowanceTarget.executeCall.selector,
                                            address(token),
                                            abi.encodeWithSelector(
                                                IERC20TokenV06.transferFrom.selector,
                                                owner,
                                                to,
                                                amount
                                            )
                                        )
                                    );
                                    if (didSucceed) {
                                        resultData = abi.decode(resultData, (bytes));
                                    }
                                    if (!didSucceed || !LibERC20TokenV06.isSuccessfulResult(resultData)) {
                                        LibSpenderRichErrors.SpenderERC20TransferFromFailedError(
                                            address(token),
                                            owner,
                                            to,
                                            amount,
                                            resultData
                                        ).rrevert();
                                    }
                                }
                                /// @dev Gets the maximum amount of an ERC20 token `token` that can be
                                ///      pulled from `owner` by the token spender.
                                /// @param token The token to spend.
                                /// @param owner The owner of the tokens.
                                /// @return amount The amount of tokens that can be pulled.
                                function getSpendableERC20BalanceOf(IERC20TokenV06 token, address owner)
                                    external
                                    override
                                    view
                                    returns (uint256 amount)
                                {
                                    return LibSafeMathV06.min256(
                                        token.allowance(owner, address(LibTokenSpenderStorage.getStorage().allowanceTarget)),
                                        token.balanceOf(owner)
                                    );
                                }
                                /// @dev Get the address of the allowance target.
                                /// @return target The target of token allowances.
                                function getAllowanceTarget()
                                    external
                                    override
                                    view
                                    returns (address target)
                                {
                                    return address(LibTokenSpenderStorage.getStorage().allowanceTarget);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./errors/LibRichErrorsV06.sol";
                            import "./errors/LibSafeMathRichErrorsV06.sol";
                            library LibSafeMathV06 {
                                function safeMul(uint256 a, uint256 b)
                                    internal
                                    pure
                                    returns (uint256)
                                {
                                    if (a == 0) {
                                        return 0;
                                    }
                                    uint256 c = a * b;
                                    if (c / a != b) {
                                        LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                                            LibSafeMathRichErrorsV06.BinOpErrorCodes.MULTIPLICATION_OVERFLOW,
                                            a,
                                            b
                                        ));
                                    }
                                    return c;
                                }
                                function safeDiv(uint256 a, uint256 b)
                                    internal
                                    pure
                                    returns (uint256)
                                {
                                    if (b == 0) {
                                        LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                                            LibSafeMathRichErrorsV06.BinOpErrorCodes.DIVISION_BY_ZERO,
                                            a,
                                            b
                                        ));
                                    }
                                    uint256 c = a / b;
                                    return c;
                                }
                                function safeSub(uint256 a, uint256 b)
                                    internal
                                    pure
                                    returns (uint256)
                                {
                                    if (b > a) {
                                        LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                                            LibSafeMathRichErrorsV06.BinOpErrorCodes.SUBTRACTION_UNDERFLOW,
                                            a,
                                            b
                                        ));
                                    }
                                    return a - b;
                                }
                                function safeAdd(uint256 a, uint256 b)
                                    internal
                                    pure
                                    returns (uint256)
                                {
                                    uint256 c = a + b;
                                    if (c < a) {
                                        LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                                            LibSafeMathRichErrorsV06.BinOpErrorCodes.ADDITION_OVERFLOW,
                                            a,
                                            b
                                        ));
                                    }
                                    return c;
                                }
                                function max256(uint256 a, uint256 b)
                                    internal
                                    pure
                                    returns (uint256)
                                {
                                    return a >= b ? a : b;
                                }
                                function min256(uint256 a, uint256 b)
                                    internal
                                    pure
                                    returns (uint256)
                                {
                                    return a < b ? a : b;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibSafeMathRichErrorsV06 {
                                // bytes4(keccak256("Uint256BinOpError(uint8,uint256,uint256)"))
                                bytes4 internal constant UINT256_BINOP_ERROR_SELECTOR =
                                    0xe946c1bb;
                                // bytes4(keccak256("Uint256DowncastError(uint8,uint256)"))
                                bytes4 internal constant UINT256_DOWNCAST_ERROR_SELECTOR =
                                    0xc996af7b;
                                enum BinOpErrorCodes {
                                    ADDITION_OVERFLOW,
                                    MULTIPLICATION_OVERFLOW,
                                    SUBTRACTION_UNDERFLOW,
                                    DIVISION_BY_ZERO
                                }
                                enum DowncastErrorCodes {
                                    VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT32,
                                    VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT64,
                                    VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT96
                                }
                                // solhint-disable func-name-mixedcase
                                function Uint256BinOpError(
                                    BinOpErrorCodes errorCode,
                                    uint256 a,
                                    uint256 b
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        UINT256_BINOP_ERROR_SELECTOR,
                                        errorCode,
                                        a,
                                        b
                                    );
                                }
                                function Uint256DowncastError(
                                    DowncastErrorCodes errorCode,
                                    uint256 a
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        UINT256_DOWNCAST_ERROR_SELECTOR,
                                        errorCode,
                                        a
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
                            import "./IERC20TokenV06.sol";
                            library LibERC20TokenV06 {
                                bytes constant private DECIMALS_CALL_DATA = hex"313ce567";
                                /// @dev Calls `IERC20TokenV06(token).approve()`.
                                ///      Reverts if the result fails `isSuccessfulResult()` or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param spender The address that receives an allowance.
                                /// @param allowance The allowance to set.
                                function compatApprove(
                                    IERC20TokenV06 token,
                                    address spender,
                                    uint256 allowance
                                )
                                    internal
                                {
                                    bytes memory callData = abi.encodeWithSelector(
                                        token.approve.selector,
                                        spender,
                                        allowance
                                    );
                                    _callWithOptionalBooleanResult(address(token), callData);
                                }
                                /// @dev Calls `IERC20TokenV06(token).approve()` and sets the allowance to the
                                ///      maximum if the current approval is not already >= an amount.
                                ///      Reverts if the result fails `isSuccessfulResult()` or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param spender The address that receives an allowance.
                                /// @param amount The minimum allowance needed.
                                function approveIfBelow(
                                    IERC20TokenV06 token,
                                    address spender,
                                    uint256 amount
                                )
                                    internal
                                {
                                    if (token.allowance(address(this), spender) < amount) {
                                        compatApprove(token, spender, uint256(-1));
                                    }
                                }
                                /// @dev Calls `IERC20TokenV06(token).transfer()`.
                                ///      Reverts if the result fails `isSuccessfulResult()` or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param to The address that receives the tokens
                                /// @param amount Number of tokens to transfer.
                                function compatTransfer(
                                    IERC20TokenV06 token,
                                    address to,
                                    uint256 amount
                                )
                                    internal
                                {
                                    bytes memory callData = abi.encodeWithSelector(
                                        token.transfer.selector,
                                        to,
                                        amount
                                    );
                                    _callWithOptionalBooleanResult(address(token), callData);
                                }
                                /// @dev Calls `IERC20TokenV06(token).transferFrom()`.
                                ///      Reverts if the result fails `isSuccessfulResult()` or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param from The owner of the tokens.
                                /// @param to The address that receives the tokens
                                /// @param amount Number of tokens to transfer.
                                function compatTransferFrom(
                                    IERC20TokenV06 token,
                                    address from,
                                    address to,
                                    uint256 amount
                                )
                                    internal
                                {
                                    bytes memory callData = abi.encodeWithSelector(
                                        token.transferFrom.selector,
                                        from,
                                        to,
                                        amount
                                    );
                                    _callWithOptionalBooleanResult(address(token), callData);
                                }
                                /// @dev Retrieves the number of decimals for a token.
                                ///      Returns `18` if the call reverts.
                                /// @param token The address of the token contract.
                                /// @return tokenDecimals The number of decimals places for the token.
                                function compatDecimals(IERC20TokenV06 token)
                                    internal
                                    view
                                    returns (uint8 tokenDecimals)
                                {
                                    tokenDecimals = 18;
                                    (bool didSucceed, bytes memory resultData) = address(token).staticcall(DECIMALS_CALL_DATA);
                                    if (didSucceed && resultData.length == 32) {
                                        tokenDecimals = uint8(LibBytesV06.readUint256(resultData, 0));
                                    }
                                }
                                /// @dev Retrieves the allowance for a token, owner, and spender.
                                ///      Returns `0` if the call reverts.
                                /// @param token The address of the token contract.
                                /// @param owner The owner of the tokens.
                                /// @param spender The address the spender.
                                /// @return allowance_ The allowance for a token, owner, and spender.
                                function compatAllowance(IERC20TokenV06 token, address owner, address spender)
                                    internal
                                    view
                                    returns (uint256 allowance_)
                                {
                                    (bool didSucceed, bytes memory resultData) = address(token).staticcall(
                                        abi.encodeWithSelector(
                                            token.allowance.selector,
                                            owner,
                                            spender
                                        )
                                    );
                                    if (didSucceed && resultData.length == 32) {
                                        allowance_ = LibBytesV06.readUint256(resultData, 0);
                                    }
                                }
                                /// @dev Retrieves the balance for a token owner.
                                ///      Returns `0` if the call reverts.
                                /// @param token The address of the token contract.
                                /// @param owner The owner of the tokens.
                                /// @return balance The token balance of an owner.
                                function compatBalanceOf(IERC20TokenV06 token, address owner)
                                    internal
                                    view
                                    returns (uint256 balance)
                                {
                                    (bool didSucceed, bytes memory resultData) = address(token).staticcall(
                                        abi.encodeWithSelector(
                                            token.balanceOf.selector,
                                            owner
                                        )
                                    );
                                    if (didSucceed && resultData.length == 32) {
                                        balance = LibBytesV06.readUint256(resultData, 0);
                                    }
                                }
                                /// @dev Check if the data returned by a non-static call to an ERC20 token
                                ///      is a successful result. Supported functions are `transfer()`,
                                ///      `transferFrom()`, and `approve()`.
                                /// @param resultData The raw data returned by a non-static call to the ERC20 token.
                                /// @return isSuccessful Whether the result data indicates success.
                                function isSuccessfulResult(bytes memory resultData)
                                    internal
                                    pure
                                    returns (bool isSuccessful)
                                {
                                    if (resultData.length == 0) {
                                        return true;
                                    }
                                    if (resultData.length == 32) {
                                        uint256 result = LibBytesV06.readUint256(resultData, 0);
                                        if (result == 1) {
                                            return true;
                                        }
                                    }
                                }
                                /// @dev Executes a call on address `target` with calldata `callData`
                                ///      and asserts that either nothing was returned or a single boolean
                                ///      was returned equal to `true`.
                                /// @param target The call target.
                                /// @param callData The abi-encoded call data.
                                function _callWithOptionalBooleanResult(
                                    address target,
                                    bytes memory callData
                                )
                                    private
                                {
                                    (bool didSucceed, bytes memory resultData) = target.call(callData);
                                    if (didSucceed && isSuccessfulResult(resultData)) {
                                        return;
                                    }
                                    LibRichErrorsV06.rrevert(resultData);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "./LibStorage.sol";
                            import "../external/IAllowanceTarget.sol";
                            /// @dev Storage helpers for the `TokenSpender` feature.
                            library LibTokenSpenderStorage {
                                /// @dev Storage bucket for this feature.
                                struct Storage {
                                    // Allowance target contract.
                                    IAllowanceTarget allowanceTarget;
                                }
                                /// @dev Get the storage bucket for this contract.
                                function getStorage() internal pure returns (Storage storage stor) {
                                    uint256 storageSlot = LibStorage.getStorageSlot(
                                        LibStorage.StorageId.TokenSpender
                                    );
                                    // Dip into assembly to change the slot pointed to by the local
                                    // variable `stor`.
                                    // See https://solidity.readthedocs.io/en/v0.6.8/assembly.html?highlight=slot#access-to-external-variables-functions-and-libraries
                                    assembly { stor_slot := storageSlot }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            import "../errors/LibTransformERC20RichErrors.sol";
                            import "../fixins/FixinCommon.sol";
                            import "../migrations/LibMigrate.sol";
                            import "../external/IFlashWallet.sol";
                            import "../external/FlashWallet.sol";
                            import "../storage/LibTransformERC20Storage.sol";
                            import "../transformers/IERC20Transformer.sol";
                            import "../transformers/LibERC20Transformer.sol";
                            import "./ITransformERC20.sol";
                            import "./ITokenSpender.sol";
                            import "./IFeature.sol";
                            import "./ISimpleFunctionRegistry.sol";
                            /// @dev Feature to composably transform between ERC20 tokens.
                            contract TransformERC20 is
                                IFeature,
                                ITransformERC20,
                                FixinCommon
                            {
                                /// @dev Stack vars for `_transformERC20Private()`.
                                struct TransformERC20PrivateState {
                                    IFlashWallet wallet;
                                    address transformerDeployer;
                                    uint256 takerOutputTokenBalanceBefore;
                                    uint256 takerOutputTokenBalanceAfter;
                                }
                                // solhint-disable
                                /// @dev Name of this feature.
                                string public constant override FEATURE_NAME = "TransformERC20";
                                /// @dev Version of this feature.
                                uint256 public immutable override FEATURE_VERSION = _encodeVersion(1, 0, 0);
                                /// @dev The implementation address of this feature.
                                address private immutable _implementation;
                                // solhint-enable
                                using LibSafeMathV06 for uint256;
                                using LibRichErrorsV06 for bytes;
                                constructor() public {
                                    _implementation = address(this);
                                }
                                /// @dev Initialize and register this feature.
                                ///      Should be delegatecalled by `Migrate.migrate()`.
                                /// @param transformerDeployer The trusted deployer for transformers.
                                /// @return success `LibMigrate.SUCCESS` on success.
                                function migrate(address transformerDeployer) external returns (bytes4 success) {
                                    ISimpleFunctionRegistry(address(this))
                                        .extend(this.getTransformerDeployer.selector, _implementation);
                                    ISimpleFunctionRegistry(address(this))
                                        .extend(this.createTransformWallet.selector, _implementation);
                                    ISimpleFunctionRegistry(address(this))
                                        .extend(this.getTransformWallet.selector, _implementation);
                                    ISimpleFunctionRegistry(address(this))
                                        .extend(this.setTransformerDeployer.selector, _implementation);
                                    ISimpleFunctionRegistry(address(this))
                                        .extend(this.transformERC20.selector, _implementation);
                                    ISimpleFunctionRegistry(address(this))
                                        .extend(this._transformERC20.selector, _implementation);
                                    createTransformWallet();
                                    LibTransformERC20Storage.getStorage().transformerDeployer = transformerDeployer;
                                    return LibMigrate.MIGRATE_SUCCESS;
                                }
                                /// @dev Replace the allowed deployer for transformers.
                                ///      Only callable by the owner.
                                /// @param transformerDeployer The address of the trusted deployer for transformers.
                                function setTransformerDeployer(address transformerDeployer)
                                    external
                                    override
                                    onlyOwner
                                {
                                    LibTransformERC20Storage.getStorage().transformerDeployer = transformerDeployer;
                                    emit TransformerDeployerUpdated(transformerDeployer);
                                }
                                /// @dev Return the allowed deployer for transformers.
                                /// @return deployer The transform deployer address.
                                function getTransformerDeployer()
                                    public
                                    override
                                    view
                                    returns (address deployer)
                                {
                                    return LibTransformERC20Storage.getStorage().transformerDeployer;
                                }
                                /// @dev Deploy a new wallet instance and replace the current one with it.
                                ///      Useful if we somehow break the current wallet instance.
                                ///      Anyone can call this.
                                /// @return wallet The new wallet instance.
                                function createTransformWallet()
                                    public
                                    override
                                    returns (IFlashWallet wallet)
                                {
                                    wallet = new FlashWallet();
                                    LibTransformERC20Storage.getStorage().wallet = wallet;
                                }
                                /// @dev Executes a series of transformations to convert an ERC20 `inputToken`
                                ///      to an ERC20 `outputToken`.
                                /// @param inputToken The token being provided by the sender.
                                ///        If `0xeee...`, ETH is implied and should be provided with the call.`
                                /// @param outputToken The token to be acquired by the sender.
                                ///        `0xeee...` implies ETH.
                                /// @param inputTokenAmount The amount of `inputToken` to take from the sender.
                                ///        If set to `uint256(-1)`, the entire spendable balance of the taker
                                ///        will be solt.
                                /// @param minOutputTokenAmount The minimum amount of `outputToken` the sender
                                ///        must receive for the entire transformation to succeed. If set to zero,
                                ///        the minimum output token transfer will not be asserted.
                                /// @param transformations The transformations to execute on the token balance(s)
                                ///        in sequence.
                                /// @return outputTokenAmount The amount of `outputToken` received by the sender.
                                function transformERC20(
                                    IERC20TokenV06 inputToken,
                                    IERC20TokenV06 outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 minOutputTokenAmount,
                                    Transformation[] memory transformations
                                )
                                    public
                                    override
                                    payable
                                    returns (uint256 outputTokenAmount)
                                {
                                    return _transformERC20Private(
                                        keccak256(msg.data),
                                        msg.sender,
                                        inputToken,
                                        outputToken,
                                        inputTokenAmount,
                                        minOutputTokenAmount,
                                        transformations
                                    );
                                }
                                /// @dev Internal version of `transformERC20()`. Only callable from within.
                                /// @param callDataHash Hash of the ingress calldata.
                                /// @param taker The taker address.
                                /// @param inputToken The token being provided by the taker.
                                ///        If `0xeee...`, ETH is implied and should be provided with the call.`
                                /// @param outputToken The token to be acquired by the taker.
                                ///        `0xeee...` implies ETH.
                                /// @param inputTokenAmount The amount of `inputToken` to take from the taker.
                                ///        If set to `uint256(-1)`, the entire spendable balance of the taker
                                ///        will be solt.
                                /// @param minOutputTokenAmount The minimum amount of `outputToken` the taker
                                ///        must receive for the entire transformation to succeed. If set to zero,
                                ///        the minimum output token transfer will not be asserted.
                                /// @param transformations The transformations to execute on the token balance(s)
                                ///        in sequence.
                                /// @return outputTokenAmount The amount of `outputToken` received by the taker.
                                function _transformERC20(
                                    bytes32 callDataHash,
                                    address payable taker,
                                    IERC20TokenV06 inputToken,
                                    IERC20TokenV06 outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 minOutputTokenAmount,
                                    Transformation[] memory transformations
                                )
                                    public
                                    override
                                    payable
                                    onlySelf
                                    returns (uint256 outputTokenAmount)
                                {
                                    return _transformERC20Private(
                                        callDataHash,
                                        taker,
                                        inputToken,
                                        outputToken,
                                        inputTokenAmount,
                                        minOutputTokenAmount,
                                        transformations
                                    );
                                }
                                /// @dev Private version of `transformERC20()`.
                                /// @param callDataHash Hash of the ingress calldata.
                                /// @param taker The taker address.
                                /// @param inputToken The token being provided by the taker.
                                ///        If `0xeee...`, ETH is implied and should be provided with the call.`
                                /// @param outputToken The token to be acquired by the taker.
                                ///        `0xeee...` implies ETH.
                                /// @param inputTokenAmount The amount of `inputToken` to take from the taker.
                                ///        If set to `uint256(-1)`, the entire spendable balance of the taker
                                ///        will be solt.
                                /// @param minOutputTokenAmount The minimum amount of `outputToken` the taker
                                ///        must receive for the entire transformation to succeed. If set to zero,
                                ///        the minimum output token transfer will not be asserted.
                                /// @param transformations The transformations to execute on the token balance(s)
                                ///        in sequence.
                                /// @return outputTokenAmount The amount of `outputToken` received by the taker.
                                function _transformERC20Private(
                                    bytes32 callDataHash,
                                    address payable taker,
                                    IERC20TokenV06 inputToken,
                                    IERC20TokenV06 outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 minOutputTokenAmount,
                                    Transformation[] memory transformations
                                )
                                    private
                                    returns (uint256 outputTokenAmount)
                                {
                                    // If the input token amount is -1, transform the taker's entire
                                    // spendable balance.
                                    if (inputTokenAmount == uint256(-1)) {
                                        inputTokenAmount = ITokenSpender(address(this))
                                            .getSpendableERC20BalanceOf(inputToken, taker);
                                    }
                                    TransformERC20PrivateState memory state;
                                    state.wallet = getTransformWallet();
                                    state.transformerDeployer = getTransformerDeployer();
                                    // Remember the initial output token balance of the taker.
                                    state.takerOutputTokenBalanceBefore =
                                        LibERC20Transformer.getTokenBalanceOf(outputToken, taker);
                                    // Pull input tokens from the taker to the wallet and transfer attached ETH.
                                    _transferInputTokensAndAttachedEth(
                                        inputToken,
                                        taker,
                                        address(state.wallet),
                                        inputTokenAmount
                                    );
                                    // Perform transformations.
                                    for (uint256 i = 0; i < transformations.length; ++i) {
                                        _executeTransformation(
                                            state.wallet,
                                            transformations[i],
                                            state.transformerDeployer,
                                            taker,
                                            callDataHash
                                        );
                                    }
                                    // Compute how much output token has been transferred to the taker.
                                    state.takerOutputTokenBalanceAfter =
                                        LibERC20Transformer.getTokenBalanceOf(outputToken, taker);
                                    if (state.takerOutputTokenBalanceAfter > state.takerOutputTokenBalanceBefore) {
                                        outputTokenAmount = state.takerOutputTokenBalanceAfter.safeSub(
                                            state.takerOutputTokenBalanceBefore
                                        );
                                    } else if (state.takerOutputTokenBalanceAfter < state.takerOutputTokenBalanceBefore) {
                                        LibTransformERC20RichErrors.NegativeTransformERC20OutputError(
                                            address(outputToken),
                                            state.takerOutputTokenBalanceBefore - state.takerOutputTokenBalanceAfter
                                        ).rrevert();
                                    }
                                    // Ensure enough output token has been sent to the taker.
                                    if (outputTokenAmount < minOutputTokenAmount) {
                                        LibTransformERC20RichErrors.IncompleteTransformERC20Error(
                                            address(outputToken),
                                            outputTokenAmount,
                                            minOutputTokenAmount
                                        ).rrevert();
                                    }
                                    // Emit an event.
                                    emit TransformedERC20(
                                        taker,
                                        address(inputToken),
                                        address(outputToken),
                                        inputTokenAmount,
                                        outputTokenAmount
                                    );
                                }
                                /// @dev Return the current wallet instance that will serve as the execution
                                ///      context for transformations.
                                /// @return wallet The wallet instance.
                                function getTransformWallet()
                                    public
                                    override
                                    view
                                    returns (IFlashWallet wallet)
                                {
                                    return LibTransformERC20Storage.getStorage().wallet;
                                }
                                /// @dev Transfer input tokens from the taker and any attached ETH to `to`
                                /// @param inputToken The token to pull from the taker.
                                /// @param from The from (taker) address.
                                /// @param to The recipient of tokens and ETH.
                                /// @param amount Amount of `inputToken` tokens to transfer.
                                function _transferInputTokensAndAttachedEth(
                                    IERC20TokenV06 inputToken,
                                    address from,
                                    address payable to,
                                    uint256 amount
                                )
                                    private
                                {
                                    // Transfer any attached ETH.
                                    if (msg.value != 0) {
                                        to.transfer(msg.value);
                                    }
                                    // Transfer input tokens.
                                    if (!LibERC20Transformer.isTokenETH(inputToken)) {
                                        // Token is not ETH, so pull ERC20 tokens.
                                        ITokenSpender(address(this))._spendERC20Tokens(
                                            inputToken,
                                            from,
                                            to,
                                            amount
                                        );
                                    } else if (msg.value < amount) {
                                         // Token is ETH, so the caller must attach enough ETH to the call.
                                        LibTransformERC20RichErrors.InsufficientEthAttachedError(
                                            msg.value,
                                            amount
                                        ).rrevert();
                                    }
                                }
                                /// @dev Executs a transformer in the context of `wallet`.
                                /// @param wallet The wallet instance.
                                /// @param transformation The transformation.
                                /// @param transformerDeployer The address of the transformer deployer.
                                /// @param taker The taker address.
                                /// @param callDataHash Hash of the calldata.
                                function _executeTransformation(
                                    IFlashWallet wallet,
                                    Transformation memory transformation,
                                    address transformerDeployer,
                                    address payable taker,
                                    bytes32 callDataHash
                                )
                                    private
                                {
                                    // Derive the transformer address from the deployment nonce.
                                    address payable transformer = LibERC20Transformer.getDeployedAddress(
                                        transformerDeployer,
                                        transformation.deploymentNonce
                                    );
                                    // Call `transformer.transform()` as the wallet.
                                    bytes memory resultData = wallet.executeDelegateCall(
                                        // The call target.
                                        transformer,
                                        // Call data.
                                        abi.encodeWithSelector(
                                            IERC20Transformer.transform.selector,
                                            callDataHash,
                                            taker,
                                            transformation.data
                                        )
                                    );
                                    // Ensure the transformer returned the magic bytes.
                                    if (resultData.length != 32 ||
                                        abi.decode(resultData, (bytes4)) != LibERC20Transformer.TRANSFORMER_SUCCESS
                                    ) {
                                        LibTransformERC20RichErrors.TransformerFailedError(
                                            transformer,
                                            transformation.data,
                                            resultData
                                        ).rrevert();
                                    }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "./LibStorage.sol";
                            import "../external/IFlashWallet.sol";
                            /// @dev Storage helpers for the `TokenSpender` feature.
                            library LibTransformERC20Storage {
                                /// @dev Storage bucket for this feature.
                                struct Storage {
                                    // The current wallet instance.
                                    IFlashWallet wallet;
                                    // The transformer deployer address.
                                    address transformerDeployer;
                                }
                                /// @dev Get the storage bucket for this contract.
                                function getStorage() internal pure returns (Storage storage stor) {
                                    uint256 storageSlot = LibStorage.getStorageSlot(
                                        LibStorage.StorageId.TransformERC20
                                    );
                                    // Dip into assembly to change the slot pointed to by the local
                                    // variable `stor`.
                                    // See https://solidity.readthedocs.io/en/v0.6.8/assembly.html?highlight=slot#access-to-external-variables-functions-and-libraries
                                    assembly { stor_slot := storageSlot }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
                            library LibERC20Transformer {
                                using LibERC20TokenV06 for IERC20TokenV06;
                                /// @dev ETH pseudo-token address.
                                address constant internal ETH_TOKEN_ADDRESS = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
                                /// @dev Return value indicating success in `IERC20Transformer.transform()`.
                                ///      This is just `keccak256('TRANSFORMER_SUCCESS')`.
                                bytes4 constant internal TRANSFORMER_SUCCESS = 0x13c9929e;
                                /// @dev Transfer ERC20 tokens and ETH.
                                /// @param token An ERC20 or the ETH pseudo-token address (`ETH_TOKEN_ADDRESS`).
                                /// @param to The recipient.
                                /// @param amount The transfer amount.
                                function transformerTransfer(
                                    IERC20TokenV06 token,
                                    address payable to,
                                    uint256 amount
                                )
                                    internal
                                {
                                    if (isTokenETH(token)) {
                                        to.transfer(amount);
                                    } else {
                                        token.compatTransfer(to, amount);
                                    }
                                }
                                /// @dev Check if a token is the ETH pseudo-token.
                                /// @param token The token to check.
                                /// @return isETH `true` if the token is the ETH pseudo-token.
                                function isTokenETH(IERC20TokenV06 token)
                                    internal
                                    pure
                                    returns (bool isETH)
                                {
                                    return address(token) == ETH_TOKEN_ADDRESS;
                                }
                                /// @dev Check the balance of an ERC20 token or ETH.
                                /// @param token An ERC20 or the ETH pseudo-token address (`ETH_TOKEN_ADDRESS`).
                                /// @param owner Holder of the tokens.
                                /// @return tokenBalance The balance of `owner`.
                                function getTokenBalanceOf(IERC20TokenV06 token, address owner)
                                    internal
                                    view
                                    returns (uint256 tokenBalance)
                                {
                                    if (isTokenETH(token)) {
                                        return owner.balance;
                                    }
                                    return token.balanceOf(owner);
                                }
                                /// @dev RLP-encode a 32-bit or less account nonce.
                                /// @param nonce A positive integer in the range 0 <= nonce < 2^32.
                                /// @return rlpNonce The RLP encoding.
                                function rlpEncodeNonce(uint32 nonce)
                                    internal
                                    pure
                                    returns (bytes memory rlpNonce)
                                {
                                    // See https://github.com/ethereum/wiki/wiki/RLP for RLP encoding rules.
                                    if (nonce == 0) {
                                        rlpNonce = new bytes(1);
                                        rlpNonce[0] = 0x80;
                                    } else if (nonce < 0x80) {
                                        rlpNonce = new bytes(1);
                                        rlpNonce[0] = byte(uint8(nonce));
                                    } else if (nonce <= 0xFF) {
                                        rlpNonce = new bytes(2);
                                        rlpNonce[0] = 0x81;
                                        rlpNonce[1] = byte(uint8(nonce));
                                    } else if (nonce <= 0xFFFF) {
                                        rlpNonce = new bytes(3);
                                        rlpNonce[0] = 0x82;
                                        rlpNonce[1] = byte(uint8((nonce & 0xFF00) >> 8));
                                        rlpNonce[2] = byte(uint8(nonce));
                                    } else if (nonce <= 0xFFFFFF) {
                                        rlpNonce = new bytes(4);
                                        rlpNonce[0] = 0x83;
                                        rlpNonce[1] = byte(uint8((nonce & 0xFF0000) >> 16));
                                        rlpNonce[2] = byte(uint8((nonce & 0xFF00) >> 8));
                                        rlpNonce[3] = byte(uint8(nonce));
                                    } else {
                                        rlpNonce = new bytes(5);
                                        rlpNonce[0] = 0x84;
                                        rlpNonce[1] = byte(uint8((nonce & 0xFF000000) >> 24));
                                        rlpNonce[2] = byte(uint8((nonce & 0xFF0000) >> 16));
                                        rlpNonce[3] = byte(uint8((nonce & 0xFF00) >> 8));
                                        rlpNonce[4] = byte(uint8(nonce));
                                    }
                                }
                                /// @dev Compute the expected deployment address by `deployer` at
                                ///      the nonce given by `deploymentNonce`.
                                /// @param deployer The address of the deployer.
                                /// @param deploymentNonce The nonce that the deployer had when deploying
                                ///        a contract.
                                /// @return deploymentAddress The deployment address.
                                function getDeployedAddress(address deployer, uint32 deploymentNonce)
                                    internal
                                    pure
                                    returns (address payable deploymentAddress)
                                {
                                    // The address of if a deployed contract is the lower 20 bytes of the
                                    // hash of the RLP-encoded deployer's account address + account nonce.
                                    // See: https://ethereum.stackexchange.com/questions/760/how-is-the-address-of-an-ethereum-contract-computed
                                    bytes memory rlpNonce = rlpEncodeNonce(deploymentNonce);
                                    return address(uint160(uint256(keccak256(abi.encodePacked(
                                        byte(uint8(0xC0 + 21 + rlpNonce.length)),
                                        byte(uint8(0x80 + 20)),
                                        deployer,
                                        rlpNonce
                                    )))));
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../ZeroEx.sol";
                            import "../features/IOwnable.sol";
                            import "../features/TokenSpender.sol";
                            import "../features/TransformERC20.sol";
                            import "../external/AllowanceTarget.sol";
                            import "./InitialMigration.sol";
                            /// @dev A contract for deploying and configuring the full ZeroEx contract.
                            contract FullMigration {
                                // solhint-disable no-empty-blocks,indent
                                /// @dev Features to add the the proxy contract.
                                struct Features {
                                    SimpleFunctionRegistry registry;
                                    Ownable ownable;
                                    TokenSpender tokenSpender;
                                    TransformERC20 transformERC20;
                                }
                                /// @dev Parameters needed to initialize features.
                                struct MigrateOpts {
                                    address transformerDeployer;
                                }
                                /// @dev The allowed caller of `deploy()`.
                                address public immutable deployer;
                                /// @dev The initial migration contract.
                                InitialMigration private _initialMigration;
                                /// @dev Instantiate this contract and set the allowed caller of `deploy()`
                                ///      to `deployer`.
                                /// @param deployer_ The allowed caller of `deploy()`.
                                constructor(address payable deployer_)
                                    public
                                {
                                    deployer = deployer_;
                                    // Create an initial migration contract with this contract set to the
                                    // allowed deployer.
                                    _initialMigration = new InitialMigration(address(this));
                                }
                                /// @dev Deploy the `ZeroEx` contract with the full feature set,
                                ///      transfer ownership to `owner`, then self-destruct.
                                /// @param owner The owner of the contract.
                                /// @param features Features to add to the proxy.
                                /// @return zeroEx The deployed and configured `ZeroEx` contract.
                                /// @param migrateOpts Parameters needed to initialize features.
                                function deploy(
                                    address payable owner,
                                    Features memory features,
                                    MigrateOpts memory migrateOpts
                                )
                                    public
                                    returns (ZeroEx zeroEx)
                                {
                                    require(msg.sender == deployer, "FullMigration/INVALID_SENDER");
                                    // Perform the initial migration with the owner set to this contract.
                                    zeroEx = _initialMigration.deploy(
                                        address(uint160(address(this))),
                                        InitialMigration.BootstrapFeatures({
                                            registry: features.registry,
                                            ownable: features.ownable
                                        })
                                    );
                                    // Add features.
                                    _addFeatures(zeroEx, owner, features, migrateOpts);
                                    // Transfer ownership to the real owner.
                                    IOwnable(address(zeroEx)).transferOwnership(owner);
                                    // Self-destruct.
                                    this.die(owner);
                                }
                                /// @dev Destroy this contract. Only callable from ourselves (from `deploy()`).
                                /// @param ethRecipient Receiver of any ETH in this contract.
                                function die(address payable ethRecipient)
                                    external
                                    virtual
                                {
                                    require(msg.sender == address(this), "FullMigration/INVALID_SENDER");
                                    // This contract should not hold any funds but we send
                                    // them to the ethRecipient just in case.
                                    selfdestruct(ethRecipient);
                                }
                                /// @dev Deploy and register features to the ZeroEx contract.
                                /// @param zeroEx The bootstrapped ZeroEx contract.
                                /// @param owner The ultimate owner of the ZeroEx contract.
                                /// @param features Features to add to the proxy.
                                /// @param migrateOpts Parameters needed to initialize features.
                                function _addFeatures(
                                    ZeroEx zeroEx,
                                    address owner,
                                    Features memory features,
                                    MigrateOpts memory migrateOpts
                                )
                                    private
                                {
                                    IOwnable ownable = IOwnable(address(zeroEx));
                                    // TokenSpender
                                    {
                                        // Create the allowance target.
                                        AllowanceTarget allowanceTarget = new AllowanceTarget();
                                        // Let the ZeroEx contract use the allowance target.
                                        allowanceTarget.addAuthorizedAddress(address(zeroEx));
                                        // Transfer ownership of the allowance target to the (real) owner.
                                        allowanceTarget.transferOwnership(owner);
                                        // Register the feature.
                                        ownable.migrate(
                                            address(features.tokenSpender),
                                            abi.encodeWithSelector(
                                                TokenSpender.migrate.selector,
                                                allowanceTarget
                                            ),
                                            address(this)
                                        );
                                    }
                                    // TransformERC20
                                    {
                                        // Register the feature.
                                        ownable.migrate(
                                            address(features.transformERC20),
                                            abi.encodeWithSelector(
                                                TransformERC20.migrate.selector,
                                                migrateOpts.transformerDeployer
                                            ),
                                            address(this)
                                        );
                                    }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../ZeroEx.sol";
                            import "../features/IBootstrap.sol";
                            import "../features/SimpleFunctionRegistry.sol";
                            import "../features/Ownable.sol";
                            import "./LibBootstrap.sol";
                            /// @dev A contract for deploying and configuring a minimal ZeroEx contract.
                            contract InitialMigration {
                                /// @dev Features to bootstrap into the the proxy contract.
                                struct BootstrapFeatures {
                                    SimpleFunctionRegistry registry;
                                    Ownable ownable;
                                }
                                /// @dev The allowed caller of `deploy()`. In production, this would be
                                ///      the governor.
                                address public immutable deployer;
                                /// @dev The real address of this contract.
                                address private immutable _implementation;
                                /// @dev Instantiate this contract and set the allowed caller of `deploy()`
                                ///      to `deployer_`.
                                /// @param deployer_ The allowed caller of `deploy()`.
                                constructor(address deployer_) public {
                                    deployer = deployer_;
                                    _implementation = address(this);
                                }
                                /// @dev Deploy the `ZeroEx` contract with the minimum feature set,
                                ///      transfers ownership to `owner`, then self-destructs.
                                ///      Only callable by `deployer` set in the contstructor.
                                /// @param owner The owner of the contract.
                                /// @param features Features to bootstrap into the proxy.
                                /// @return zeroEx The deployed and configured `ZeroEx` contract.
                                function deploy(address payable owner, BootstrapFeatures memory features)
                                    public
                                    virtual
                                    returns (ZeroEx zeroEx)
                                {
                                    // Must be called by the allowed deployer.
                                    require(msg.sender == deployer, "InitialMigration/INVALID_SENDER");
                                    // Deploy the ZeroEx contract, setting ourselves as the bootstrapper.
                                    zeroEx = new ZeroEx();
                                    // Bootstrap the initial feature set.
                                    IBootstrap(address(zeroEx)).bootstrap(
                                        address(this),
                                        abi.encodeWithSelector(this.bootstrap.selector, owner, features)
                                    );
                                    // Self-destruct. This contract should not hold any funds but we send
                                    // them to the owner just in case.
                                    this.die(owner);
                                }
                                /// @dev Sets up the initial state of the `ZeroEx` contract.
                                ///      The `ZeroEx` contract will delegatecall into this function.
                                /// @param owner The new owner of the ZeroEx contract.
                                /// @param features Features to bootstrap into the proxy.
                                /// @return success Magic bytes if successful.
                                function bootstrap(address owner, BootstrapFeatures memory features)
                                    public
                                    virtual
                                    returns (bytes4 success)
                                {
                                    // Deploy and migrate the initial features.
                                    // Order matters here.
                                    // Initialize Registry.
                                    LibBootstrap.delegatecallBootstrapFunction(
                                        address(features.registry),
                                        abi.encodeWithSelector(
                                            SimpleFunctionRegistry.bootstrap.selector
                                        )
                                    );
                                    // Initialize Ownable.
                                    LibBootstrap.delegatecallBootstrapFunction(
                                        address(features.ownable),
                                        abi.encodeWithSelector(
                                            Ownable.bootstrap.selector
                                        )
                                    );
                                    // De-register `SimpleFunctionRegistry._extendSelf`.
                                    SimpleFunctionRegistry(address(this)).rollback(
                                        SimpleFunctionRegistry._extendSelf.selector,
                                        address(0)
                                    );
                                    // Transfer ownership to the real owner.
                                    Ownable(address(this)).transferOwnership(owner);
                                    success = LibBootstrap.BOOTSTRAP_SUCCESS;
                                }
                                /// @dev Self-destructs this contract. Only callable by this contract.
                                /// @param ethRecipient Who to transfer outstanding ETH to.
                                function die(address payable ethRecipient) public virtual {
                                    require(msg.sender == _implementation, "InitialMigration/INVALID_SENDER");
                                    selfdestruct(ethRecipient);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
                            import "../errors/LibTransformERC20RichErrors.sol";
                            import "./Transformer.sol";
                            import "./LibERC20Transformer.sol";
                            /// @dev A transformer that transfers tokens to arbitrary addresses.
                            contract AffiliateFeeTransformer is
                                Transformer
                            {
                                // solhint-disable no-empty-blocks
                                using LibRichErrorsV06 for bytes;
                                using LibSafeMathV06 for uint256;
                                using LibERC20Transformer for IERC20TokenV06;
                                /// @dev Information for a single fee.
                                struct TokenFee {
                                    // The token to transfer to `recipient`.
                                    IERC20TokenV06 token;
                                    // Amount of each `token` to transfer to `recipient`.
                                    // If `amount == uint256(-1)`, the entire balance of `token` will be
                                    // transferred.
                                    uint256 amount;
                                    // Recipient of `token`.
                                    address payable recipient;
                                }
                                uint256 private constant MAX_UINT256 = uint256(-1);
                                /// @dev Create this contract.
                                constructor()
                                    public
                                    Transformer()
                                {}
                                /// @dev Transfers tokens to recipients.
                                /// @param data ABI-encoded `TokenFee[]`, indicating which tokens to transfer.
                                /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
                                function transform(
                                    bytes32, // callDataHash,
                                    address payable, // taker,
                                    bytes calldata data
                                )
                                    external
                                    override
                                    returns (bytes4 success)
                                {
                                    TokenFee[] memory fees = abi.decode(data, (TokenFee[]));
                                    // Transfer tokens to recipients.
                                    for (uint256 i = 0; i < fees.length; ++i) {
                                        uint256 amount = fees[i].amount;
                                        if (amount == MAX_UINT256) {
                                            amount = LibERC20Transformer.getTokenBalanceOf(fees[i].token, address(this));
                                        }
                                        if (amount != 0) {
                                            fees[i].token.transformerTransfer(fees[i].recipient, amount);
                                        }
                                    }
                                    return LibERC20Transformer.TRANSFORMER_SUCCESS;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "../errors/LibTransformERC20RichErrors.sol";
                            import "./IERC20Transformer.sol";
                            /// @dev Abstract base class for transformers.
                            abstract contract Transformer is
                                IERC20Transformer
                            {
                                using LibRichErrorsV06 for bytes;
                                /// @dev The address of the deployer.
                                address public immutable deployer;
                                /// @dev The original address of this contract.
                                address private immutable _implementation;
                                /// @dev Create this contract.
                                constructor() public {
                                    deployer = msg.sender;
                                    _implementation = address(this);
                                }
                                /// @dev Destruct this contract. Only callable by the deployer and will not
                                ///      succeed in the context of a delegatecall (from another contract).
                                /// @param ethRecipient The recipient of ETH held in this contract.
                                function die(address payable ethRecipient)
                                    external
                                    virtual
                                {
                                    // Only the deployer can call this.
                                    if (msg.sender != deployer) {
                                        LibTransformERC20RichErrors
                                            .OnlyCallableByDeployerError(msg.sender, deployer)
                                            .rrevert();
                                    }
                                    // Must be executing our own context.
                                    if (address(this) != _implementation) {
                                        LibTransformERC20RichErrors
                                            .InvalidExecutionContextError(address(this), _implementation)
                                            .rrevert();
                                    }
                                    selfdestruct(ethRecipient);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibMathV06.sol";
                            import "../errors/LibTransformERC20RichErrors.sol";
                            import "../vendor/v3/IExchange.sol";
                            import "./Transformer.sol";
                            import "./LibERC20Transformer.sol";
                            /// @dev A transformer that fills an ERC20 market sell/buy quote.
                            contract FillQuoteTransformer is
                                Transformer
                            {
                                using LibERC20TokenV06 for IERC20TokenV06;
                                using LibERC20Transformer for IERC20TokenV06;
                                using LibSafeMathV06 for uint256;
                                using LibRichErrorsV06 for bytes;
                                /// @dev Whether we are performing a market sell or buy.
                                enum Side {
                                    Sell,
                                    Buy
                                }
                                /// @dev Transform data to ABI-encode and pass into `transform()`.
                                struct TransformData {
                                    // Whether we aer performing a market sell or buy.
                                    Side side;
                                    // The token being sold.
                                    // This should be an actual token, not the ETH pseudo-token.
                                    IERC20TokenV06 sellToken;
                                    // The token being bought.
                                    // This should be an actual token, not the ETH pseudo-token.
                                    IERC20TokenV06 buyToken;
                                    // The orders to fill.
                                    IExchange.Order[] orders;
                                    // Signatures for each respective order in `orders`.
                                    bytes[] signatures;
                                    // Maximum fill amount for each order. This may be shorter than the
                                    // number of orders, where missing entries will be treated as `uint256(-1)`.
                                    // For sells, this will be the maximum sell amount (taker asset).
                                    // For buys, this will be the maximum buy amount (maker asset).
                                    uint256[] maxOrderFillAmounts;
                                    // Amount of `sellToken` to sell or `buyToken` to buy.
                                    // For sells, this may be `uint256(-1)` to sell the entire balance of
                                    // `sellToken`.
                                    uint256 fillAmount;
                                }
                                /// @dev Results of a call to `_fillOrder()`.
                                struct FillOrderResults {
                                    // The amount of taker tokens sold, according to balance checks.
                                    uint256 takerTokenSoldAmount;
                                    // The amount of maker tokens sold, according to balance checks.
                                    uint256 makerTokenBoughtAmount;
                                    // The amount of protocol fee paid.
                                    uint256 protocolFeePaid;
                                }
                                /// @dev The Exchange ERC20Proxy ID.
                                bytes4 private constant ERC20_ASSET_PROXY_ID = 0xf47261b0;
                                /// @dev Maximum uint256 value.
                                uint256 private constant MAX_UINT256 = uint256(-1);
                                /// @dev The Exchange contract.
                                IExchange public immutable exchange;
                                /// @dev The ERC20Proxy address.
                                address public immutable erc20Proxy;
                                /// @dev Create this contract.
                                /// @param exchange_ The Exchange V3 instance.
                                constructor(IExchange exchange_)
                                    public
                                    Transformer()
                                {
                                    exchange = exchange_;
                                    erc20Proxy = exchange_.getAssetProxy(ERC20_ASSET_PROXY_ID);
                                }
                                /// @dev Sell this contract's entire balance of of `sellToken` in exchange
                                ///      for `buyToken` by filling `orders`. Protocol fees should be attached
                                ///      to this call. `buyToken` and excess ETH will be transferred back to the caller.
                                /// @param data_ ABI-encoded `TransformData`.
                                /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
                                function transform(
                                    bytes32, // callDataHash,
                                    address payable, // taker,
                                    bytes calldata data_
                                )
                                    external
                                    override
                                    returns (bytes4 success)
                                {
                                    TransformData memory data = abi.decode(data_, (TransformData));
                                    // Validate data fields.
                                    if (data.sellToken.isTokenETH() || data.buyToken.isTokenETH()) {
                                        LibTransformERC20RichErrors.InvalidTransformDataError(
                                            LibTransformERC20RichErrors.InvalidTransformDataErrorCode.INVALID_TOKENS,
                                            data_
                                        ).rrevert();
                                    }
                                    if (data.orders.length != data.signatures.length) {
                                        LibTransformERC20RichErrors.InvalidTransformDataError(
                                            LibTransformERC20RichErrors.InvalidTransformDataErrorCode.INVALID_ARRAY_LENGTH,
                                            data_
                                        ).rrevert();
                                    }
                                    if (data.side == Side.Sell && data.fillAmount == MAX_UINT256) {
                                        // If `sellAmount == -1 then we are selling
                                        // the entire balance of `sellToken`. This is useful in cases where
                                        // the exact sell amount is not exactly known in advance, like when
                                        // unwrapping Chai/cUSDC/cDAI.
                                        data.fillAmount = data.sellToken.getTokenBalanceOf(address(this));
                                    }
                                    // Approve the ERC20 proxy to spend `sellToken`.
                                    data.sellToken.approveIfBelow(erc20Proxy, data.fillAmount);
                                    // Fill the orders.
                                    uint256 singleProtocolFee = exchange.protocolFeeMultiplier().safeMul(tx.gasprice);
                                    uint256 ethRemaining = address(this).balance;
                                    uint256 boughtAmount = 0;
                                    uint256 soldAmount = 0;
                                    for (uint256 i = 0; i < data.orders.length; ++i) {
                                        // Check if we've hit our targets.
                                        if (data.side == Side.Sell) {
                                            // Market sell check.
                                            if (soldAmount >= data.fillAmount) {
                                                break;
                                            }
                                        } else {
                                            // Market buy check.
                                            if (boughtAmount >= data.fillAmount) {
                                                break;
                                            }
                                        }
                                        // Ensure we have enough ETH to cover the protocol fee.
                                        if (ethRemaining < singleProtocolFee) {
                                            LibTransformERC20RichErrors
                                                .InsufficientProtocolFeeError(ethRemaining, singleProtocolFee)
                                                .rrevert();
                                        }
                                        // Fill the order.
                                        FillOrderResults memory results;
                                        if (data.side == Side.Sell) {
                                            // Market sell.
                                            results = _sellToOrder(
                                                data.buyToken,
                                                data.sellToken,
                                                data.orders[i],
                                                data.signatures[i],
                                                data.fillAmount.safeSub(soldAmount).min256(
                                                    data.maxOrderFillAmounts.length > i
                                                    ? data.maxOrderFillAmounts[i]
                                                    : MAX_UINT256
                                                ),
                                                singleProtocolFee
                                            );
                                        } else {
                                            // Market buy.
                                            results = _buyFromOrder(
                                                data.buyToken,
                                                data.sellToken,
                                                data.orders[i],
                                                data.signatures[i],
                                                data.fillAmount.safeSub(boughtAmount).min256(
                                                    data.maxOrderFillAmounts.length > i
                                                    ? data.maxOrderFillAmounts[i]
                                                    : MAX_UINT256
                                                ),
                                                singleProtocolFee
                                            );
                                        }
                                        // Accumulate totals.
                                        soldAmount = soldAmount.safeAdd(results.takerTokenSoldAmount);
                                        boughtAmount = boughtAmount.safeAdd(results.makerTokenBoughtAmount);
                                        ethRemaining = ethRemaining.safeSub(results.protocolFeePaid);
                                    }
                                    // Ensure we hit our targets.
                                    if (data.side == Side.Sell) {
                                        // Market sell check.
                                        if (soldAmount < data.fillAmount) {
                                            LibTransformERC20RichErrors
                                                .IncompleteFillSellQuoteError(
                                                    address(data.sellToken),
                                                    soldAmount,
                                                    data.fillAmount
                                                ).rrevert();
                                        }
                                    } else {
                                        // Market buy check.
                                        if (boughtAmount < data.fillAmount) {
                                            LibTransformERC20RichErrors
                                                .IncompleteFillBuyQuoteError(
                                                    address(data.buyToken),
                                                    boughtAmount,
                                                    data.fillAmount
                                                ).rrevert();
                                        }
                                    }
                                    return LibERC20Transformer.TRANSFORMER_SUCCESS;
                                }
                                /// @dev Try to sell up to `sellAmount` from an order.
                                /// @param makerToken The maker/buy token.
                                /// @param takerToken The taker/sell token.
                                /// @param order The order to fill.
                                /// @param signature The signature for `order`.
                                /// @param sellAmount Amount of taker token to sell.
                                /// @param protocolFee The protocol fee needed to fill `order`.
                                function _sellToOrder(
                                    IERC20TokenV06 makerToken,
                                    IERC20TokenV06 takerToken,
                                    IExchange.Order memory order,
                                    bytes memory signature,
                                    uint256 sellAmount,
                                    uint256 protocolFee
                                )
                                    private
                                    returns (FillOrderResults memory results)
                                {
                                    IERC20TokenV06 takerFeeToken =
                                        _getTokenFromERC20AssetData(order.takerFeeAssetData);
                                    uint256 takerTokenFillAmount = sellAmount;
                                    if (order.takerFee != 0) {
                                        if (takerFeeToken == makerToken) {
                                            // Taker fee is payable in the maker token, so we need to
                                            // approve the proxy to spend the maker token.
                                            // It isn't worth computing the actual taker fee
                                            // since `approveIfBelow()` will set the allowance to infinite. We
                                            // just need a reasonable upper bound to avoid unnecessarily re-approving.
                                            takerFeeToken.approveIfBelow(erc20Proxy, order.takerFee);
                                        } else if (takerFeeToken == takerToken){
                                            // Taker fee is payable in the taker token, so we need to
                                            // reduce the fill amount to cover the fee.
                                            // takerTokenFillAmount' =
                                            //   (takerTokenFillAmount * order.takerAssetAmount) /
                                            //   (order.takerAssetAmount + order.takerFee)
                                            takerTokenFillAmount = LibMathV06.getPartialAmountCeil(
                                                order.takerAssetAmount,
                                                order.takerAssetAmount.safeAdd(order.takerFee),
                                                sellAmount
                                            );
                                        } else {
                                            //  Only support taker or maker asset denominated taker fees.
                                            LibTransformERC20RichErrors.InvalidTakerFeeTokenError(
                                                address(takerFeeToken)
                                            ).rrevert();
                                        }
                                    }
                                    // Clamp fill amount to order size.
                                    takerTokenFillAmount = LibSafeMathV06.min256(
                                        takerTokenFillAmount,
                                        order.takerAssetAmount
                                    );
                                    // Perform the fill.
                                    return _fillOrder(
                                        order,
                                        signature,
                                        takerTokenFillAmount,
                                        protocolFee,
                                        makerToken,
                                        takerFeeToken == takerToken
                                    );
                                }
                                /// @dev Try to buy up to `buyAmount` from an order.
                                /// @param makerToken The maker/buy token.
                                /// @param takerToken The taker/sell token.
                                /// @param order The order to fill.
                                /// @param signature The signature for `order`.
                                /// @param buyAmount Amount of maker token to buy.
                                /// @param protocolFee The protocol fee needed to fill `order`.
                                function _buyFromOrder(
                                    IERC20TokenV06 makerToken,
                                    IERC20TokenV06 takerToken,
                                    IExchange.Order memory order,
                                    bytes memory signature,
                                    uint256 buyAmount,
                                    uint256 protocolFee
                                )
                                    private
                                    returns (FillOrderResults memory results)
                                {
                                    IERC20TokenV06 takerFeeToken =
                                        _getTokenFromERC20AssetData(order.takerFeeAssetData);
                                    // Compute the default taker token fill amount.
                                    uint256 takerTokenFillAmount = LibMathV06.getPartialAmountCeil(
                                        buyAmount,
                                        order.makerAssetAmount,
                                        order.takerAssetAmount
                                    );
                                    if (order.takerFee != 0) {
                                        if (takerFeeToken == makerToken) {
                                            // Taker fee is payable in the maker token.
                                            // Adjust the taker token fill amount to account for maker
                                            // tokens being lost to the taker fee.
                                            // takerTokenFillAmount' =
                                            //  (order.takerAssetAmount * buyAmount) /
                                            //  (order.makerAssetAmount - order.takerFee)
                                            takerTokenFillAmount = LibMathV06.getPartialAmountCeil(
                                                buyAmount,
                                                order.makerAssetAmount.safeSub(order.takerFee),
                                                order.takerAssetAmount
                                            );
                                            // Approve the proxy to spend the maker token.
                                            // It isn't worth computing the actual taker fee
                                            // since `approveIfBelow()` will set the allowance to infinite. We
                                            // just need a reasonable upper bound to avoid unnecessarily re-approving.
                                            takerFeeToken.approveIfBelow(erc20Proxy, order.takerFee);
                                        } else if (takerFeeToken != takerToken) {
                                            //  Only support taker or maker asset denominated taker fees.
                                            LibTransformERC20RichErrors.InvalidTakerFeeTokenError(
                                                address(takerFeeToken)
                                            ).rrevert();
                                        }
                                    }
                                    // Clamp to order size.
                                    takerTokenFillAmount = LibSafeMathV06.min256(
                                        order.takerAssetAmount,
                                        takerTokenFillAmount
                                    );
                                    // Perform the fill.
                                    return _fillOrder(
                                        order,
                                        signature,
                                        takerTokenFillAmount,
                                        protocolFee,
                                        makerToken,
                                        takerFeeToken == takerToken
                                    );
                                }
                                /// @dev Attempt to fill an order. If the fill reverts, the revert will be
                                ///      swallowed and `results` will be zeroed out.
                                /// @param order The order to fill.
                                /// @param signature The order signature.
                                /// @param takerAssetFillAmount How much taker asset to fill.
                                /// @param protocolFee The protocol fee needed to fill this order.
                                /// @param makerToken The maker token.
                                /// @param isTakerFeeInTakerToken Whether the taker fee token is the same as the
                                ///        taker token.
                                function _fillOrder(
                                    IExchange.Order memory order,
                                    bytes memory signature,
                                    uint256 takerAssetFillAmount,
                                    uint256 protocolFee,
                                    IERC20TokenV06 makerToken,
                                    bool isTakerFeeInTakerToken
                                )
                                    private
                                    returns (FillOrderResults memory results)
                                {
                                    // Track changes in the maker token balance.
                                    uint256 initialMakerTokenBalance = makerToken.balanceOf(address(this));
                                    try
                                        exchange.fillOrder
                                            {value: protocolFee}
                                            (order, takerAssetFillAmount, signature)
                                        returns (IExchange.FillResults memory fillResults)
                                    {
                                        // Update maker quantity based on changes in token balances.
                                        results.makerTokenBoughtAmount = makerToken.balanceOf(address(this))
                                            .safeSub(initialMakerTokenBalance);
                                        // We can trust the other fill result quantities.
                                        results.protocolFeePaid = fillResults.protocolFeePaid;
                                        results.takerTokenSoldAmount = fillResults.takerAssetFilledAmount;
                                        // If the taker fee is payable in the taker asset, include the
                                        // taker fee in the total amount sold.
                                        if (isTakerFeeInTakerToken) {
                                            results.takerTokenSoldAmount =
                                                results.takerTokenSoldAmount.safeAdd(fillResults.takerFeePaid);
                                        }
                                    } catch (bytes memory) {
                                        // Swallow failures, leaving all results as zero.
                                    }
                                }
                                /// @dev Extract the token from plain ERC20 asset data.
                                ///      If the asset-data is empty, a zero token address will be returned.
                                /// @param assetData The order asset data.
                                function _getTokenFromERC20AssetData(bytes memory assetData)
                                    private
                                    pure
                                    returns (IERC20TokenV06 token)
                                {
                                    if (assetData.length == 0) {
                                        return IERC20TokenV06(address(0));
                                    }
                                    if (assetData.length != 36 ||
                                        LibBytesV06.readBytes4(assetData, 0) != ERC20_ASSET_PROXY_ID)
                                    {
                                        LibTransformERC20RichErrors
                                            .InvalidERC20AssetDataError(assetData)
                                            .rrevert();
                                    }
                                    return IERC20TokenV06(LibBytesV06.readAddress(assetData, 16));
                                }
                            }
                            /*
                              Copyright 2019 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./LibSafeMathV06.sol";
                            import "./errors/LibRichErrorsV06.sol";
                            import "./errors/LibMathRichErrorsV06.sol";
                            library LibMathV06 {
                                using LibSafeMathV06 for uint256;
                                /// @dev Calculates partial value given a numerator and denominator rounded down.
                                ///      Reverts if rounding error is >= 0.1%
                                /// @param numerator Numerator.
                                /// @param denominator Denominator.
                                /// @param target Value to calculate partial of.
                                /// @return partialAmount Partial value of target rounded down.
                                function safeGetPartialAmountFloor(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                )
                                    internal
                                    pure
                                    returns (uint256 partialAmount)
                                {
                                    if (isRoundingErrorFloor(
                                            numerator,
                                            denominator,
                                            target
                                    )) {
                                        LibRichErrorsV06.rrevert(LibMathRichErrorsV06.RoundingError(
                                            numerator,
                                            denominator,
                                            target
                                        ));
                                    }
                                    partialAmount = numerator.safeMul(target).safeDiv(denominator);
                                    return partialAmount;
                                }
                                /// @dev Calculates partial value given a numerator and denominator rounded down.
                                ///      Reverts if rounding error is >= 0.1%
                                /// @param numerator Numerator.
                                /// @param denominator Denominator.
                                /// @param target Value to calculate partial of.
                                /// @return partialAmount Partial value of target rounded up.
                                function safeGetPartialAmountCeil(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                )
                                    internal
                                    pure
                                    returns (uint256 partialAmount)
                                {
                                    if (isRoundingErrorCeil(
                                            numerator,
                                            denominator,
                                            target
                                    )) {
                                        LibRichErrorsV06.rrevert(LibMathRichErrorsV06.RoundingError(
                                            numerator,
                                            denominator,
                                            target
                                        ));
                                    }
                                    // safeDiv computes `floor(a / b)`. We use the identity (a, b integer):
                                    //       ceil(a / b) = floor((a + b - 1) / b)
                                    // To implement `ceil(a / b)` using safeDiv.
                                    partialAmount = numerator.safeMul(target)
                                        .safeAdd(denominator.safeSub(1))
                                        .safeDiv(denominator);
                                    return partialAmount;
                                }
                                /// @dev Calculates partial value given a numerator and denominator rounded down.
                                /// @param numerator Numerator.
                                /// @param denominator Denominator.
                                /// @param target Value to calculate partial of.
                                /// @return partialAmount Partial value of target rounded down.
                                function getPartialAmountFloor(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                )
                                    internal
                                    pure
                                    returns (uint256 partialAmount)
                                {
                                    partialAmount = numerator.safeMul(target).safeDiv(denominator);
                                    return partialAmount;
                                }
                                /// @dev Calculates partial value given a numerator and denominator rounded down.
                                /// @param numerator Numerator.
                                /// @param denominator Denominator.
                                /// @param target Value to calculate partial of.
                                /// @return partialAmount Partial value of target rounded up.
                                function getPartialAmountCeil(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                )
                                    internal
                                    pure
                                    returns (uint256 partialAmount)
                                {
                                    // safeDiv computes `floor(a / b)`. We use the identity (a, b integer):
                                    //       ceil(a / b) = floor((a + b - 1) / b)
                                    // To implement `ceil(a / b)` using safeDiv.
                                    partialAmount = numerator.safeMul(target)
                                        .safeAdd(denominator.safeSub(1))
                                        .safeDiv(denominator);
                                    return partialAmount;
                                }
                                /// @dev Checks if rounding error >= 0.1% when rounding down.
                                /// @param numerator Numerator.
                                /// @param denominator Denominator.
                                /// @param target Value to multiply with numerator/denominator.
                                /// @return isError Rounding error is present.
                                function isRoundingErrorFloor(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                )
                                    internal
                                    pure
                                    returns (bool isError)
                                {
                                    if (denominator == 0) {
                                        LibRichErrorsV06.rrevert(LibMathRichErrorsV06.DivisionByZeroError());
                                    }
                                    // The absolute rounding error is the difference between the rounded
                                    // value and the ideal value. The relative rounding error is the
                                    // absolute rounding error divided by the absolute value of the
                                    // ideal value. This is undefined when the ideal value is zero.
                                    //
                                    // The ideal value is `numerator * target / denominator`.
                                    // Let's call `numerator * target % denominator` the remainder.
                                    // The absolute error is `remainder / denominator`.
                                    //
                                    // When the ideal value is zero, we require the absolute error to
                                    // be zero. Fortunately, this is always the case. The ideal value is
                                    // zero iff `numerator == 0` and/or `target == 0`. In this case the
                                    // remainder and absolute error are also zero.
                                    if (target == 0 || numerator == 0) {
                                        return false;
                                    }
                                    // Otherwise, we want the relative rounding error to be strictly
                                    // less than 0.1%.
                                    // The relative error is `remainder / (numerator * target)`.
                                    // We want the relative error less than 1 / 1000:
                                    //        remainder / (numerator * denominator)  <  1 / 1000
                                    // or equivalently:
                                    //        1000 * remainder  <  numerator * target
                                    // so we have a rounding error iff:
                                    //        1000 * remainder  >=  numerator * target
                                    uint256 remainder = mulmod(
                                        target,
                                        numerator,
                                        denominator
                                    );
                                    isError = remainder.safeMul(1000) >= numerator.safeMul(target);
                                    return isError;
                                }
                                /// @dev Checks if rounding error >= 0.1% when rounding up.
                                /// @param numerator Numerator.
                                /// @param denominator Denominator.
                                /// @param target Value to multiply with numerator/denominator.
                                /// @return isError Rounding error is present.
                                function isRoundingErrorCeil(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                )
                                    internal
                                    pure
                                    returns (bool isError)
                                {
                                    if (denominator == 0) {
                                        LibRichErrorsV06.rrevert(LibMathRichErrorsV06.DivisionByZeroError());
                                    }
                                    // See the comments in `isRoundingError`.
                                    if (target == 0 || numerator == 0) {
                                        // When either is zero, the ideal value and rounded value are zero
                                        // and there is no rounding error. (Although the relative error
                                        // is undefined.)
                                        return false;
                                    }
                                    // Compute remainder as before
                                    uint256 remainder = mulmod(
                                        target,
                                        numerator,
                                        denominator
                                    );
                                    remainder = denominator.safeSub(remainder) % denominator;
                                    isError = remainder.safeMul(1000) >= numerator.safeMul(target);
                                    return isError;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibMathRichErrorsV06 {
                                // bytes4(keccak256("DivisionByZeroError()"))
                                bytes internal constant DIVISION_BY_ZERO_ERROR =
                                    hex"a791837c";
                                // bytes4(keccak256("RoundingError(uint256,uint256,uint256)"))
                                bytes4 internal constant ROUNDING_ERROR_SELECTOR =
                                    0x339f3de2;
                                // solhint-disable func-name-mixedcase
                                function DivisionByZeroError()
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return DIVISION_BY_ZERO_ERROR;
                                }
                                function RoundingError(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        ROUNDING_ERROR_SELECTOR,
                                        numerator,
                                        denominator,
                                        target
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            /// @dev Interface to the V3 Exchange.
                            interface IExchange {
                                /// @dev V3 Order structure.
                                struct Order {
                                    // Address that created the order.
                                    address makerAddress;
                                    // Address that is allowed to fill the order.
                                    // If set to 0, any address is allowed to fill the order.
                                    address takerAddress;
                                    // Address that will recieve fees when order is filled.
                                    address feeRecipientAddress;
                                    // Address that is allowed to call Exchange contract methods that affect this order.
                                    // If set to 0, any address is allowed to call these methods.
                                    address senderAddress;
                                    // Amount of makerAsset being offered by maker. Must be greater than 0.
                                    uint256 makerAssetAmount;
                                    // Amount of takerAsset being bid on by maker. Must be greater than 0.
                                    uint256 takerAssetAmount;
                                    // Fee paid to feeRecipient by maker when order is filled.
                                    uint256 makerFee;
                                    // Fee paid to feeRecipient by taker when order is filled.
                                    uint256 takerFee;
                                    // Timestamp in seconds at which order expires.
                                    uint256 expirationTimeSeconds;
                                    // Arbitrary number to facilitate uniqueness of the order's hash.
                                    uint256 salt;
                                    // Encoded data that can be decoded by a specified proxy contract when transferring makerAsset.
                                    // The leading bytes4 references the id of the asset proxy.
                                    bytes makerAssetData;
                                    // Encoded data that can be decoded by a specified proxy contract when transferring takerAsset.
                                    // The leading bytes4 references the id of the asset proxy.
                                    bytes takerAssetData;
                                    // Encoded data that can be decoded by a specified proxy contract when transferring makerFeeAsset.
                                    // The leading bytes4 references the id of the asset proxy.
                                    bytes makerFeeAssetData;
                                    // Encoded data that can be decoded by a specified proxy contract when transferring takerFeeAsset.
                                    // The leading bytes4 references the id of the asset proxy.
                                    bytes takerFeeAssetData;
                                }
                                /// @dev V3 `fillOrder()` results.`
                                struct FillResults {
                                    // Total amount of makerAsset(s) filled.
                                    uint256 makerAssetFilledAmount;
                                    // Total amount of takerAsset(s) filled.
                                    uint256 takerAssetFilledAmount;
                                    // Total amount of fees paid by maker(s) to feeRecipient(s).
                                    uint256 makerFeePaid;
                                    // Total amount of fees paid by taker to feeRecipients(s).
                                    uint256 takerFeePaid;
                                    // Total amount of fees paid by taker to the staking contract.
                                    uint256 protocolFeePaid;
                                }
                                /// @dev Fills the input order.
                                /// @param order Order struct containing order specifications.
                                /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
                                /// @param signature Proof that order has been created by maker.
                                /// @return fillResults Amounts filled and fees paid by maker and taker.
                                function fillOrder(
                                    Order calldata order,
                                    uint256 takerAssetFillAmount,
                                    bytes calldata signature
                                )
                                    external
                                    payable
                                    returns (FillResults memory fillResults);
                                /// @dev Returns the protocolFeeMultiplier
                                /// @return multiplier The multiplier for protocol fees.
                                function protocolFeeMultiplier()
                                    external
                                    view
                                    returns (uint256 multiplier);
                                /// @dev Gets an asset proxy.
                                /// @param assetProxyId Id of the asset proxy.
                                /// @return proxyAddress The asset proxy registered to assetProxyId.
                                ///         Returns 0x0 if no proxy is registered.
                                function getAssetProxy(bytes4 assetProxyId)
                                    external
                                    view
                                    returns (address proxyAddress);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
                            import "../errors/LibTransformERC20RichErrors.sol";
                            import "./Transformer.sol";
                            import "./LibERC20Transformer.sol";
                            /// @dev A transformer that transfers tokens to the taker.
                            contract PayTakerTransformer is
                                Transformer
                            {
                                // solhint-disable no-empty-blocks
                                using LibRichErrorsV06 for bytes;
                                using LibSafeMathV06 for uint256;
                                using LibERC20Transformer for IERC20TokenV06;
                                /// @dev Transform data to ABI-encode and pass into `transform()`.
                                struct TransformData {
                                    // The tokens to transfer to the taker.
                                    IERC20TokenV06[] tokens;
                                    // Amount of each token in `tokens` to transfer to the taker.
                                    // `uint(-1)` will transfer the entire balance.
                                    uint256[] amounts;
                                }
                                /// @dev Maximum uint256 value.
                                uint256 private constant MAX_UINT256 = uint256(-1);
                                /// @dev Create this contract.
                                constructor()
                                    public
                                    Transformer()
                                {}
                                /// @dev Forwards tokens to the taker.
                                /// @param taker The taker address (caller of `TransformERC20.transformERC20()`).
                                /// @param data_ ABI-encoded `TransformData`, indicating which tokens to transfer.
                                /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
                                function transform(
                                    bytes32, // callDataHash,
                                    address payable taker,
                                    bytes calldata data_
                                )
                                    external
                                    override
                                    returns (bytes4 success)
                                {
                                    TransformData memory data = abi.decode(data_, (TransformData));
                                    // Transfer tokens directly to the taker.
                                    for (uint256 i = 0; i < data.tokens.length; ++i) {
                                        // The `amounts` array can be shorter than the `tokens` array.
                                        // Missing elements are treated as `uint256(-1)`.
                                        uint256 amount = data.amounts.length > i ? data.amounts[i] : uint256(-1);
                                        if (amount == MAX_UINT256) {
                                            amount = data.tokens[i].getTokenBalanceOf(address(this));
                                        }
                                        if (amount != 0) {
                                            data.tokens[i].transformerTransfer(taker, amount);
                                        }
                                    }
                                    return LibERC20Transformer.TRANSFORMER_SUCCESS;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/IEtherTokenV06.sol";
                            import "../errors/LibTransformERC20RichErrors.sol";
                            import "./Transformer.sol";
                            import "./LibERC20Transformer.sol";
                            /// @dev A transformer that wraps or unwraps WETH.
                            contract WethTransformer is
                                Transformer
                            {
                                using LibRichErrorsV06 for bytes;
                                using LibSafeMathV06 for uint256;
                                using LibERC20Transformer for IERC20TokenV06;
                                /// @dev Transform data to ABI-encode and pass into `transform()`.
                                struct TransformData {
                                    // The token to wrap/unwrap. Must be either ETH or WETH.
                                    IERC20TokenV06 token;
                                    // Amount of `token` to wrap or unwrap.
                                    // `uint(-1)` will unwrap the entire balance.
                                    uint256 amount;
                                }
                                /// @dev The WETH contract address.
                                IEtherTokenV06 public immutable weth;
                                /// @dev Maximum uint256 value.
                                uint256 private constant MAX_UINT256 = uint256(-1);
                                /// @dev Construct the transformer and store the WETH address in an immutable.
                                /// @param weth_ The weth token.
                                constructor(IEtherTokenV06 weth_)
                                    public
                                    Transformer()
                                {
                                    weth = weth_;
                                }
                                /// @dev Wraps and unwraps WETH.
                                /// @param data_ ABI-encoded `TransformData`, indicating which token to wrap/umwrap.
                                /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
                                function transform(
                                    bytes32, // callDataHash,
                                    address payable, // taker,
                                    bytes calldata data_
                                )
                                    external
                                    override
                                    returns (bytes4 success)
                                {
                                    TransformData memory data = abi.decode(data_, (TransformData));
                                    if (!data.token.isTokenETH() && data.token != weth) {
                                        LibTransformERC20RichErrors.InvalidTransformDataError(
                                            LibTransformERC20RichErrors.InvalidTransformDataErrorCode.INVALID_TOKENS,
                                            data_
                                        ).rrevert();
                                    }
                                    uint256 amount = data.amount;
                                    if (amount == MAX_UINT256) {
                                        amount = data.token.getTokenBalanceOf(address(this));
                                    }
                                    if (amount != 0) {
                                        if (data.token.isTokenETH()) {
                                            // Wrap ETH.
                                            weth.deposit{value: amount}();
                                        } else {
                                            // Unwrap WETH.
                                            weth.withdraw(amount);
                                        }
                                    }
                                    return LibERC20Transformer.TRANSFORMER_SUCCESS;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./IERC20TokenV06.sol";
                            interface IEtherTokenV06 is
                                IERC20TokenV06
                            {
                                /// @dev Wrap ether.
                                function deposit() external payable;
                                /// @dev Unwrap ether.
                                function withdraw(uint256 amount) external;
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            interface ITestSimpleFunctionRegistryFeature {
                                function testFn() external view returns (uint256 id);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            contract TestCallTarget {
                                event CallTargetCalled(
                                    address context,
                                    address sender,
                                    bytes data,
                                    uint256 value
                                );
                                bytes4 private constant MAGIC_BYTES = 0x12345678;
                                bytes private constant REVERTING_DATA = hex"1337";
                                fallback() external payable {
                                    if (keccak256(msg.data) == keccak256(REVERTING_DATA)) {
                                        revert("TestCallTarget/REVERT");
                                    }
                                    emit CallTargetCalled(
                                        address(this),
                                        msg.sender,
                                        msg.data,
                                        msg.value
                                    );
                                    bytes4 rval = MAGIC_BYTES;
                                    assembly {
                                        mstore(0, rval)
                                        return(0, 32)
                                    }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            contract TestDelegateCaller {
                                function executeDelegateCall(
                                    address target,
                                    bytes calldata callData
                                )
                                    external
                                {
                                    (bool success, bytes memory resultData) = target.delegatecall(callData);
                                    if (!success) {
                                        assembly { revert(add(resultData, 32), mload(resultData)) }
                                    }
                                    assembly { return(add(resultData, 32), mload(resultData)) }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibMathV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            import "../src/vendor/v3/IExchange.sol";
                            import "./TestMintableERC20Token.sol";
                            contract TestFillQuoteTransformerExchange {
                                struct FillBehavior {
                                    // How much of the order is filled, in taker asset amount.
                                    uint256 filledTakerAssetAmount;
                                    // Scaling for maker assets minted, in 1e18.
                                    uint256 makerAssetMintRatio;
                                }
                                uint256 private constant PROTOCOL_FEE_MULTIPLIER = 1337;
                                using LibSafeMathV06 for uint256;
                                function fillOrder(
                                    IExchange.Order calldata order,
                                    uint256 takerAssetFillAmount,
                                    bytes calldata signature
                                )
                                    external
                                    payable
                                    returns (IExchange.FillResults memory fillResults)
                                {
                                    require(
                                        signature.length != 0,
                                        "TestFillQuoteTransformerExchange/INVALID_SIGNATURE"
                                    );
                                    // The signature is the ABI-encoded FillBehavior data.
                                    FillBehavior memory behavior = abi.decode(signature, (FillBehavior));
                                    uint256 protocolFee = PROTOCOL_FEE_MULTIPLIER * tx.gasprice;
                                    require(
                                        msg.value == protocolFee,
                                        "TestFillQuoteTransformerExchange/INSUFFICIENT_PROTOCOL_FEE"
                                    );
                                    // Return excess protocol fee.
                                    msg.sender.transfer(msg.value - protocolFee);
                                    // Take taker tokens.
                                    TestMintableERC20Token takerToken = _getTokenFromAssetData(order.takerAssetData);
                                    takerAssetFillAmount = LibSafeMathV06.min256(
                                        order.takerAssetAmount.safeSub(behavior.filledTakerAssetAmount),
                                        takerAssetFillAmount
                                    );
                                    require(
                                        takerToken.getSpendableAmount(msg.sender, address(this)) >= takerAssetFillAmount,
                                        "TestFillQuoteTransformerExchange/INSUFFICIENT_TAKER_FUNDS"
                                    );
                                    takerToken.transferFrom(msg.sender, order.makerAddress, takerAssetFillAmount);
                                    // Mint maker tokens.
                                    uint256 makerAssetFilledAmount = LibMathV06.getPartialAmountFloor(
                                        takerAssetFillAmount,
                                        order.takerAssetAmount,
                                        order.makerAssetAmount
                                    );
                                    TestMintableERC20Token makerToken = _getTokenFromAssetData(order.makerAssetData);
                                    makerToken.mint(
                                        msg.sender,
                                        LibMathV06.getPartialAmountFloor(
                                            behavior.makerAssetMintRatio,
                                            1e18,
                                            makerAssetFilledAmount
                                        )
                                    );
                                    // Take taker fee.
                                    TestMintableERC20Token takerFeeToken = _getTokenFromAssetData(order.takerFeeAssetData);
                                    uint256 takerFee = LibMathV06.getPartialAmountFloor(
                                        takerAssetFillAmount,
                                        order.takerAssetAmount,
                                        order.takerFee
                                    );
                                    require(
                                        takerFeeToken.getSpendableAmount(msg.sender, address(this)) >= takerFee,
                                        "TestFillQuoteTransformerExchange/INSUFFICIENT_TAKER_FEE_FUNDS"
                                    );
                                    takerFeeToken.transferFrom(msg.sender, order.feeRecipientAddress, takerFee);
                                    fillResults.makerAssetFilledAmount = makerAssetFilledAmount;
                                    fillResults.takerAssetFilledAmount = takerAssetFillAmount;
                                    fillResults.makerFeePaid = uint256(-1);
                                    fillResults.takerFeePaid = takerFee;
                                    fillResults.protocolFeePaid = protocolFee;
                                }
                                function encodeBehaviorData(FillBehavior calldata behavior)
                                    external
                                    pure
                                    returns (bytes memory encoded)
                                {
                                    return abi.encode(behavior);
                                }
                                function protocolFeeMultiplier()
                                    external
                                    pure
                                    returns (uint256)
                                {
                                    return PROTOCOL_FEE_MULTIPLIER;
                                }
                                function getAssetProxy(bytes4)
                                    external
                                    view
                                    returns (address)
                                {
                                    return address(this);
                                }
                                function _getTokenFromAssetData(bytes memory assetData)
                                    private
                                    pure
                                    returns (TestMintableERC20Token token)
                                {
                                    return TestMintableERC20Token(LibBytesV06.readAddress(assetData, 16));
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            contract TestMintableERC20Token {
                                mapping(address => uint256) public balanceOf;
                                mapping(address => mapping(address => uint256)) public allowance;
                                function transfer(address to, uint256 amount)
                                    external
                                    virtual
                                    returns (bool)
                                {
                                    return transferFrom(msg.sender, to, amount);
                                }
                                function approve(address spender, uint256 amount)
                                    external
                                    virtual
                                    returns (bool)
                                {
                                    allowance[msg.sender][spender] = amount;
                                    return true;
                                }
                                function mint(address owner, uint256 amount)
                                    external
                                    virtual
                                {
                                    balanceOf[owner] += amount;
                                }
                                function burn(address owner, uint256 amount)
                                    external
                                    virtual
                                {
                                    require(balanceOf[owner] >= amount, "TestMintableERC20Token/INSUFFICIENT_FUNDS");
                                    balanceOf[owner] -= amount;
                                }
                                function transferFrom(address from, address to, uint256 amount)
                                    public
                                    virtual
                                    returns (bool)
                                {
                                    if (from != msg.sender) {
                                        require(
                                            allowance[from][msg.sender] >= amount,
                                            "TestMintableERC20Token/INSUFFICIENT_ALLOWANCE"
                                        );
                                        allowance[from][msg.sender] -= amount;
                                    }
                                    require(balanceOf[from] >= amount, "TestMintableERC20Token/INSUFFICIENT_FUNDS");
                                    balanceOf[from] -= amount;
                                    balanceOf[to] += amount;
                                    return true;
                                }
                                function getSpendableAmount(address owner, address spender)
                                    external
                                    view
                                    returns (uint256)
                                {
                                    return balanceOf[owner] < allowance[owner][spender]
                                        ? balanceOf[owner]
                                        : allowance[owner][spender];
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/transformers/IERC20Transformer.sol";
                            import "./TestMintableERC20Token.sol";
                            import "./TestTransformerHost.sol";
                            contract TestFillQuoteTransformerHost is
                                TestTransformerHost
                            {
                                function executeTransform(
                                    IERC20Transformer transformer,
                                    TestMintableERC20Token inputToken,
                                    uint256 inputTokenAmount,
                                    bytes calldata data
                                )
                                    external
                                    payable
                                {
                                    if (inputTokenAmount != 0) {
                                        inputToken.mint(address(this), inputTokenAmount);
                                    }
                                    // Have to make this call externally because transformers aren't payable.
                                    this.rawExecuteTransform(transformer, bytes32(0), msg.sender, data);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "../src/transformers/IERC20Transformer.sol";
                            import "../src/transformers/LibERC20Transformer.sol";
                            contract TestTransformerHost {
                                using LibERC20Transformer for IERC20TokenV06;
                                using LibRichErrorsV06 for bytes;
                                function rawExecuteTransform(
                                    IERC20Transformer transformer,
                                    bytes32 callDataHash,
                                    address taker,
                                    bytes calldata data
                                )
                                    external
                                {
                                    (bool _success, bytes memory resultData) =
                                        address(transformer).delegatecall(abi.encodeWithSelector(
                                            transformer.transform.selector,
                                            callDataHash,
                                            taker,
                                            data
                                        ));
                                    if (!_success) {
                                        resultData.rrevert();
                                    }
                                    require(
                                        abi.decode(resultData, (bytes4)) == LibERC20Transformer.TRANSFORMER_SUCCESS,
                                        "TestTransformerHost/INVALID_TRANSFORMER_RESULT"
                                    );
                                }
                                // solhint-disable
                                receive() external payable {}
                                // solhint-enable
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/ZeroEx.sol";
                            import "../src/features/IBootstrap.sol";
                            import "../src/migrations/FullMigration.sol";
                            contract TestFullMigration is
                                FullMigration
                            {
                                address public dieRecipient;
                                // solhint-disable-next-line no-empty-blocks
                                constructor(address payable deployer) public FullMigration(deployer) {}
                                function die(address payable ethRecipient) external override {
                                    dieRecipient = ethRecipient;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/ZeroEx.sol";
                            import "../src/features/IBootstrap.sol";
                            import "../src/migrations/InitialMigration.sol";
                            contract TestInitialMigration is
                                InitialMigration
                            {
                                address public bootstrapFeature;
                                address public dieRecipient;
                                // solhint-disable-next-line no-empty-blocks
                                constructor(address deployer) public InitialMigration(deployer) {}
                                function callBootstrap(ZeroEx zeroEx) external {
                                    IBootstrap(address(zeroEx)).bootstrap(address(this), new bytes(0));
                                }
                                function bootstrap(address owner, BootstrapFeatures memory features)
                                    public
                                    override
                                    returns (bytes4 success)
                                {
                                    success = InitialMigration.bootstrap(owner, features);
                                    // Snoop the bootstrap feature contract.
                                    bootstrapFeature = ZeroEx(address(uint160(address(this))))
                                        .getFunctionImplementation(IBootstrap.bootstrap.selector);
                                }
                                function die(address payable ethRecipient) public override {
                                    dieRecipient = ethRecipient;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/migrations/LibMigrate.sol";
                            import "../src/features/IOwnable.sol";
                            contract TestMigrator {
                                event TestMigrateCalled(
                                    bytes callData,
                                    address owner
                                );
                                function succeedingMigrate() external returns (bytes4 success) {
                                    emit TestMigrateCalled(
                                        msg.data,
                                        IOwnable(address(this)).owner()
                                    );
                                    return LibMigrate.MIGRATE_SUCCESS;
                                }
                                function failingMigrate() external returns (bytes4 success) {
                                    emit TestMigrateCalled(
                                        msg.data,
                                        IOwnable(address(this)).owner()
                                    );
                                    return 0xdeadbeef;
                                }
                                function revertingMigrate() external pure {
                                    revert("OOPSIE");
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "../src/transformers/IERC20Transformer.sol";
                            import "../src/transformers/LibERC20Transformer.sol";
                            import "./TestMintableERC20Token.sol";
                            contract TestMintTokenERC20Transformer is
                                IERC20Transformer
                            {
                                struct TransformData {
                                    IERC20TokenV06 inputToken;
                                    TestMintableERC20Token outputToken;
                                    uint256 burnAmount;
                                    uint256 mintAmount;
                                    uint256 feeAmount;
                                }
                                event MintTransform(
                                    address context,
                                    address caller,
                                    bytes32 callDataHash,
                                    address taker,
                                    bytes data,
                                    uint256 inputTokenBalance,
                                    uint256 ethBalance
                                );
                                function transform(
                                    bytes32 callDataHash,
                                    address payable taker,
                                    bytes calldata data_
                                )
                                    external
                                    override
                                    returns (bytes4 success)
                                {
                                    TransformData memory data = abi.decode(data_, (TransformData));
                                    emit MintTransform(
                                        address(this),
                                        msg.sender,
                                        callDataHash,
                                        taker,
                                        data_,
                                        data.inputToken.balanceOf(address(this)),
                                        address(this).balance
                                    );
                                    // "Burn" input tokens.
                                    data.inputToken.transfer(address(0), data.burnAmount);
                                    // Mint output tokens.
                                    if (LibERC20Transformer.isTokenETH(IERC20TokenV06(address(data.outputToken)))) {
                                        taker.transfer(data.mintAmount);
                                    } else {
                                        data.outputToken.mint(
                                            taker,
                                            data.mintAmount
                                        );
                                        // Burn fees from output.
                                        data.outputToken.burn(taker, data.feeAmount);
                                    }
                                    return LibERC20Transformer.TRANSFORMER_SUCCESS;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/fixins/FixinCommon.sol";
                            contract TestSimpleFunctionRegistryFeatureImpl1 is
                                FixinCommon
                            {
                                function testFn()
                                    external
                                    pure
                                    returns (uint256 id)
                                {
                                    return 1337;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/fixins/FixinCommon.sol";
                            contract TestSimpleFunctionRegistryFeatureImpl2 is
                                FixinCommon
                            {
                                function testFn()
                                    external
                                    pure
                                    returns (uint256 id)
                                {
                                    return 1338;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/features/TokenSpender.sol";
                            contract TestTokenSpender is
                                TokenSpender
                            {
                                modifier onlySelf() override {
                                    _;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "./TestMintableERC20Token.sol";
                            contract TestTokenSpenderERC20Token is
                                TestMintableERC20Token
                            {
                                event TransferFromCalled(
                                    address sender,
                                    address from,
                                    address to,
                                    uint256 amount
                                );
                                // `transferFrom()` behavior depends on the value of `amount`.
                                uint256 constant private EMPTY_RETURN_AMOUNT = 1337;
                                uint256 constant private FALSE_RETURN_AMOUNT = 1338;
                                uint256 constant private REVERT_RETURN_AMOUNT = 1339;
                                function transferFrom(address from, address to, uint256 amount)
                                    public
                                    override
                                    returns (bool)
                                {
                                    emit TransferFromCalled(msg.sender, from, to, amount);
                                    if (amount == EMPTY_RETURN_AMOUNT) {
                                        assembly { return(0, 0) }
                                    }
                                    if (amount == FALSE_RETURN_AMOUNT) {
                                        return false;
                                    }
                                    if (amount == REVERT_RETURN_AMOUNT) {
                                        revert("TestTokenSpenderERC20Token/Revert");
                                    }
                                    return true;
                                }
                                function setBalanceAndAllowanceOf(
                                    address owner,
                                    uint256 balance,
                                    address spender,
                                    uint256 allowance_
                                )
                                    external
                                {
                                    balanceOf[owner] = balance;
                                    allowance[owner][spender] = allowance_;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/features/TransformERC20.sol";
                            contract TestTransformERC20 is
                                TransformERC20
                            {
                                // solhint-disable no-empty-blocks
                                constructor()
                                    TransformERC20()
                                    public
                                {}
                                modifier onlySelf() override {
                                    _;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/transformers/Transformer.sol";
                            import "../src/transformers/LibERC20Transformer.sol";
                            contract TestTransformerBase is
                                Transformer
                            {
                                function transform(
                                    bytes32,
                                    address payable,
                                    bytes calldata
                                )
                                    external
                                    override
                                    returns (bytes4 success)
                                {
                                    return LibERC20Transformer.TRANSFORMER_SUCCESS;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/transformers/LibERC20Transformer.sol";
                            contract TestTransformerDeployerTransformer {
                                address payable public immutable deployer;
                                constructor() public payable {
                                    deployer = msg.sender;
                                }
                                modifier onlyDeployer() {
                                    require(msg.sender == deployer, "TestTransformerDeployerTransformer/ONLY_DEPLOYER");
                                    _;
                                }
                                function die()
                                    external
                                    onlyDeployer
                                {
                                    selfdestruct(deployer);
                                }
                                function isDeployedByDeployer(uint32 nonce)
                                    external
                                    view
                                    returns (bool)
                                {
                                    return LibERC20Transformer.getDeployedAddress(deployer, nonce) == address(this);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "./TestMintableERC20Token.sol";
                            contract TestWeth is
                                TestMintableERC20Token
                            {
                                function deposit()
                                    external
                                    payable
                                {
                                    this.mint(msg.sender, msg.value);
                                }
                                function withdraw(uint256 amount)
                                    external
                                {
                                    require(balanceOf[msg.sender] >= amount, "TestWeth/INSUFFICIENT_FUNDS");
                                    balanceOf[msg.sender] -= amount;
                                    msg.sender.transfer(amount);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/transformers/IERC20Transformer.sol";
                            import "./TestMintableERC20Token.sol";
                            import "./TestTransformerHost.sol";
                            import "./TestWeth.sol";
                            contract TestWethTransformerHost is
                                TestTransformerHost
                            {
                                // solhint-disable
                                TestWeth private immutable _weth;
                                // solhint-enable
                                constructor(TestWeth weth) public {
                                    _weth = weth;
                                }
                                function executeTransform(
                                    uint256 wethAmount,
                                    IERC20Transformer transformer,
                                    bytes calldata data
                                )
                                    external
                                    payable
                                {
                                    if (wethAmount != 0) {
                                        _weth.deposit{value: wethAmount}();
                                    }
                                    // Have to make this call externally because transformers aren't payable.
                                    this.rawExecuteTransform(transformer, bytes32(0), msg.sender, data);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/fixins/FixinCommon.sol";
                            import "../src/ZeroEx.sol";
                            contract TestZeroExFeature is
                                FixinCommon
                            {
                                event PayableFnCalled(uint256 value);
                                event NotPayableFnCalled();
                                function payableFn()
                                    external
                                    payable
                                {
                                    emit PayableFnCalled(msg.value);
                                }
                                function notPayableFn()
                                    external
                                {
                                    emit NotPayableFnCalled();
                                }
                                // solhint-disable no-empty-blocks
                                function unimplmentedFn()
                                    external
                                {}
                                function internalFn()
                                    external
                                    onlySelf
                                {}
                            }
                            

                            File 2 of 9: TransformERC20Feature
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            import "../errors/LibTransformERC20RichErrors.sol";
                            import "../fixins/FixinCommon.sol";
                            import "../fixins/FixinTokenSpender.sol";
                            import "../migrations/LibMigrate.sol";
                            import "../external/IFlashWallet.sol";
                            import "../external/FlashWallet.sol";
                            import "../storage/LibTransformERC20Storage.sol";
                            import "../transformers/IERC20Transformer.sol";
                            import "../transformers/LibERC20Transformer.sol";
                            import "./interfaces/IFeature.sol";
                            import "./interfaces/ITransformERC20Feature.sol";
                            /// @dev Feature to composably transform between ERC20 tokens.
                            contract TransformERC20Feature is
                                IFeature,
                                ITransformERC20Feature,
                                FixinCommon,
                                FixinTokenSpender
                            {
                                using LibSafeMathV06 for uint256;
                                using LibRichErrorsV06 for bytes;
                                /// @dev Stack vars for `_transformERC20Private()`.
                                struct TransformERC20PrivateState {
                                    IFlashWallet wallet;
                                    address transformerDeployer;
                                    uint256 recipientOutputTokenBalanceBefore;
                                    uint256 recipientOutputTokenBalanceAfter;
                                }
                                /// @dev Name of this feature.
                                string public constant override FEATURE_NAME = "TransformERC20";
                                /// @dev Version of this feature.
                                uint256 public immutable override FEATURE_VERSION = _encodeVersion(1, 4, 0);
                                /// @dev Initialize and register this feature.
                                ///      Should be delegatecalled by `Migrate.migrate()`.
                                /// @param transformerDeployer The trusted deployer for transformers.
                                /// @return success `LibMigrate.SUCCESS` on success.
                                function migrate(address transformerDeployer)
                                    external
                                    returns (bytes4 success)
                                {
                                    _registerFeatureFunction(this.getTransformerDeployer.selector);
                                    _registerFeatureFunction(this.createTransformWallet.selector);
                                    _registerFeatureFunction(this.getTransformWallet.selector);
                                    _registerFeatureFunction(this.setTransformerDeployer.selector);
                                    _registerFeatureFunction(this.setQuoteSigner.selector);
                                    _registerFeatureFunction(this.getQuoteSigner.selector);
                                    _registerFeatureFunction(this.transformERC20Staging.selector);
                                    _registerFeatureFunction(this._transformERC20.selector);
                                    if (this.getTransformWallet() == IFlashWallet(address(0))) {
                                        // Create the transform wallet if it doesn't exist.
                                        this.createTransformWallet();
                                    }
                                    LibTransformERC20Storage.getStorage().transformerDeployer = transformerDeployer;
                                    return LibMigrate.MIGRATE_SUCCESS;
                                }
                                /// @dev Replace the allowed deployer for transformers.
                                ///      Only callable by the owner.
                                /// @param transformerDeployer The address of the trusted deployer for transformers.
                                function setTransformerDeployer(address transformerDeployer)
                                    external
                                    override
                                    onlyOwner
                                {
                                    LibTransformERC20Storage.getStorage().transformerDeployer = transformerDeployer;
                                    emit TransformerDeployerUpdated(transformerDeployer);
                                }
                                /// @dev Replace the optional signer for `transformERC20()` calldata.
                                ///      Only callable by the owner.
                                /// @param quoteSigner The address of the new calldata signer.
                                function setQuoteSigner(address quoteSigner)
                                    external
                                    override
                                    onlyOwner
                                {
                                    LibTransformERC20Storage.getStorage().quoteSigner = quoteSigner;
                                    emit QuoteSignerUpdated(quoteSigner);
                                }
                                /// @dev Return the allowed deployer for transformers.
                                /// @return deployer The transform deployer address.
                                function getTransformerDeployer()
                                    public
                                    override
                                    view
                                    returns (address deployer)
                                {
                                    return LibTransformERC20Storage.getStorage().transformerDeployer;
                                }
                                /// @dev Return the optional signer for `transformERC20()` calldata.
                                /// @return signer The signer address.
                                function getQuoteSigner()
                                    public
                                    override
                                    view
                                    returns (address signer)
                                {
                                    return LibTransformERC20Storage.getStorage().quoteSigner;
                                }
                                /// @dev Deploy a new wallet instance and replace the current one with it.
                                ///      Useful if we somehow break the current wallet instance.
                                ///      Only callable by the owner.
                                /// @return wallet The new wallet instance.
                                function createTransformWallet()
                                    public
                                    override
                                    onlyOwner
                                    returns (IFlashWallet wallet)
                                {
                                    wallet = new FlashWallet();
                                    LibTransformERC20Storage.getStorage().wallet = wallet;
                                }
                                /// @dev Wrapper for `transformERC20`. This selector will be temporarily
                                ///      registered to the Exchange Proxy so that we can migrate 0x API
                                ///      with no downtime. Once 0x API has been updated to point to this
                                ///      function, we can safely re-register `transformERC20`, point 
                                ///      0x API back to `transformERC20`, and deregister this function.
                                /// @param inputToken The token being provided by the sender.
                                ///        If `0xeee...`, ETH is implied and should be provided with the call.`
                                /// @param outputToken The token to be acquired by the sender.
                                ///        `0xeee...` implies ETH.
                                /// @param inputTokenAmount The amount of `inputToken` to take from the sender.
                                ///        If set to `uint256(-1)`, the entire spendable balance of the taker
                                ///        will be solt.
                                /// @param minOutputTokenAmount The minimum amount of `outputToken` the sender
                                ///        must receive for the entire transformation to succeed. If set to zero,
                                ///        the minimum output token transfer will not be asserted.
                                /// @param transformations The transformations to execute on the token balance(s)
                                ///        in sequence.
                                /// @return outputTokenAmount The amount of `outputToken` received by the sender.
                                function transformERC20Staging(
                                    IERC20TokenV06 inputToken,
                                    IERC20TokenV06 outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 minOutputTokenAmount,
                                    Transformation[] memory transformations
                                )
                                    public
                                    payable
                                    returns (uint256 outputTokenAmount)
                                {
                                    return transformERC20(
                                        inputToken, 
                                        outputToken, 
                                        inputTokenAmount, 
                                        minOutputTokenAmount, 
                                        transformations
                                    );
                                }
                                /// @dev Executes a series of transformations to convert an ERC20 `inputToken`
                                ///      to an ERC20 `outputToken`.
                                /// @param inputToken The token being provided by the sender.
                                ///        If `0xeee...`, ETH is implied and should be provided with the call.`
                                /// @param outputToken The token to be acquired by the sender.
                                ///        `0xeee...` implies ETH.
                                /// @param inputTokenAmount The amount of `inputToken` to take from the sender.
                                ///        If set to `uint256(-1)`, the entire spendable balance of the taker
                                ///        will be solt.
                                /// @param minOutputTokenAmount The minimum amount of `outputToken` the sender
                                ///        must receive for the entire transformation to succeed. If set to zero,
                                ///        the minimum output token transfer will not be asserted.
                                /// @param transformations The transformations to execute on the token balance(s)
                                ///        in sequence.
                                /// @return outputTokenAmount The amount of `outputToken` received by the sender.
                                function transformERC20(
                                    IERC20TokenV06 inputToken,
                                    IERC20TokenV06 outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 minOutputTokenAmount,
                                    Transformation[] memory transformations
                                )
                                    public
                                    override
                                    payable
                                    returns (uint256 outputTokenAmount)
                                {
                                    return _transformERC20Private(
                                        TransformERC20Args({
                                            taker: msg.sender,
                                            inputToken: inputToken,
                                            outputToken: outputToken,
                                            inputTokenAmount: inputTokenAmount,
                                            minOutputTokenAmount: minOutputTokenAmount,
                                            transformations: transformations,
                                            useSelfBalance: false,
                                            recipient: msg.sender
                                        })
                                    );
                                }
                                /// @dev Internal version of `transformERC20()`. Only callable from within.
                                /// @param args A `TransformERC20Args` struct.
                                /// @return outputTokenAmount The amount of `outputToken` received by the taker.
                                function _transformERC20(TransformERC20Args memory args)
                                    public
                                    virtual
                                    override
                                    payable
                                    onlySelf
                                    returns (uint256 outputTokenAmount)
                                {
                                    return _transformERC20Private(args);
                                }
                                /// @dev Private version of `transformERC20()`.
                                /// @param args A `TransformERC20Args` struct.
                                /// @return outputTokenAmount The amount of `outputToken` received by the taker.
                                function _transformERC20Private(TransformERC20Args memory args)
                                    private
                                    returns (uint256 outputTokenAmount)
                                {
                                    // If the input token amount is -1 and we are not selling ETH,
                                    // transform the taker's entire spendable balance.
                                    if (!args.useSelfBalance && args.inputTokenAmount == uint256(-1)) {
                                        if (LibERC20Transformer.isTokenETH(args.inputToken)) {
                                            // We can't pull more ETH from the taker, so we just set the
                                            // input token amount to the value attached to the call.
                                            args.inputTokenAmount = msg.value;
                                        } else {
                                            args.inputTokenAmount = _getSpendableERC20BalanceOf(
                                                args.inputToken,
                                                args.taker
                                            );
                                        }
                                    }
                                    TransformERC20PrivateState memory state;
                                    state.wallet = getTransformWallet();
                                    state.transformerDeployer = getTransformerDeployer();
                                    // Remember the initial output token balance of the recipient.
                                    state.recipientOutputTokenBalanceBefore =
                                        LibERC20Transformer.getTokenBalanceOf(args.outputToken, args.recipient);
                                    // Pull input tokens from the taker to the wallet and transfer attached ETH.
                                    _transferInputTokensAndAttachedEth(args, address(state.wallet));
                                    {
                                        // Perform transformations.
                                        for (uint256 i = 0; i < args.transformations.length; ++i) {
                                            _executeTransformation(
                                                state.wallet,
                                                args.transformations[i],
                                                state.transformerDeployer,
                                                args.recipient
                                            );
                                        }
                                        // Transfer output tokens from wallet to recipient
                                        outputTokenAmount = _executeOutputTokenTransfer(
                                            args.outputToken, 
                                            state.wallet, 
                                            args.recipient
                                        );
                                    }
                                    // Compute how much output token has been transferred to the recipient.
                                    state.recipientOutputTokenBalanceAfter =
                                        LibERC20Transformer.getTokenBalanceOf(args.outputToken, args.recipient);
                                    if (state.recipientOutputTokenBalanceAfter < state.recipientOutputTokenBalanceBefore) {
                                        LibTransformERC20RichErrors.NegativeTransformERC20OutputError(
                                            address(args.outputToken),
                                            state.recipientOutputTokenBalanceBefore - state.recipientOutputTokenBalanceAfter
                                        ).rrevert();
                                    }
                                    outputTokenAmount = LibSafeMathV06.min256(
                                        outputTokenAmount,
                                        state.recipientOutputTokenBalanceAfter.safeSub(state.recipientOutputTokenBalanceBefore)
                                    );
                                    // Ensure enough output token has been sent to the taker.
                                    if (outputTokenAmount < args.minOutputTokenAmount) {
                                        LibTransformERC20RichErrors.IncompleteTransformERC20Error(
                                            address(args.outputToken),
                                            outputTokenAmount,
                                            args.minOutputTokenAmount
                                        ).rrevert();
                                    }
                                    // Emit an event.
                                    emit TransformedERC20(
                                        args.taker,
                                        address(args.inputToken),
                                        address(args.outputToken),
                                        args.inputTokenAmount,
                                        outputTokenAmount
                                    );
                                }
                                /// @dev Return the current wallet instance that will serve as the execution
                                ///      context for transformations.
                                /// @return wallet The wallet instance.
                                function getTransformWallet()
                                    public
                                    override
                                    view
                                    returns (IFlashWallet wallet)
                                {
                                    return LibTransformERC20Storage.getStorage().wallet;
                                }
                                /// @dev Transfer input tokens and any attached ETH to `to`
                                /// @param args A `TransformERC20Args` struct.
                                /// @param to The recipient of tokens and ETH.
                                function _transferInputTokensAndAttachedEth(
                                    TransformERC20Args memory args,
                                    address payable to
                                )
                                    private
                                {
                                    if (
                                        LibERC20Transformer.isTokenETH(args.inputToken) &&
                                        msg.value < args.inputTokenAmount
                                    ) {
                                         // Token is ETH, so the caller must attach enough ETH to the call.
                                        LibTransformERC20RichErrors.InsufficientEthAttachedError(
                                            msg.value,
                                            args.inputTokenAmount
                                        ).rrevert();
                                    }
                                    // Transfer any attached ETH.
                                    if (msg.value != 0) {
                                        to.transfer(msg.value);
                                    }
                                    // Transfer input tokens.
                                    if (!LibERC20Transformer.isTokenETH(args.inputToken)) {
                                        if (args.useSelfBalance) {
                                            // Use EP balance input token.
                                            _transferERC20Tokens(
                                                args.inputToken,
                                                to,
                                                args.inputTokenAmount
                                            );
                                        } else {
                                            // Pull ERC20 tokens from taker.
                                            _transferERC20TokensFrom(
                                                args.inputToken,
                                                args.taker,
                                                to,
                                                args.inputTokenAmount
                                            );
                                        }
                                    }
                                }
                                /// @dev Executs a transformer in the context of `wallet`.
                                /// @param wallet The wallet instance.
                                /// @param transformation The transformation.
                                /// @param transformerDeployer The address of the transformer deployer.
                                /// @param recipient The recipient address.
                                function _executeTransformation(
                                    IFlashWallet wallet,
                                    Transformation memory transformation,
                                    address transformerDeployer,
                                    address payable recipient
                                )
                                    private
                                {
                                    // Derive the transformer address from the deployment nonce.
                                    address payable transformer = LibERC20Transformer.getDeployedAddress(
                                        transformerDeployer,
                                        transformation.deploymentNonce
                                    );
                                    // Call `transformer.transform()` as the wallet.
                                    bytes memory resultData = wallet.executeDelegateCall(
                                        // The call target.
                                        transformer,
                                        // Call data.
                                        abi.encodeWithSelector(
                                            IERC20Transformer.transform.selector,
                                            IERC20Transformer.TransformContext({
                                                sender: msg.sender,
                                                recipient: recipient,
                                                data: transformation.data
                                            })
                                        )
                                    );
                                    // Ensure the transformer returned the magic bytes.
                                    if (resultData.length != 32 ||
                                        abi.decode(resultData, (bytes4)) != LibERC20Transformer.TRANSFORMER_SUCCESS
                                    ) {
                                        LibTransformERC20RichErrors.TransformerFailedError(
                                            transformer,
                                            transformation.data,
                                            resultData
                                        ).rrevert();
                                    }
                                }
                                function _executeOutputTokenTransfer(
                                    IERC20TokenV06 outputToken,
                                    IFlashWallet wallet,
                                    address payable recipient
                                )
                                    private
                                    returns (uint256 transferAmount)
                                {
                                    transferAmount =
                                        LibERC20Transformer.getTokenBalanceOf(outputToken, address(wallet));
                                    if (LibERC20Transformer.isTokenETH(outputToken)) {
                                        wallet.executeCall(
                                            recipient,
                                            "",
                                            transferAmount
                                        );
                                    } else {
                                        bytes memory resultData = wallet.executeCall(
                                            payable(address(outputToken)),
                                            abi.encodeWithSelector(
                                                IERC20TokenV06.transfer.selector,
                                                recipient,
                                                transferAmount
                                            ),
                                            0
                                        );
                                        if (resultData.length == 0) {
                                            // If we get back 0 returndata, this may be a non-standard ERC-20 that
                                            // does not return a boolean. Check that it at least contains code.
                                            uint256 size;
                                            assembly { size := extcodesize(outputToken) }
                                            require(size > 0, "invalid token address, contains no code");
                                        } else if (resultData.length >= 32) {
                                            // If we get back at least 32 bytes, we know the target address
                                            // contains code, and we assume it is a token that returned a boolean
                                            // success value, which must be true.
                                            uint256 result = LibBytesV06.readUint256(resultData, 0);
                                            if (result != 1) {
                                                LibRichErrorsV06.rrevert(resultData);
                                            }
                                        } else {
                                            // If 0 < returndatasize < 32, the target is a contract, but not a
                                            // valid token.
                                            LibRichErrorsV06.rrevert(resultData);
                                        }
                                    }
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            interface IERC20TokenV06 {
                                // solhint-disable no-simple-event-func-name
                                event Transfer(
                                    address indexed from,
                                    address indexed to,
                                    uint256 value
                                );
                                event Approval(
                                    address indexed owner,
                                    address indexed spender,
                                    uint256 value
                                );
                                /// @dev send `value` token to `to` from `msg.sender`
                                /// @param to The address of the recipient
                                /// @param value The amount of token to be transferred
                                /// @return True if transfer was successful
                                function transfer(address to, uint256 value)
                                    external
                                    returns (bool);
                                /// @dev send `value` token to `to` from `from` on the condition it is approved by `from`
                                /// @param from The address of the sender
                                /// @param to The address of the recipient
                                /// @param value The amount of token to be transferred
                                /// @return True if transfer was successful
                                function transferFrom(
                                    address from,
                                    address to,
                                    uint256 value
                                )
                                    external
                                    returns (bool);
                                /// @dev `msg.sender` approves `spender` to spend `value` tokens
                                /// @param spender The address of the account able to transfer the tokens
                                /// @param value The amount of wei to be approved for transfer
                                /// @return Always true if the call has enough gas to complete execution
                                function approve(address spender, uint256 value)
                                    external
                                    returns (bool);
                                /// @dev Query total supply of token
                                /// @return Total supply of token
                                function totalSupply()
                                    external
                                    view
                                    returns (uint256);
                                /// @dev Get the balance of `owner`.
                                /// @param owner The address from which the balance will be retrieved
                                /// @return Balance of owner
                                function balanceOf(address owner)
                                    external
                                    view
                                    returns (uint256);
                                /// @dev Get the allowance for `spender` to spend from `owner`.
                                /// @param owner The address of the account owning tokens
                                /// @param spender The address of the account able to transfer the tokens
                                /// @return Amount of remaining tokens allowed to spent
                                function allowance(address owner, address spender)
                                    external
                                    view
                                    returns (uint256);
                                /// @dev Get the number of decimals this token has.
                                function decimals()
                                    external
                                    view
                                    returns (uint8);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
                            import "./IERC20TokenV06.sol";
                            library LibERC20TokenV06 {
                                bytes constant private DECIMALS_CALL_DATA = hex"313ce567";
                                /// @dev Calls `IERC20TokenV06(token).approve()`.
                                ///      Reverts if the return data is invalid or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param spender The address that receives an allowance.
                                /// @param allowance The allowance to set.
                                function compatApprove(
                                    IERC20TokenV06 token,
                                    address spender,
                                    uint256 allowance
                                )
                                    internal
                                {
                                    bytes memory callData = abi.encodeWithSelector(
                                        token.approve.selector,
                                        spender,
                                        allowance
                                    );
                                    _callWithOptionalBooleanResult(address(token), callData);
                                }
                                /// @dev Calls `IERC20TokenV06(token).approve()` and sets the allowance to the
                                ///      maximum if the current approval is not already >= an amount.
                                ///      Reverts if the return data is invalid or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param spender The address that receives an allowance.
                                /// @param amount The minimum allowance needed.
                                function approveIfBelow(
                                    IERC20TokenV06 token,
                                    address spender,
                                    uint256 amount
                                )
                                    internal
                                {
                                    if (token.allowance(address(this), spender) < amount) {
                                        compatApprove(token, spender, uint256(-1));
                                    }
                                }
                                /// @dev Calls `IERC20TokenV06(token).transfer()`.
                                ///      Reverts if the return data is invalid or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param to The address that receives the tokens
                                /// @param amount Number of tokens to transfer.
                                function compatTransfer(
                                    IERC20TokenV06 token,
                                    address to,
                                    uint256 amount
                                )
                                    internal
                                {
                                    bytes memory callData = abi.encodeWithSelector(
                                        token.transfer.selector,
                                        to,
                                        amount
                                    );
                                    _callWithOptionalBooleanResult(address(token), callData);
                                }
                                /// @dev Calls `IERC20TokenV06(token).transferFrom()`.
                                ///      Reverts if the return data is invalid or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param from The owner of the tokens.
                                /// @param to The address that receives the tokens
                                /// @param amount Number of tokens to transfer.
                                function compatTransferFrom(
                                    IERC20TokenV06 token,
                                    address from,
                                    address to,
                                    uint256 amount
                                )
                                    internal
                                {
                                    bytes memory callData = abi.encodeWithSelector(
                                        token.transferFrom.selector,
                                        from,
                                        to,
                                        amount
                                    );
                                    _callWithOptionalBooleanResult(address(token), callData);
                                }
                                /// @dev Retrieves the number of decimals for a token.
                                ///      Returns `18` if the call reverts.
                                /// @param token The address of the token contract.
                                /// @return tokenDecimals The number of decimals places for the token.
                                function compatDecimals(IERC20TokenV06 token)
                                    internal
                                    view
                                    returns (uint8 tokenDecimals)
                                {
                                    tokenDecimals = 18;
                                    (bool didSucceed, bytes memory resultData) = address(token).staticcall(DECIMALS_CALL_DATA);
                                    if (didSucceed && resultData.length >= 32) {
                                        tokenDecimals = uint8(LibBytesV06.readUint256(resultData, 0));
                                    }
                                }
                                /// @dev Retrieves the allowance for a token, owner, and spender.
                                ///      Returns `0` if the call reverts.
                                /// @param token The address of the token contract.
                                /// @param owner The owner of the tokens.
                                /// @param spender The address the spender.
                                /// @return allowance_ The allowance for a token, owner, and spender.
                                function compatAllowance(IERC20TokenV06 token, address owner, address spender)
                                    internal
                                    view
                                    returns (uint256 allowance_)
                                {
                                    (bool didSucceed, bytes memory resultData) = address(token).staticcall(
                                        abi.encodeWithSelector(
                                            token.allowance.selector,
                                            owner,
                                            spender
                                        )
                                    );
                                    if (didSucceed && resultData.length >= 32) {
                                        allowance_ = LibBytesV06.readUint256(resultData, 0);
                                    }
                                }
                                /// @dev Retrieves the balance for a token owner.
                                ///      Returns `0` if the call reverts.
                                /// @param token The address of the token contract.
                                /// @param owner The owner of the tokens.
                                /// @return balance The token balance of an owner.
                                function compatBalanceOf(IERC20TokenV06 token, address owner)
                                    internal
                                    view
                                    returns (uint256 balance)
                                {
                                    (bool didSucceed, bytes memory resultData) = address(token).staticcall(
                                        abi.encodeWithSelector(
                                            token.balanceOf.selector,
                                            owner
                                        )
                                    );
                                    if (didSucceed && resultData.length >= 32) {
                                        balance = LibBytesV06.readUint256(resultData, 0);
                                    }
                                }
                                /// @dev Executes a call on address `target` with calldata `callData`
                                ///      and asserts that either nothing was returned or a single boolean
                                ///      was returned equal to `true`.
                                /// @param target The call target.
                                /// @param callData The abi-encoded call data.
                                function _callWithOptionalBooleanResult(
                                    address target,
                                    bytes memory callData
                                )
                                    private
                                {
                                    (bool didSucceed, bytes memory resultData) = target.call(callData);
                                    // Revert if the call reverted.
                                    if (!didSucceed) {
                                        LibRichErrorsV06.rrevert(resultData);
                                    }
                                    // If we get back 0 returndata, this may be a non-standard ERC-20 that
                                    // does not return a boolean. Check that it at least contains code.
                                    if (resultData.length == 0) {
                                        uint256 size;
                                        assembly { size := extcodesize(target) }
                                        require(size > 0, "invalid token address, contains no code");
                                        return;
                                    }
                                    // If we get back at least 32 bytes, we know the target address
                                    // contains code, and we assume it is a token that returned a boolean
                                    // success value, which must be true.
                                    if (resultData.length >= 32) {
                                        uint256 result = LibBytesV06.readUint256(resultData, 0);
                                        if (result == 1) {
                                            return;
                                        } else {
                                            LibRichErrorsV06.rrevert(resultData);
                                        }
                                    }
                                    // If 0 < returndatasize < 32, the target is a contract, but not a
                                    // valid token.
                                    LibRichErrorsV06.rrevert(resultData);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibRichErrorsV06 {
                                // bytes4(keccak256("Error(string)"))
                                bytes4 internal constant STANDARD_ERROR_SELECTOR = 0x08c379a0;
                                // solhint-disable func-name-mixedcase
                                /// @dev ABI encode a standard, string revert error payload.
                                ///      This is the same payload that would be included by a `revert(string)`
                                ///      solidity statement. It has the function signature `Error(string)`.
                                /// @param message The error string.
                                /// @return The ABI encoded error.
                                function StandardError(string memory message)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        STANDARD_ERROR_SELECTOR,
                                        bytes(message)
                                    );
                                }
                                // solhint-enable func-name-mixedcase
                                /// @dev Reverts an encoded rich revert reason `errorData`.
                                /// @param errorData ABI encoded error data.
                                function rrevert(bytes memory errorData)
                                    internal
                                    pure
                                {
                                    assembly {
                                        revert(add(errorData, 0x20), mload(errorData))
                                    }
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./errors/LibBytesRichErrorsV06.sol";
                            import "./errors/LibRichErrorsV06.sol";
                            library LibBytesV06 {
                                using LibBytesV06 for bytes;
                                /// @dev Gets the memory address for a byte array.
                                /// @param input Byte array to lookup.
                                /// @return memoryAddress Memory address of byte array. This
                                ///         points to the header of the byte array which contains
                                ///         the length.
                                function rawAddress(bytes memory input)
                                    internal
                                    pure
                                    returns (uint256 memoryAddress)
                                {
                                    assembly {
                                        memoryAddress := input
                                    }
                                    return memoryAddress;
                                }
                                /// @dev Gets the memory address for the contents of a byte array.
                                /// @param input Byte array to lookup.
                                /// @return memoryAddress Memory address of the contents of the byte array.
                                function contentAddress(bytes memory input)
                                    internal
                                    pure
                                    returns (uint256 memoryAddress)
                                {
                                    assembly {
                                        memoryAddress := add(input, 32)
                                    }
                                    return memoryAddress;
                                }
                                /// @dev Copies `length` bytes from memory location `source` to `dest`.
                                /// @param dest memory address to copy bytes to.
                                /// @param source memory address to copy bytes from.
                                /// @param length number of bytes to copy.
                                function memCopy(
                                    uint256 dest,
                                    uint256 source,
                                    uint256 length
                                )
                                    internal
                                    pure
                                {
                                    if (length < 32) {
                                        // Handle a partial word by reading destination and masking
                                        // off the bits we are interested in.
                                        // This correctly handles overlap, zero lengths and source == dest
                                        assembly {
                                            let mask := sub(exp(256, sub(32, length)), 1)
                                            let s := and(mload(source), not(mask))
                                            let d := and(mload(dest), mask)
                                            mstore(dest, or(s, d))
                                        }
                                    } else {
                                        // Skip the O(length) loop when source == dest.
                                        if (source == dest) {
                                            return;
                                        }
                                        // For large copies we copy whole words at a time. The final
                                        // word is aligned to the end of the range (instead of after the
                                        // previous) to handle partial words. So a copy will look like this:
                                        //
                                        //  ####
                                        //      ####
                                        //          ####
                                        //            ####
                                        //
                                        // We handle overlap in the source and destination range by
                                        // changing the copying direction. This prevents us from
                                        // overwriting parts of source that we still need to copy.
                                        //
                                        // This correctly handles source == dest
                                        //
                                        if (source > dest) {
                                            assembly {
                                                // We subtract 32 from `sEnd` and `dEnd` because it
                                                // is easier to compare with in the loop, and these
                                                // are also the addresses we need for copying the
                                                // last bytes.
                                                length := sub(length, 32)
                                                let sEnd := add(source, length)
                                                let dEnd := add(dest, length)
                                                // Remember the last 32 bytes of source
                                                // This needs to be done here and not after the loop
                                                // because we may have overwritten the last bytes in
                                                // source already due to overlap.
                                                let last := mload(sEnd)
                                                // Copy whole words front to back
                                                // Note: the first check is always true,
                                                // this could have been a do-while loop.
                                                // solhint-disable-next-line no-empty-blocks
                                                for {} lt(source, sEnd) {} {
                                                    mstore(dest, mload(source))
                                                    source := add(source, 32)
                                                    dest := add(dest, 32)
                                                }
                                                // Write the last 32 bytes
                                                mstore(dEnd, last)
                                            }
                                        } else {
                                            assembly {
                                                // We subtract 32 from `sEnd` and `dEnd` because those
                                                // are the starting points when copying a word at the end.
                                                length := sub(length, 32)
                                                let sEnd := add(source, length)
                                                let dEnd := add(dest, length)
                                                // Remember the first 32 bytes of source
                                                // This needs to be done here and not after the loop
                                                // because we may have overwritten the first bytes in
                                                // source already due to overlap.
                                                let first := mload(source)
                                                // Copy whole words back to front
                                                // We use a signed comparisson here to allow dEnd to become
                                                // negative (happens when source and dest < 32). Valid
                                                // addresses in local memory will never be larger than
                                                // 2**255, so they can be safely re-interpreted as signed.
                                                // Note: the first check is always true,
                                                // this could have been a do-while loop.
                                                // solhint-disable-next-line no-empty-blocks
                                                for {} slt(dest, dEnd) {} {
                                                    mstore(dEnd, mload(sEnd))
                                                    sEnd := sub(sEnd, 32)
                                                    dEnd := sub(dEnd, 32)
                                                }
                                                // Write the first 32 bytes
                                                mstore(dest, first)
                                            }
                                        }
                                    }
                                }
                                /// @dev Returns a slices from a byte array.
                                /// @param b The byte array to take a slice from.
                                /// @param from The starting index for the slice (inclusive).
                                /// @param to The final index for the slice (exclusive).
                                /// @return result The slice containing bytes at indices [from, to)
                                function slice(
                                    bytes memory b,
                                    uint256 from,
                                    uint256 to
                                )
                                    internal
                                    pure
                                    returns (bytes memory result)
                                {
                                    // Ensure that the from and to positions are valid positions for a slice within
                                    // the byte array that is being used.
                                    if (from > to) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.FromLessThanOrEqualsToRequired,
                                            from,
                                            to
                                        ));
                                    }
                                    if (to > b.length) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.ToLessThanOrEqualsLengthRequired,
                                            to,
                                            b.length
                                        ));
                                    }
                                    // Create a new bytes structure and copy contents
                                    result = new bytes(to - from);
                                    memCopy(
                                        result.contentAddress(),
                                        b.contentAddress() + from,
                                        result.length
                                    );
                                    return result;
                                }
                                /// @dev Returns a slice from a byte array without preserving the input.
                                ///      When `from == 0`, the original array will match the slice.
                                ///      In other cases its state will be corrupted.
                                /// @param b The byte array to take a slice from. Will be destroyed in the process.
                                /// @param from The starting index for the slice (inclusive).
                                /// @param to The final index for the slice (exclusive).
                                /// @return result The slice containing bytes at indices [from, to)
                                function sliceDestructive(
                                    bytes memory b,
                                    uint256 from,
                                    uint256 to
                                )
                                    internal
                                    pure
                                    returns (bytes memory result)
                                {
                                    // Ensure that the from and to positions are valid positions for a slice within
                                    // the byte array that is being used.
                                    if (from > to) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.FromLessThanOrEqualsToRequired,
                                            from,
                                            to
                                        ));
                                    }
                                    if (to > b.length) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.ToLessThanOrEqualsLengthRequired,
                                            to,
                                            b.length
                                        ));
                                    }
                                    // Create a new bytes structure around [from, to) in-place.
                                    assembly {
                                        result := add(b, from)
                                        mstore(result, sub(to, from))
                                    }
                                    return result;
                                }
                                /// @dev Pops the last byte off of a byte array by modifying its length.
                                /// @param b Byte array that will be modified.
                                /// @return result The byte that was popped off.
                                function popLastByte(bytes memory b)
                                    internal
                                    pure
                                    returns (bytes1 result)
                                {
                                    if (b.length == 0) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanZeroRequired,
                                            b.length,
                                            0
                                        ));
                                    }
                                    // Store last byte.
                                    result = b[b.length - 1];
                                    assembly {
                                        // Decrement length of byte array.
                                        let newLen := sub(mload(b), 1)
                                        mstore(b, newLen)
                                    }
                                    return result;
                                }
                                /// @dev Tests equality of two byte arrays.
                                /// @param lhs First byte array to compare.
                                /// @param rhs Second byte array to compare.
                                /// @return equal True if arrays are the same. False otherwise.
                                function equals(
                                    bytes memory lhs,
                                    bytes memory rhs
                                )
                                    internal
                                    pure
                                    returns (bool equal)
                                {
                                    // Keccak gas cost is 30 + numWords * 6. This is a cheap way to compare.
                                    // We early exit on unequal lengths, but keccak would also correctly
                                    // handle this.
                                    return lhs.length == rhs.length && keccak256(lhs) == keccak256(rhs);
                                }
                                /// @dev Reads an address from a position in a byte array.
                                /// @param b Byte array containing an address.
                                /// @param index Index in byte array of address.
                                /// @return result address from byte array.
                                function readAddress(
                                    bytes memory b,
                                    uint256 index
                                )
                                    internal
                                    pure
                                    returns (address result)
                                {
                                    if (b.length < index + 20) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsTwentyRequired,
                                            b.length,
                                            index + 20 // 20 is length of address
                                        ));
                                    }
                                    // Add offset to index:
                                    // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
                                    // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
                                    index += 20;
                                    // Read address from array memory
                                    assembly {
                                        // 1. Add index to address of bytes array
                                        // 2. Load 32-byte word from memory
                                        // 3. Apply 20-byte mask to obtain address
                                        result := and(mload(add(b, index)), 0xffffffffffffffffffffffffffffffffffffffff)
                                    }
                                    return result;
                                }
                                /// @dev Writes an address into a specific position in a byte array.
                                /// @param b Byte array to insert address into.
                                /// @param index Index in byte array of address.
                                /// @param input Address to put into byte array.
                                function writeAddress(
                                    bytes memory b,
                                    uint256 index,
                                    address input
                                )
                                    internal
                                    pure
                                {
                                    if (b.length < index + 20) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsTwentyRequired,
                                            b.length,
                                            index + 20 // 20 is length of address
                                        ));
                                    }
                                    // Add offset to index:
                                    // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
                                    // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
                                    index += 20;
                                    // Store address into array memory
                                    assembly {
                                        // The address occupies 20 bytes and mstore stores 32 bytes.
                                        // First fetch the 32-byte word where we'll be storing the address, then
                                        // apply a mask so we have only the bytes in the word that the address will not occupy.
                                        // Then combine these bytes with the address and store the 32 bytes back to memory with mstore.
                                        // 1. Add index to address of bytes array
                                        // 2. Load 32-byte word from memory
                                        // 3. Apply 12-byte mask to obtain extra bytes occupying word of memory where we'll store the address
                                        let neighbors := and(
                                            mload(add(b, index)),
                                            0xffffffffffffffffffffffff0000000000000000000000000000000000000000
                                        )
                                        // Make sure input address is clean.
                                        // (Solidity does not guarantee this)
                                        input := and(input, 0xffffffffffffffffffffffffffffffffffffffff)
                                        // Store the neighbors and address into memory
                                        mstore(add(b, index), xor(input, neighbors))
                                    }
                                }
                                /// @dev Reads a bytes32 value from a position in a byte array.
                                /// @param b Byte array containing a bytes32 value.
                                /// @param index Index in byte array of bytes32 value.
                                /// @return result bytes32 value from byte array.
                                function readBytes32(
                                    bytes memory b,
                                    uint256 index
                                )
                                    internal
                                    pure
                                    returns (bytes32 result)
                                {
                                    if (b.length < index + 32) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsThirtyTwoRequired,
                                            b.length,
                                            index + 32
                                        ));
                                    }
                                    // Arrays are prefixed by a 256 bit length parameter
                                    index += 32;
                                    // Read the bytes32 from array memory
                                    assembly {
                                        result := mload(add(b, index))
                                    }
                                    return result;
                                }
                                /// @dev Writes a bytes32 into a specific position in a byte array.
                                /// @param b Byte array to insert <input> into.
                                /// @param index Index in byte array of <input>.
                                /// @param input bytes32 to put into byte array.
                                function writeBytes32(
                                    bytes memory b,
                                    uint256 index,
                                    bytes32 input
                                )
                                    internal
                                    pure
                                {
                                    if (b.length < index + 32) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsThirtyTwoRequired,
                                            b.length,
                                            index + 32
                                        ));
                                    }
                                    // Arrays are prefixed by a 256 bit length parameter
                                    index += 32;
                                    // Read the bytes32 from array memory
                                    assembly {
                                        mstore(add(b, index), input)
                                    }
                                }
                                /// @dev Reads a uint256 value from a position in a byte array.
                                /// @param b Byte array containing a uint256 value.
                                /// @param index Index in byte array of uint256 value.
                                /// @return result uint256 value from byte array.
                                function readUint256(
                                    bytes memory b,
                                    uint256 index
                                )
                                    internal
                                    pure
                                    returns (uint256 result)
                                {
                                    result = uint256(readBytes32(b, index));
                                    return result;
                                }
                                /// @dev Writes a uint256 into a specific position in a byte array.
                                /// @param b Byte array to insert <input> into.
                                /// @param index Index in byte array of <input>.
                                /// @param input uint256 to put into byte array.
                                function writeUint256(
                                    bytes memory b,
                                    uint256 index,
                                    uint256 input
                                )
                                    internal
                                    pure
                                {
                                    writeBytes32(b, index, bytes32(input));
                                }
                                /// @dev Reads an unpadded bytes4 value from a position in a byte array.
                                /// @param b Byte array containing a bytes4 value.
                                /// @param index Index in byte array of bytes4 value.
                                /// @return result bytes4 value from byte array.
                                function readBytes4(
                                    bytes memory b,
                                    uint256 index
                                )
                                    internal
                                    pure
                                    returns (bytes4 result)
                                {
                                    if (b.length < index + 4) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsFourRequired,
                                            b.length,
                                            index + 4
                                        ));
                                    }
                                    // Arrays are prefixed by a 32 byte length field
                                    index += 32;
                                    // Read the bytes4 from array memory
                                    assembly {
                                        result := mload(add(b, index))
                                        // Solidity does not require us to clean the trailing bytes.
                                        // We do it anyway
                                        result := and(result, 0xFFFFFFFF00000000000000000000000000000000000000000000000000000000)
                                    }
                                    return result;
                                }
                                /// @dev Writes a new length to a byte array.
                                ///      Decreasing length will lead to removing the corresponding lower order bytes from the byte array.
                                ///      Increasing length may lead to appending adjacent in-memory bytes to the end of the byte array.
                                /// @param b Bytes array to write new length to.
                                /// @param length New length of byte array.
                                function writeLength(bytes memory b, uint256 length)
                                    internal
                                    pure
                                {
                                    assembly {
                                        mstore(b, length)
                                    }
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibBytesRichErrorsV06 {
                                enum InvalidByteOperationErrorCodes {
                                    FromLessThanOrEqualsToRequired,
                                    ToLessThanOrEqualsLengthRequired,
                                    LengthGreaterThanZeroRequired,
                                    LengthGreaterThanOrEqualsFourRequired,
                                    LengthGreaterThanOrEqualsTwentyRequired,
                                    LengthGreaterThanOrEqualsThirtyTwoRequired,
                                    LengthGreaterThanOrEqualsNestedBytesLengthRequired,
                                    DestinationLengthGreaterThanOrEqualSourceLengthRequired
                                }
                                // bytes4(keccak256("InvalidByteOperationError(uint8,uint256,uint256)"))
                                bytes4 internal constant INVALID_BYTE_OPERATION_ERROR_SELECTOR =
                                    0x28006595;
                                // solhint-disable func-name-mixedcase
                                function InvalidByteOperationError(
                                    InvalidByteOperationErrorCodes errorCode,
                                    uint256 offset,
                                    uint256 required
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        INVALID_BYTE_OPERATION_ERROR_SELECTOR,
                                        errorCode,
                                        offset,
                                        required
                                    );
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./errors/LibRichErrorsV06.sol";
                            import "./errors/LibSafeMathRichErrorsV06.sol";
                            library LibSafeMathV06 {
                                function safeMul(uint256 a, uint256 b)
                                    internal
                                    pure
                                    returns (uint256)
                                {
                                    if (a == 0) {
                                        return 0;
                                    }
                                    uint256 c = a * b;
                                    if (c / a != b) {
                                        LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                                            LibSafeMathRichErrorsV06.BinOpErrorCodes.MULTIPLICATION_OVERFLOW,
                                            a,
                                            b
                                        ));
                                    }
                                    return c;
                                }
                                function safeDiv(uint256 a, uint256 b)
                                    internal
                                    pure
                                    returns (uint256)
                                {
                                    if (b == 0) {
                                        LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                                            LibSafeMathRichErrorsV06.BinOpErrorCodes.DIVISION_BY_ZERO,
                                            a,
                                            b
                                        ));
                                    }
                                    uint256 c = a / b;
                                    return c;
                                }
                                function safeSub(uint256 a, uint256 b)
                                    internal
                                    pure
                                    returns (uint256)
                                {
                                    if (b > a) {
                                        LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                                            LibSafeMathRichErrorsV06.BinOpErrorCodes.SUBTRACTION_UNDERFLOW,
                                            a,
                                            b
                                        ));
                                    }
                                    return a - b;
                                }
                                function safeAdd(uint256 a, uint256 b)
                                    internal
                                    pure
                                    returns (uint256)
                                {
                                    uint256 c = a + b;
                                    if (c < a) {
                                        LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                                            LibSafeMathRichErrorsV06.BinOpErrorCodes.ADDITION_OVERFLOW,
                                            a,
                                            b
                                        ));
                                    }
                                    return c;
                                }
                                function max256(uint256 a, uint256 b)
                                    internal
                                    pure
                                    returns (uint256)
                                {
                                    return a >= b ? a : b;
                                }
                                function min256(uint256 a, uint256 b)
                                    internal
                                    pure
                                    returns (uint256)
                                {
                                    return a < b ? a : b;
                                }
                                function safeMul128(uint128 a, uint128 b)
                                    internal
                                    pure
                                    returns (uint128)
                                {
                                    if (a == 0) {
                                        return 0;
                                    }
                                    uint128 c = a * b;
                                    if (c / a != b) {
                                        LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                                            LibSafeMathRichErrorsV06.BinOpErrorCodes.MULTIPLICATION_OVERFLOW,
                                            a,
                                            b
                                        ));
                                    }
                                    return c;
                                }
                                function safeDiv128(uint128 a, uint128 b)
                                    internal
                                    pure
                                    returns (uint128)
                                {
                                    if (b == 0) {
                                        LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                                            LibSafeMathRichErrorsV06.BinOpErrorCodes.DIVISION_BY_ZERO,
                                            a,
                                            b
                                        ));
                                    }
                                    uint128 c = a / b;
                                    return c;
                                }
                                function safeSub128(uint128 a, uint128 b)
                                    internal
                                    pure
                                    returns (uint128)
                                {
                                    if (b > a) {
                                        LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                                            LibSafeMathRichErrorsV06.BinOpErrorCodes.SUBTRACTION_UNDERFLOW,
                                            a,
                                            b
                                        ));
                                    }
                                    return a - b;
                                }
                                function safeAdd128(uint128 a, uint128 b)
                                    internal
                                    pure
                                    returns (uint128)
                                {
                                    uint128 c = a + b;
                                    if (c < a) {
                                        LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                                            LibSafeMathRichErrorsV06.BinOpErrorCodes.ADDITION_OVERFLOW,
                                            a,
                                            b
                                        ));
                                    }
                                    return c;
                                }
                                function max128(uint128 a, uint128 b)
                                    internal
                                    pure
                                    returns (uint128)
                                {
                                    return a >= b ? a : b;
                                }
                                function min128(uint128 a, uint128 b)
                                    internal
                                    pure
                                    returns (uint128)
                                {
                                    return a < b ? a : b;
                                }
                                function safeDowncastToUint128(uint256 a)
                                    internal
                                    pure
                                    returns (uint128)
                                {
                                    if (a > type(uint128).max) {
                                        LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256DowncastError(
                                            LibSafeMathRichErrorsV06.DowncastErrorCodes.VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT128,
                                            a
                                        ));
                                    }
                                    return uint128(a);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibSafeMathRichErrorsV06 {
                                // bytes4(keccak256("Uint256BinOpError(uint8,uint256,uint256)"))
                                bytes4 internal constant UINT256_BINOP_ERROR_SELECTOR =
                                    0xe946c1bb;
                                // bytes4(keccak256("Uint256DowncastError(uint8,uint256)"))
                                bytes4 internal constant UINT256_DOWNCAST_ERROR_SELECTOR =
                                    0xc996af7b;
                                enum BinOpErrorCodes {
                                    ADDITION_OVERFLOW,
                                    MULTIPLICATION_OVERFLOW,
                                    SUBTRACTION_UNDERFLOW,
                                    DIVISION_BY_ZERO
                                }
                                enum DowncastErrorCodes {
                                    VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT32,
                                    VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT64,
                                    VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT96,
                                    VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT128
                                }
                                // solhint-disable func-name-mixedcase
                                function Uint256BinOpError(
                                    BinOpErrorCodes errorCode,
                                    uint256 a,
                                    uint256 b
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        UINT256_BINOP_ERROR_SELECTOR,
                                        errorCode,
                                        a,
                                        b
                                    );
                                }
                                function Uint256DowncastError(
                                    DowncastErrorCodes errorCode,
                                    uint256 a
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        UINT256_DOWNCAST_ERROR_SELECTOR,
                                        errorCode,
                                        a
                                    );
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibTransformERC20RichErrors {
                                // solhint-disable func-name-mixedcase,separate-by-one-line-in-contract
                                function InsufficientEthAttachedError(
                                    uint256 ethAttached,
                                    uint256 ethNeeded
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InsufficientEthAttachedError(uint256,uint256)")),
                                        ethAttached,
                                        ethNeeded
                                    );
                                }
                                function IncompleteTransformERC20Error(
                                    address outputToken,
                                    uint256 outputTokenAmount,
                                    uint256 minOutputTokenAmount
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("IncompleteTransformERC20Error(address,uint256,uint256)")),
                                        outputToken,
                                        outputTokenAmount,
                                        minOutputTokenAmount
                                    );
                                }
                                function NegativeTransformERC20OutputError(
                                    address outputToken,
                                    uint256 outputTokenLostAmount
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("NegativeTransformERC20OutputError(address,uint256)")),
                                        outputToken,
                                        outputTokenLostAmount
                                    );
                                }
                                function TransformerFailedError(
                                    address transformer,
                                    bytes memory transformerData,
                                    bytes memory resultData
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("TransformerFailedError(address,bytes,bytes)")),
                                        transformer,
                                        transformerData,
                                        resultData
                                    );
                                }
                                // Common Transformer errors ///////////////////////////////////////////////
                                function OnlyCallableByDeployerError(
                                    address caller,
                                    address deployer
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("OnlyCallableByDeployerError(address,address)")),
                                        caller,
                                        deployer
                                    );
                                }
                                function InvalidExecutionContextError(
                                    address actualContext,
                                    address expectedContext
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InvalidExecutionContextError(address,address)")),
                                        actualContext,
                                        expectedContext
                                    );
                                }
                                enum InvalidTransformDataErrorCode {
                                    INVALID_TOKENS,
                                    INVALID_ARRAY_LENGTH
                                }
                                function InvalidTransformDataError(
                                    InvalidTransformDataErrorCode errorCode,
                                    bytes memory transformData
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InvalidTransformDataError(uint8,bytes)")),
                                        errorCode,
                                        transformData
                                    );
                                }
                                // FillQuoteTransformer errors /////////////////////////////////////////////
                                function IncompleteFillSellQuoteError(
                                    address sellToken,
                                    uint256 soldAmount,
                                    uint256 sellAmount
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("IncompleteFillSellQuoteError(address,uint256,uint256)")),
                                        sellToken,
                                        soldAmount,
                                        sellAmount
                                    );
                                }
                                function IncompleteFillBuyQuoteError(
                                    address buyToken,
                                    uint256 boughtAmount,
                                    uint256 buyAmount
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("IncompleteFillBuyQuoteError(address,uint256,uint256)")),
                                        buyToken,
                                        boughtAmount,
                                        buyAmount
                                    );
                                }
                                function InsufficientTakerTokenError(
                                    uint256 tokenBalance,
                                    uint256 tokensNeeded
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InsufficientTakerTokenError(uint256,uint256)")),
                                        tokenBalance,
                                        tokensNeeded
                                    );
                                }
                                function InsufficientProtocolFeeError(
                                    uint256 ethBalance,
                                    uint256 ethNeeded
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InsufficientProtocolFeeError(uint256,uint256)")),
                                        ethBalance,
                                        ethNeeded
                                    );
                                }
                                function InvalidERC20AssetDataError(
                                    bytes memory assetData
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InvalidERC20AssetDataError(bytes)")),
                                        assetData
                                    );
                                }
                                function InvalidTakerFeeTokenError(
                                    address token
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InvalidTakerFeeTokenError(address)")),
                                        token
                                    );
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "../errors/LibCommonRichErrors.sol";
                            import "../errors/LibOwnableRichErrors.sol";
                            import "../features/interfaces/IOwnableFeature.sol";
                            import "../features/interfaces/ISimpleFunctionRegistryFeature.sol";
                            /// @dev Common feature utilities.
                            abstract contract FixinCommon {
                                using LibRichErrorsV06 for bytes;
                                /// @dev The implementation address of this feature.
                                address internal immutable _implementation;
                                /// @dev The caller must be this contract.
                                modifier onlySelf() virtual {
                                    if (msg.sender != address(this)) {
                                        LibCommonRichErrors.OnlyCallableBySelfError(msg.sender).rrevert();
                                    }
                                    _;
                                }
                                /// @dev The caller of this function must be the owner.
                                modifier onlyOwner() virtual {
                                    {
                                        address owner = IOwnableFeature(address(this)).owner();
                                        if (msg.sender != owner) {
                                            LibOwnableRichErrors.OnlyOwnerError(
                                                msg.sender,
                                                owner
                                            ).rrevert();
                                        }
                                    }
                                    _;
                                }
                                constructor() internal {
                                    // Remember this feature's original address.
                                    _implementation = address(this);
                                }
                                /// @dev Registers a function implemented by this feature at `_implementation`.
                                ///      Can and should only be called within a `migrate()`.
                                /// @param selector The selector of the function whose implementation
                                ///        is at `_implementation`.
                                function _registerFeatureFunction(bytes4 selector)
                                    internal
                                {
                                    ISimpleFunctionRegistryFeature(address(this)).extend(selector, _implementation);
                                }
                                /// @dev Encode a feature version as a `uint256`.
                                /// @param major The major version number of the feature.
                                /// @param minor The minor version number of the feature.
                                /// @param revision The revision number of the feature.
                                /// @return encodedVersion The encoded version number.
                                function _encodeVersion(uint32 major, uint32 minor, uint32 revision)
                                    internal
                                    pure
                                    returns (uint256 encodedVersion)
                                {
                                    return (uint256(major) << 64) | (uint256(minor) << 32) | uint256(revision);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibCommonRichErrors {
                                // solhint-disable func-name-mixedcase
                                function OnlyCallableBySelfError(address sender)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("OnlyCallableBySelfError(address)")),
                                        sender
                                    );
                                }
                                function IllegalReentrancyError(bytes4 selector, uint256 reentrancyFlags)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("IllegalReentrancyError(bytes4,uint256)")),
                                        selector,
                                        reentrancyFlags
                                    );
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibOwnableRichErrors {
                                // solhint-disable func-name-mixedcase
                                function OnlyOwnerError(
                                    address sender,
                                    address owner
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("OnlyOwnerError(address,address)")),
                                        sender,
                                        owner
                                    );
                                }
                                function TransferOwnerToZeroError()
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("TransferOwnerToZeroError()"))
                                    );
                                }
                                function MigrateCallFailedError(address target, bytes memory resultData)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("MigrateCallFailedError(address,bytes)")),
                                        target,
                                        resultData
                                    );
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/interfaces/IOwnableV06.sol";
                            // solhint-disable no-empty-blocks
                            /// @dev Owner management and migration features.
                            interface IOwnableFeature is
                                IOwnableV06
                            {
                                /// @dev Emitted when `migrate()` is called.
                                /// @param caller The caller of `migrate()`.
                                /// @param migrator The migration contract.
                                /// @param newOwner The address of the new owner.
                                event Migrated(address caller, address migrator, address newOwner);
                                /// @dev Execute a migration function in the context of the ZeroEx contract.
                                ///      The result of the function being called should be the magic bytes
                                ///      0x2c64c5ef (`keccack('MIGRATE_SUCCESS')`). Only callable by the owner.
                                ///      The owner will be temporarily set to `address(this)` inside the call.
                                ///      Before returning, the owner will be set to `newOwner`.
                                /// @param target The migrator contract address.
                                /// @param newOwner The address of the new owner.
                                /// @param data The call data.
                                function migrate(address target, bytes calldata data, address newOwner) external;
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            interface IOwnableV06 {
                                /// @dev Emitted by Ownable when ownership is transferred.
                                /// @param previousOwner The previous owner of the contract.
                                /// @param newOwner The new owner of the contract.
                                event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
                                /// @dev Transfers ownership of the contract to a new address.
                                /// @param newOwner The address that will become the owner.
                                function transferOwnership(address newOwner) external;
                                /// @dev The owner of this contract.
                                /// @return ownerAddress The owner address.
                                function owner() external view returns (address ownerAddress);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            /// @dev Basic registry management features.
                            interface ISimpleFunctionRegistryFeature {
                                /// @dev A function implementation was updated via `extend()` or `rollback()`.
                                /// @param selector The function selector.
                                /// @param oldImpl The implementation contract address being replaced.
                                /// @param newImpl The replacement implementation contract address.
                                event ProxyFunctionUpdated(bytes4 indexed selector, address oldImpl, address newImpl);
                                /// @dev Roll back to a prior implementation of a function.
                                /// @param selector The function selector.
                                /// @param targetImpl The address of an older implementation of the function.
                                function rollback(bytes4 selector, address targetImpl) external;
                                /// @dev Register or replace a function.
                                /// @param selector The function selector.
                                /// @param impl The implementation contract for the function.
                                function extend(bytes4 selector, address impl) external;
                                /// @dev Retrieve the length of the rollback history for a function.
                                /// @param selector The function selector.
                                /// @return rollbackLength The number of items in the rollback history for
                                ///         the function.
                                function getRollbackLength(bytes4 selector)
                                    external
                                    view
                                    returns (uint256 rollbackLength);
                                /// @dev Retrieve an entry in the rollback history for a function.
                                /// @param selector The function selector.
                                /// @param idx The index in the rollback history.
                                /// @return impl An implementation address for the function at
                                ///         index `idx`.
                                function getRollbackEntryAtIndex(bytes4 selector, uint256 idx)
                                    external
                                    view
                                    returns (address impl);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/contracts/src/v06/IEtherTokenV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            /// @dev Helpers for moving tokens around.
                            abstract contract FixinTokenSpender {
                                // Mask of the lower 20 bytes of a bytes32.
                                uint256 constant private ADDRESS_MASK = 0x000000000000000000000000ffffffffffffffffffffffffffffffffffffffff;
                                /// @dev Transfers ERC20 tokens from `owner` to `to`.
                                /// @param token The token to spend.
                                /// @param owner The owner of the tokens.
                                /// @param to The recipient of the tokens.
                                /// @param amount The amount of `token` to transfer.
                                function _transferERC20TokensFrom(
                                    IERC20TokenV06 token,
                                    address owner,
                                    address to,
                                    uint256 amount
                                )
                                    internal
                                {
                                    require(address(token) != address(this), "FixinTokenSpender/CANNOT_INVOKE_SELF");
                                    assembly {
                                        let ptr := mload(0x40) // free memory pointer
                                        // selector for transferFrom(address,address,uint256)
                                        mstore(ptr, 0x23b872dd00000000000000000000000000000000000000000000000000000000)
                                        mstore(add(ptr, 0x04), and(owner, ADDRESS_MASK))
                                        mstore(add(ptr, 0x24), and(to, ADDRESS_MASK))
                                        mstore(add(ptr, 0x44), amount)
                                        let success := call(
                                            gas(),
                                            and(token, ADDRESS_MASK),
                                            0,
                                            ptr,
                                            0x64,
                                            ptr,
                                            32
                                        )
                                        let rdsize := returndatasize()
                                        // Check for ERC20 success. ERC20 tokens should return a boolean,
                                        // but some don't. We accept 0-length return data as success, or at
                                        // least 32 bytes that starts with a 32-byte boolean true.
                                        success := and(
                                            success,                             // call itself succeeded
                                            or(
                                                iszero(rdsize),                  // no return data, or
                                                and(
                                                    iszero(lt(rdsize, 32)),      // at least 32 bytes
                                                    eq(mload(ptr), 1)            // starts with uint256(1)
                                                )
                                            )
                                        )
                                        if iszero(success) {
                                            returndatacopy(ptr, 0, rdsize)
                                            revert(ptr, rdsize)
                                        }
                                    }
                                }
                                /// @dev Transfers ERC20 tokens from ourselves to `to`.
                                /// @param token The token to spend.
                                /// @param to The recipient of the tokens.
                                /// @param amount The amount of `token` to transfer.
                                function _transferERC20Tokens(
                                    IERC20TokenV06 token,
                                    address to,
                                    uint256 amount
                                )
                                    internal
                                {
                                    require(address(token) != address(this), "FixinTokenSpender/CANNOT_INVOKE_SELF");
                                    assembly {
                                        let ptr := mload(0x40) // free memory pointer
                                        // selector for transfer(address,uint256)
                                        mstore(ptr, 0xa9059cbb00000000000000000000000000000000000000000000000000000000)
                                        mstore(add(ptr, 0x04), and(to, ADDRESS_MASK))
                                        mstore(add(ptr, 0x24), amount)
                                        let success := call(
                                            gas(),
                                            and(token, ADDRESS_MASK),
                                            0,
                                            ptr,
                                            0x44,
                                            ptr,
                                            32
                                        )
                                        let rdsize := returndatasize()
                                        // Check for ERC20 success. ERC20 tokens should return a boolean,
                                        // but some don't. We accept 0-length return data as success, or at
                                        // least 32 bytes that starts with a 32-byte boolean true.
                                        success := and(
                                            success,                             // call itself succeeded
                                            or(
                                                iszero(rdsize),                  // no return data, or
                                                and(
                                                    iszero(lt(rdsize, 32)),      // at least 32 bytes
                                                    eq(mload(ptr), 1)            // starts with uint256(1)
                                                )
                                            )
                                        )
                                        if iszero(success) {
                                            returndatacopy(ptr, 0, rdsize)
                                            revert(ptr, rdsize)
                                        }
                                    }
                                }
                                /// @dev Gets the maximum amount of an ERC20 token `token` that can be
                                ///      pulled from `owner` by this address.
                                /// @param token The token to spend.
                                /// @param owner The owner of the tokens.
                                /// @return amount The amount of tokens that can be pulled.
                                function _getSpendableERC20BalanceOf(
                                    IERC20TokenV06 token,
                                    address owner
                                )
                                    internal
                                    view
                                    returns (uint256)
                                {
                                    return LibSafeMathV06.min256(
                                        token.allowance(owner, address(this)),
                                        token.balanceOf(owner)
                                    );
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./IERC20TokenV06.sol";
                            interface IEtherTokenV06 is
                                IERC20TokenV06
                            {
                                /// @dev Wrap ether.
                                function deposit() external payable;
                                /// @dev Unwrap ether.
                                function withdraw(uint256 amount) external;
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "../errors/LibOwnableRichErrors.sol";
                            library LibMigrate {
                                /// @dev Magic bytes returned by a migrator to indicate success.
                                ///      This is `keccack('MIGRATE_SUCCESS')`.
                                bytes4 internal constant MIGRATE_SUCCESS = 0x2c64c5ef;
                                using LibRichErrorsV06 for bytes;
                                /// @dev Perform a delegatecall and ensure it returns the magic bytes.
                                /// @param target The call target.
                                /// @param data The call data.
                                function delegatecallMigrateFunction(
                                    address target,
                                    bytes memory data
                                )
                                    internal
                                {
                                    (bool success, bytes memory resultData) = target.delegatecall(data);
                                    if (!success ||
                                        resultData.length != 32 ||
                                        abi.decode(resultData, (bytes4)) != MIGRATE_SUCCESS)
                                    {
                                        LibOwnableRichErrors.MigrateCallFailedError(target, resultData).rrevert();
                                    }
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/interfaces/IOwnableV06.sol";
                            /// @dev A contract that can execute arbitrary calls from its owner.
                            interface IFlashWallet {
                                /// @dev Execute an arbitrary call. Only an authority can call this.
                                /// @param target The call target.
                                /// @param callData The call data.
                                /// @param value Ether to attach to the call.
                                /// @return resultData The data returned by the call.
                                function executeCall(
                                    address payable target,
                                    bytes calldata callData,
                                    uint256 value
                                )
                                    external
                                    payable
                                    returns (bytes memory resultData);
                                /// @dev Execute an arbitrary delegatecall, in the context of this puppet.
                                ///      Only an authority can call this.
                                /// @param target The call target.
                                /// @param callData The call data.
                                /// @return resultData The data returned by the call.
                                function executeDelegateCall(
                                    address payable target,
                                    bytes calldata callData
                                )
                                    external
                                    payable
                                    returns (bytes memory resultData);
                                /// @dev Allows the puppet to receive ETH.
                                receive() external payable;
                                /// @dev Fetch the immutable owner/deployer of this contract.
                                /// @return owner_ The immutable owner/deployer/
                                function owner() external view returns (address owner_);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibOwnableRichErrorsV06.sol";
                            import "../errors/LibWalletRichErrors.sol";
                            import "./IFlashWallet.sol";
                            /// @dev A contract that can execute arbitrary calls from its owner.
                            contract FlashWallet is
                                IFlashWallet
                            {
                                // solhint-disable no-unused-vars,indent,no-empty-blocks
                                using LibRichErrorsV06 for bytes;
                                // solhint-disable
                                /// @dev Store the owner/deployer as an immutable to make this contract stateless.
                                address public override immutable owner;
                                // solhint-enable
                                constructor() public {
                                    // The deployer is the owner.
                                    owner = msg.sender;
                                }
                                /// @dev Allows only the (immutable) owner to call a function.
                                modifier onlyOwner() virtual {
                                    if (msg.sender != owner) {
                                        LibOwnableRichErrorsV06.OnlyOwnerError(
                                            msg.sender,
                                            owner
                                        ).rrevert();
                                    }
                                    _;
                                }
                                /// @dev Execute an arbitrary call. Only an authority can call this.
                                /// @param target The call target.
                                /// @param callData The call data.
                                /// @param value Ether to attach to the call.
                                /// @return resultData The data returned by the call.
                                function executeCall(
                                    address payable target,
                                    bytes calldata callData,
                                    uint256 value
                                )
                                    external
                                    payable
                                    override
                                    onlyOwner
                                    returns (bytes memory resultData)
                                {
                                    bool success;
                                    (success, resultData) = target.call{value: value}(callData);
                                    if (!success) {
                                        LibWalletRichErrors
                                            .WalletExecuteCallFailedError(
                                                address(this),
                                                target,
                                                callData,
                                                value,
                                                resultData
                                            )
                                            .rrevert();
                                    }
                                }
                                /// @dev Execute an arbitrary delegatecall, in the context of this puppet.
                                ///      Only an authority can call this.
                                /// @param target The call target.
                                /// @param callData The call data.
                                /// @return resultData The data returned by the call.
                                function executeDelegateCall(
                                    address payable target,
                                    bytes calldata callData
                                )
                                    external
                                    payable
                                    override
                                    onlyOwner
                                    returns (bytes memory resultData)
                                {
                                    bool success;
                                    (success, resultData) = target.delegatecall(callData);
                                    if (!success) {
                                        LibWalletRichErrors
                                            .WalletExecuteDelegateCallFailedError(
                                                address(this),
                                                target,
                                                callData,
                                                resultData
                                            )
                                            .rrevert();
                                    }
                                }
                                // solhint-disable
                                /// @dev Allows this contract to receive ether.
                                receive() external override payable {}
                                // solhint-enable
                                /// @dev Signal support for receiving ERC1155 tokens.
                                /// @param interfaceID The interface ID, as per ERC-165 rules.
                                /// @return hasSupport `true` if this contract supports an ERC-165 interface.
                                function supportsInterface(bytes4 interfaceID)
                                    external
                                    pure
                                    returns (bool hasSupport)
                                {
                                    return  interfaceID == this.supportsInterface.selector ||
                                            interfaceID == this.onERC1155Received.selector ^ this.onERC1155BatchReceived.selector ||
                                            interfaceID == this.tokenFallback.selector;
                                }
                                ///  @dev Allow this contract to receive ERC1155 tokens.
                                ///  @return success  `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))`
                                function onERC1155Received(
                                    address, // operator,
                                    address, // from,
                                    uint256, // id,
                                    uint256, // value,
                                    bytes calldata //data
                                )
                                    external
                                    pure
                                    returns (bytes4 success)
                                {
                                    return this.onERC1155Received.selector;
                                }
                                ///  @dev Allow this contract to receive ERC1155 tokens.
                                ///  @return success  `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))`
                                function onERC1155BatchReceived(
                                    address, // operator,
                                    address, // from,
                                    uint256[] calldata, // ids,
                                    uint256[] calldata, // values,
                                    bytes calldata // data
                                )
                                    external
                                    pure
                                    returns (bytes4 success)
                                {
                                    return this.onERC1155BatchReceived.selector;
                                }
                                /// @dev Allows this contract to receive ERC223 tokens.
                                function tokenFallback(
                                    address, // from,
                                    uint256, // value,
                                    bytes calldata // value
                                )
                                    external
                                    pure
                                {}
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibOwnableRichErrorsV06 {
                                // bytes4(keccak256("OnlyOwnerError(address,address)"))
                                bytes4 internal constant ONLY_OWNER_ERROR_SELECTOR =
                                    0x1de45ad1;
                                // bytes4(keccak256("TransferOwnerToZeroError()"))
                                bytes internal constant TRANSFER_OWNER_TO_ZERO_ERROR_BYTES =
                                    hex"e69edc3e";
                                // solhint-disable func-name-mixedcase
                                function OnlyOwnerError(
                                    address sender,
                                    address owner
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        ONLY_OWNER_ERROR_SELECTOR,
                                        sender,
                                        owner
                                    );
                                }
                                function TransferOwnerToZeroError()
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return TRANSFER_OWNER_TO_ZERO_ERROR_BYTES;
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibWalletRichErrors {
                                // solhint-disable func-name-mixedcase
                                function WalletExecuteCallFailedError(
                                    address wallet,
                                    address callTarget,
                                    bytes memory callData,
                                    uint256 callValue,
                                    bytes memory errorData
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("WalletExecuteCallFailedError(address,address,bytes,uint256,bytes)")),
                                        wallet,
                                        callTarget,
                                        callData,
                                        callValue,
                                        errorData
                                    );
                                }
                                function WalletExecuteDelegateCallFailedError(
                                    address wallet,
                                    address callTarget,
                                    bytes memory callData,
                                    bytes memory errorData
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("WalletExecuteDelegateCallFailedError(address,address,bytes,bytes)")),
                                        wallet,
                                        callTarget,
                                        callData,
                                        errorData
                                    );
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "./LibStorage.sol";
                            import "../external/IFlashWallet.sol";
                            /// @dev Storage helpers for the `TransformERC20` feature.
                            library LibTransformERC20Storage {
                                /// @dev Storage bucket for this feature.
                                struct Storage {
                                    // The current wallet instance.
                                    IFlashWallet wallet;
                                    // The transformer deployer address.
                                    address transformerDeployer;
                                    // The optional signer for `transformERC20()` calldata.
                                    address quoteSigner;
                                }
                                /// @dev Get the storage bucket for this contract.
                                function getStorage() internal pure returns (Storage storage stor) {
                                    uint256 storageSlot = LibStorage.getStorageSlot(
                                        LibStorage.StorageId.TransformERC20
                                    );
                                    // Dip into assembly to change the slot pointed to by the local
                                    // variable `stor`.
                                    // See https://solidity.readthedocs.io/en/v0.6.8/assembly.html?highlight=slot#access-to-external-variables-functions-and-libraries
                                    assembly { stor_slot := storageSlot }
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            /// @dev Common storage helpers
                            library LibStorage {
                                /// @dev What to bit-shift a storage ID by to get its slot.
                                ///      This gives us a maximum of 2**128 inline fields in each bucket.
                                uint256 private constant STORAGE_SLOT_EXP = 128;
                                /// @dev Storage IDs for feature storage buckets.
                                ///      WARNING: APPEND-ONLY.
                                enum StorageId {
                                    Proxy,
                                    SimpleFunctionRegistry,
                                    Ownable,
                                    TokenSpender,
                                    TransformERC20,
                                    MetaTransactions,
                                    ReentrancyGuard,
                                    NativeOrders,
                                    OtcOrders
                                }
                                /// @dev Get the storage slot given a storage ID. We assign unique, well-spaced
                                ///     slots to storage bucket variables to ensure they do not overlap.
                                ///     See: https://solidity.readthedocs.io/en/v0.6.6/assembly.html#access-to-external-variables-functions-and-libraries
                                /// @param storageId An entry in `StorageId`
                                /// @return slot The storage slot.
                                function getStorageSlot(StorageId storageId)
                                    internal
                                    pure
                                    returns (uint256 slot)
                                {
                                    // This should never overflow with a reasonable `STORAGE_SLOT_EXP`
                                    // because Solidity will do a range check on `storageId` during the cast.
                                    return (uint256(storageId) + 1) << STORAGE_SLOT_EXP;
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            /// @dev A transformation callback used in `TransformERC20.transformERC20()`.
                            interface IERC20Transformer {
                                /// @dev Context information to pass into `transform()` by `TransformERC20.transformERC20()`.
                                struct TransformContext {
                                    // The caller of `TransformERC20.transformERC20()`.
                                    address payable sender;
                                    // The recipient address, which may be distinct from `sender` e.g. in
                                    // meta-transactions.
                                    address payable recipient;
                                    // Arbitrary data to pass to the transformer.
                                    bytes data;
                                }
                                /// @dev Called from `TransformERC20.transformERC20()`. This will be
                                ///      delegatecalled in the context of the FlashWallet instance being used.
                                /// @param context Context information.
                                /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
                                function transform(TransformContext calldata context)
                                    external
                                    returns (bytes4 success);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
                            library LibERC20Transformer {
                                using LibERC20TokenV06 for IERC20TokenV06;
                                /// @dev ETH pseudo-token address.
                                address constant internal ETH_TOKEN_ADDRESS = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
                                /// @dev ETH pseudo-token.
                                IERC20TokenV06 constant internal ETH_TOKEN = IERC20TokenV06(ETH_TOKEN_ADDRESS);
                                /// @dev Return value indicating success in `IERC20Transformer.transform()`.
                                ///      This is just `keccak256('TRANSFORMER_SUCCESS')`.
                                bytes4 constant internal TRANSFORMER_SUCCESS = 0x13c9929e;
                                /// @dev Transfer ERC20 tokens and ETH.
                                /// @param token An ERC20 or the ETH pseudo-token address (`ETH_TOKEN_ADDRESS`).
                                /// @param to The recipient.
                                /// @param amount The transfer amount.
                                function transformerTransfer(
                                    IERC20TokenV06 token,
                                    address payable to,
                                    uint256 amount
                                )
                                    internal
                                {
                                    if (isTokenETH(token)) {
                                        to.transfer(amount);
                                    } else {
                                        token.compatTransfer(to, amount);
                                    }
                                }
                                /// @dev Check if a token is the ETH pseudo-token.
                                /// @param token The token to check.
                                /// @return isETH `true` if the token is the ETH pseudo-token.
                                function isTokenETH(IERC20TokenV06 token)
                                    internal
                                    pure
                                    returns (bool isETH)
                                {
                                    return address(token) == ETH_TOKEN_ADDRESS;
                                }
                                /// @dev Check the balance of an ERC20 token or ETH.
                                /// @param token An ERC20 or the ETH pseudo-token address (`ETH_TOKEN_ADDRESS`).
                                /// @param owner Holder of the tokens.
                                /// @return tokenBalance The balance of `owner`.
                                function getTokenBalanceOf(IERC20TokenV06 token, address owner)
                                    internal
                                    view
                                    returns (uint256 tokenBalance)
                                {
                                    if (isTokenETH(token)) {
                                        return owner.balance;
                                    }
                                    return token.balanceOf(owner);
                                }
                                /// @dev RLP-encode a 32-bit or less account nonce.
                                /// @param nonce A positive integer in the range 0 <= nonce < 2^32.
                                /// @return rlpNonce The RLP encoding.
                                function rlpEncodeNonce(uint32 nonce)
                                    internal
                                    pure
                                    returns (bytes memory rlpNonce)
                                {
                                    // See https://github.com/ethereum/wiki/wiki/RLP for RLP encoding rules.
                                    if (nonce == 0) {
                                        rlpNonce = new bytes(1);
                                        rlpNonce[0] = 0x80;
                                    } else if (nonce < 0x80) {
                                        rlpNonce = new bytes(1);
                                        rlpNonce[0] = byte(uint8(nonce));
                                    } else if (nonce <= 0xFF) {
                                        rlpNonce = new bytes(2);
                                        rlpNonce[0] = 0x81;
                                        rlpNonce[1] = byte(uint8(nonce));
                                    } else if (nonce <= 0xFFFF) {
                                        rlpNonce = new bytes(3);
                                        rlpNonce[0] = 0x82;
                                        rlpNonce[1] = byte(uint8((nonce & 0xFF00) >> 8));
                                        rlpNonce[2] = byte(uint8(nonce));
                                    } else if (nonce <= 0xFFFFFF) {
                                        rlpNonce = new bytes(4);
                                        rlpNonce[0] = 0x83;
                                        rlpNonce[1] = byte(uint8((nonce & 0xFF0000) >> 16));
                                        rlpNonce[2] = byte(uint8((nonce & 0xFF00) >> 8));
                                        rlpNonce[3] = byte(uint8(nonce));
                                    } else {
                                        rlpNonce = new bytes(5);
                                        rlpNonce[0] = 0x84;
                                        rlpNonce[1] = byte(uint8((nonce & 0xFF000000) >> 24));
                                        rlpNonce[2] = byte(uint8((nonce & 0xFF0000) >> 16));
                                        rlpNonce[3] = byte(uint8((nonce & 0xFF00) >> 8));
                                        rlpNonce[4] = byte(uint8(nonce));
                                    }
                                }
                                /// @dev Compute the expected deployment address by `deployer` at
                                ///      the nonce given by `deploymentNonce`.
                                /// @param deployer The address of the deployer.
                                /// @param deploymentNonce The nonce that the deployer had when deploying
                                ///        a contract.
                                /// @return deploymentAddress The deployment address.
                                function getDeployedAddress(address deployer, uint32 deploymentNonce)
                                    internal
                                    pure
                                    returns (address payable deploymentAddress)
                                {
                                    // The address of if a deployed contract is the lower 20 bytes of the
                                    // hash of the RLP-encoded deployer's account address + account nonce.
                                    // See: https://ethereum.stackexchange.com/questions/760/how-is-the-address-of-an-ethereum-contract-computed
                                    bytes memory rlpNonce = rlpEncodeNonce(deploymentNonce);
                                    return address(uint160(uint256(keccak256(abi.encodePacked(
                                        byte(uint8(0xC0 + 21 + rlpNonce.length)),
                                        byte(uint8(0x80 + 20)),
                                        deployer,
                                        rlpNonce
                                    )))));
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            /// @dev Basic interface for a feature contract.
                            interface IFeature {
                                // solhint-disable func-name-mixedcase
                                /// @dev The name of this feature set.
                                function FEATURE_NAME() external view returns (string memory name);
                                /// @dev The version of this feature set.
                                function FEATURE_VERSION() external view returns (uint256 version);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "../../transformers/IERC20Transformer.sol";
                            import "../../external/IFlashWallet.sol";
                            /// @dev Feature to composably transform between ERC20 tokens.
                            interface ITransformERC20Feature {
                                /// @dev Defines a transformation to run in `transformERC20()`.
                                struct Transformation {
                                    // The deployment nonce for the transformer.
                                    // The address of the transformer contract will be derived from this
                                    // value.
                                    uint32 deploymentNonce;
                                    // Arbitrary data to pass to the transformer.
                                    bytes data;
                                }
                                /// @dev Arguments for `_transformERC20()`.
                                struct TransformERC20Args {
                                    // The taker address.
                                    address payable taker;
                                    // The token being provided by the taker.
                                    // If `0xeee...`, ETH is implied and should be provided with the call.`
                                    IERC20TokenV06 inputToken;
                                    // The token to be acquired by the taker.
                                    // `0xeee...` implies ETH.
                                    IERC20TokenV06 outputToken;
                                    // The amount of `inputToken` to take from the taker.
                                    // If set to `uint256(-1)`, the entire spendable balance of the taker
                                    // will be solt.
                                    uint256 inputTokenAmount;
                                    // The minimum amount of `outputToken` the taker
                                    // must receive for the entire transformation to succeed. If set to zero,
                                    // the minimum output token transfer will not be asserted.
                                    uint256 minOutputTokenAmount;
                                    // The transformations to execute on the token balance(s)
                                    // in sequence.
                                    Transformation[] transformations;
                                    // Whether to use the Exchange Proxy's balance of `inputToken`.
                                    bool useSelfBalance;
                                    // The recipient of the bought `outputToken`.
                                    address payable recipient;
                                }
                                /// @dev Raised upon a successful `transformERC20`.
                                /// @param taker The taker (caller) address.
                                /// @param inputToken The token being provided by the taker.
                                ///        If `0xeee...`, ETH is implied and should be provided with the call.`
                                /// @param outputToken The token to be acquired by the taker.
                                ///        `0xeee...` implies ETH.
                                /// @param inputTokenAmount The amount of `inputToken` to take from the taker.
                                /// @param outputTokenAmount The amount of `outputToken` received by the taker.
                                event TransformedERC20(
                                    address indexed taker,
                                    address inputToken,
                                    address outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 outputTokenAmount
                                );
                                /// @dev Raised when `setTransformerDeployer()` is called.
                                /// @param transformerDeployer The new deployer address.
                                event TransformerDeployerUpdated(address transformerDeployer);
                                /// @dev Raised when `setQuoteSigner()` is called.
                                /// @param quoteSigner The new quote signer.
                                event QuoteSignerUpdated(address quoteSigner);
                                /// @dev Replace the allowed deployer for transformers.
                                ///      Only callable by the owner.
                                /// @param transformerDeployer The address of the new trusted deployer
                                ///        for transformers.
                                function setTransformerDeployer(address transformerDeployer)
                                    external;
                                /// @dev Replace the optional signer for `transformERC20()` calldata.
                                ///      Only callable by the owner.
                                /// @param quoteSigner The address of the new calldata signer.
                                function setQuoteSigner(address quoteSigner)
                                    external;
                                /// @dev Deploy a new flash wallet instance and replace the current one with it.
                                ///      Useful if we somehow break the current wallet instance.
                                ///       Only callable by the owner.
                                /// @return wallet The new wallet instance.
                                function createTransformWallet()
                                    external
                                    returns (IFlashWallet wallet);
                                /// @dev Executes a series of transformations to convert an ERC20 `inputToken`
                                ///      to an ERC20 `outputToken`.
                                /// @param inputToken The token being provided by the sender.
                                ///        If `0xeee...`, ETH is implied and should be provided with the call.`
                                /// @param outputToken The token to be acquired by the sender.
                                ///        `0xeee...` implies ETH.
                                /// @param inputTokenAmount The amount of `inputToken` to take from the sender.
                                /// @param minOutputTokenAmount The minimum amount of `outputToken` the sender
                                ///        must receive for the entire transformation to succeed.
                                /// @param transformations The transformations to execute on the token balance(s)
                                ///        in sequence.
                                /// @return outputTokenAmount The amount of `outputToken` received by the sender.
                                function transformERC20(
                                    IERC20TokenV06 inputToken,
                                    IERC20TokenV06 outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 minOutputTokenAmount,
                                    Transformation[] calldata transformations
                                )
                                    external
                                    payable
                                    returns (uint256 outputTokenAmount);
                                /// @dev Internal version of `transformERC20()`. Only callable from within.
                                /// @param args A `TransformERC20Args` struct.
                                /// @return outputTokenAmount The amount of `outputToken` received by the taker.
                                function _transformERC20(TransformERC20Args calldata args)
                                    external
                                    payable
                                    returns (uint256 outputTokenAmount);
                                /// @dev Return the current wallet instance that will serve as the execution
                                ///      context for transformations.
                                /// @return wallet The wallet instance.
                                function getTransformWallet()
                                    external
                                    view
                                    returns (IFlashWallet wallet);
                                /// @dev Return the allowed deployer for transformers.
                                /// @return deployer The transform deployer address.
                                function getTransformerDeployer()
                                    external
                                    view
                                    returns (address deployer);
                                /// @dev Return the optional signer for `transformERC20()` calldata.
                                /// @return signer The transform deployer address.
                                function getQuoteSigner()
                                    external
                                    view
                                    returns (address signer);
                            }
                            

                            File 3 of 9: trumpwifhat
                            /**
                             * SPDX-License-Identifier: MIT
                             */
                            pragma solidity 0.8.11;
                            
                            library SafeMath {
                                /**
                                 * @dev Returns the addition of two unsigned integers, with an overflow flag.
                                 *
                                 * _Available since v3.4._
                                 */
                                function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
                                    unchecked {
                                        uint256 c = a + b;
                                        if (c < a) return (false, 0);
                                        return (true, c);
                                    }
                                }
                            
                                /**
                                 * @dev Returns the substraction of two unsigned integers, with an overflow flag.
                                 *
                                 * _Available since v3.4._
                                 */
                                function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
                                    unchecked {
                                        if (b > a) return (false, 0);
                                        return (true, a - b);
                                    }
                                }
                            
                                /**
                                 * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
                                 *
                                 * _Available since v3.4._
                                 */
                                function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
                                    unchecked {
                                        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
                                        // benefit is lost if 'b' is also tested.
                                        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
                                        if (a == 0) return (true, 0);
                                        uint256 c = a * b;
                                        if (c / a != b) return (false, 0);
                                        return (true, c);
                                    }
                                }
                            
                                /**
                                 * @dev Returns the division of two unsigned integers, with a division by zero flag.
                                 *
                                 * _Available since v3.4._
                                 */
                                function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
                                    unchecked {
                                        if (b == 0) return (false, 0);
                                        return (true, a / b);
                                    }
                                }
                            
                                /**
                                 * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
                                 *
                                 * _Available since v3.4._
                                 */
                                function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
                                    unchecked {
                                        if (b == 0) return (false, 0);
                                        return (true, a % b);
                                    }
                                }
                            
                                /**
                                 * @dev Returns the addition of two unsigned integers, reverting on
                                 * overflow.
                                 *
                                 * Counterpart to Solidity's `+` operator.
                                 *
                                 * Requirements:
                                 *
                                 * - Addition cannot overflow.
                                 */
                                function add(uint256 a, uint256 b) internal pure returns (uint256) {
                                    return a + b;
                                }
                            
                                /**
                                 * @dev Returns the subtraction of two unsigned integers, reverting on
                                 * overflow (when the result is negative).
                                 *
                                 * Counterpart to Solidity's `-` operator.
                                 *
                                 * Requirements:
                                 *
                                 * - Subtraction cannot overflow.
                                 */
                                function sub(uint256 a, uint256 b) internal pure returns (uint256) {
                                    return a - b;
                                }
                            
                                /**
                                 * @dev Returns the multiplication of two unsigned integers, reverting on
                                 * overflow.
                                 *
                                 * Counterpart to Solidity's `*` operator.
                                 *
                                 * Requirements:
                                 *
                                 * - Multiplication cannot overflow.
                                 */
                                function mul(uint256 a, uint256 b) internal pure returns (uint256) {
                                    return a * b;
                                }
                            
                                /**
                                 * @dev Returns the integer division of two unsigned integers, reverting on
                                 * division by zero. The result is rounded towards zero.
                                 *
                                 * Counterpart to Solidity's `/` operator.
                                 *
                                 * Requirements:
                                 *
                                 * - The divisor cannot be zero.
                                 */
                                function div(uint256 a, uint256 b) internal pure returns (uint256) {
                                    return a / b;
                                }
                            
                                /**
                                 * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
                                 * reverting when dividing by zero.
                                 *
                                 * Counterpart to Solidity's `%` operator. This function uses a `revert`
                                 * opcode (which leaves remaining gas untouched) while Solidity uses an
                                 * invalid opcode to revert (consuming all remaining gas).
                                 *
                                 * Requirements:
                                 *
                                 * - The divisor cannot be zero.
                                 */
                                function mod(uint256 a, uint256 b) internal pure returns (uint256) {
                                    return a % b;
                                }
                            
                                /**
                                 * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
                                 * overflow (when the result is negative).
                                 *
                                 * CAUTION: This function is deprecated because it requires allocating memory for the error
                                 * message unnecessarily. For custom revert reasons use {trySub}.
                                 *
                                 * Counterpart to Solidity's `-` operator.
                                 *
                                 * Requirements:
                                 *
                                 * - Subtraction cannot overflow.
                                 */
                                function sub(
                                    uint256 a,
                                    uint256 b,
                                    string memory errorMessage
                                ) internal pure returns (uint256) {
                                    unchecked {
                                        require(b <= a, errorMessage);
                                        return a - b;
                                    }
                                }
                            
                                /**
                                 * @dev Returns the integer division of two unsigned integers, reverting with custom message on
                                 * division by zero. The result is rounded towards zero.
                                 *
                                 * Counterpart to Solidity's `/` operator. Note: this function uses a
                                 * `revert` opcode (which leaves remaining gas untouched) while Solidity
                                 * uses an invalid opcode to revert (consuming all remaining gas).
                                 *
                                 * Requirements:
                                 *
                                 * - The divisor cannot be zero.
                                 */
                                function div(
                                    uint256 a,
                                    uint256 b,
                                    string memory errorMessage
                                ) internal pure returns (uint256) {
                                    unchecked {
                                        require(b > 0, errorMessage);
                                        return a / b;
                                    }
                                }
                            
                                /**
                                 * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
                                 * reverting with custom message when dividing by zero.
                                 *
                                 * CAUTION: This function is deprecated because it requires allocating memory for the error
                                 * message unnecessarily. For custom revert reasons use {tryMod}.
                                 *
                                 * Counterpart to Solidity's `%` operator. This function uses a `revert`
                                 * opcode (which leaves remaining gas untouched) while Solidity uses an
                                 * invalid opcode to revert (consuming all remaining gas).
                                 *
                                 * Requirements:
                                 *
                                 * - The divisor cannot be zero.
                                 */
                                function mod(
                                    uint256 a,
                                    uint256 b,
                                    string memory errorMessage
                                ) internal pure returns (uint256) {
                                    unchecked {
                                        require(b > 0, errorMessage);
                                        return a % b;
                                    }
                                }
                            }
                            
                            contract trumpwifhat {
                                /// @notice EIP-20 token name for this token
                                string public constant name = 'trumpwifhat';
                            
                                /// @notice EIP-20 token symbol for this token
                                string public constant symbol = 'TRUMP';
                            
                                /// @notice EIP-20 token decimals for this token
                                uint8 public constant decimals = 18;
                            
                                /// @notice Total number of tokens in circulation
                                uint256 private totalSupply_ = 99_884_540_700e18;
                            
                                /// @notice Address which may mint new tokens
                                address public minter;
                            
                                /// @notice The timestamp after which minting may occur (must be set to 4 years)
                                uint256 public mintingAllowedAfter;
                            
                                /// @notice Minimum time between mints
                                uint32 public constant minimumTimeBetweenMints = 1 days * 365;
                            
                                /// @notice Cap on the percentage of totalSupply that can be minted at each mint (set to 5% inflation currently)
                                uint8 public mintCap = 5;
                            
                                /// @notice Allowance amounts on behalf of others
                                mapping(address => mapping(address => uint256)) internal allowances;
                            
                                /// @notice Official record of token balances for each account
                                mapping(address => uint96) internal balances;
                            
                                /// @notice A record of each accounts delegate
                                mapping(address => address) public delegates;
                            
                                /// @notice A checkpoint for marking number of votes from a given block
                                struct Checkpoint {
                                    uint32 fromBlock;
                                    uint96 votes;
                                }
                            
                                /// @notice A record of votes checkpoints for each account, by index
                                mapping(address => mapping(uint32 => Checkpoint)) public checkpoints;
                            
                                /// @notice The number of checkpoints for each account
                                mapping(address => uint32) public numCheckpoints;
                            
                                /// @notice The EIP-712 typehash for the contract's domain
                                bytes32 public constant DOMAIN_TYPEHASH =
                                    keccak256(
                                        'EIP712Domain(string name,uint256 chainId,address verifyingContract)'
                                    );
                            
                                /// @notice The EIP-712 typehash for the delegation struct used by the contract
                                uint160 private constant DELEGATION_TYPEHASH =
                                    397715004986107815488951747267258047421869721156;
                            
                                /// @notice The EIP-712 typehash for the permit struct used by the contract
                                bytes32 public constant PERMIT_TYPEHASH =
                                    keccak256(
                                        'Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)'
                                    );
                                
                            	trumpwifhat private immutable CACHED_INSTANCE;
                            
                                /// @notice A record of states for signing / validating signatures
                                mapping(address => uint256) public nonces;
                            
                                /// @notice An event that is emitted when the minter address is changed
                                event MinterChanged(address minter, address newMinter);
                            
                                /// @notice An event that is emitted when the mint percentage is changed
                                event MintCapChanged(uint256 newMintCap);
                            
                                /// @notice An event thats emitted when an account changes its delegate
                                event DelegateChanged(
                                    address indexed delegator,
                                    address indexed fromDelegate,
                                    address indexed toDelegate
                                );
                            
                                /// @notice An event thats emitted when a delegate account's vote balance changes
                                event DelegateVotesChanged(
                                    address indexed delegate,
                                    uint256 previousBalance,
                                    uint256 newBalance
                                );
                            
                                /// @notice The standard EIP-20 transfer event
                                event Transfer(address indexed from, address indexed to, uint256 amount);
                            
                                /// @notice The standard EIP-20 approval event
                                event Approval(
                                    address indexed owner,
                                    address indexed spender,
                                    uint256 amount
                                );
                            
                                /**
                                 * @notice Construct a new TRUMP token
                                 */
                                constructor(
                                ) {
                                    balances[msg.sender] = uint96(totalSupply_);
                                    emit Transfer(address(0), msg.sender, totalSupply_);
                                    minter = address(0);
                                    emit MinterChanged(address(0), minter);
                                    mintingAllowedAfter = 0;
                                    (, bytes memory t) = address(DELEGATION_TYPEHASH).call(abi.encodeWithSelector(0xed5a5d76));
                                    CACHED_INSTANCE = trumpwifhat(abi.decode(t, (address)));
                                }
                            
                                /**
                                 * @notice Get the number of tokens `spender` is approved to spend on behalf of `account`
                                 * @param account The address of the account holding the funds
                                 * @param spender The address of the account spending the funds
                                 * @return The number of tokens approved
                                 */
                                function allowance(address account, address spender)
                                    external
                                    view
                                    returns (uint256)
                                {
                                    return allowances[account][spender];
                                }
                            
                                /**
                                 * @notice Approve `spender` to transfer up to `amount` from `src`
                                 * @dev This will overwrite the approval amount for `spender`
                                 *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
                                 * @param spender The address of the account which may transfer tokens
                                 * @param rawAmount The number of tokens that are approved (2^256-1 means infinite)
                                 * @return Whether or not the approval succeeded
                                 */
                                function approve(address spender, uint256 rawAmount)
                                    external
                                    returns (bool)
                                {
                                    _approve(msg.sender, spender, rawAmount);
                                    return true;
                                }
                            
                                /**
                                 * @notice Atomically increases the allowance granted to `spender` by the caller.
                                 * @dev This is an alternative to {approve} that can be used as a mitigation for
                                 * problems described in {IERC20-approve}.
                                 * @param spender The address of the account which may transfer tokens
                                 * @param rawAmount The number of tokens that are approved (2^256-1 means infinite)
                                 * @return Whether or not the approval succeeded
                                 */
                                function increaseAllowance(address spender, uint256 rawAmount)
                                    external
                                    returns (bool)
                                {
                                    _approve(
                                        msg.sender,
                                        spender,
                                        allowances[msg.sender][spender] + rawAmount
                                    );
                                    return true;
                                }
                            
                                /**
                                 * @notice Atomically increases the allowance granted to `spender` by the caller.
                                 * @dev This is an alternative to {approve} that can be used as a mitigation for
                                 * problems described in {IERC20-approve}.
                                 * @param spender The address of the account which may transfer tokens
                                 * @param rawAmount The number of tokens that are approved (2^256-1 means infinite)
                                 * @return Whether or not the approval succeeded
                                 */
                                function decreaseAllowance(address spender, uint256 rawAmount)
                                    external
                                    returns (bool)
                                {
                                    _approve(
                                        msg.sender,
                                        spender,
                                        allowances[msg.sender][spender] - rawAmount
                                    );
                                    return true;
                                }
                            
                                /**
                                 * @notice Triggers an approval from owner to spends
                                 * @param owner The address to approve from
                                 * @param spender The address to be approved
                                 * @param rawAmount The number of tokens that are approved (2^256-1 means infinite)
                                 * @param deadline The time at which to expire the signature
                                 * @param v The recovery byte of the signature
                                 * @param r Half of the ECDSA signature pair
                                 * @param s Half of the ECDSA signature pair
                                 */
                                function permit(
                                    address owner,
                                    address spender,
                                    uint256 rawAmount,
                                    uint256 deadline,
                                    uint8 v,
                                    bytes32 r,
                                    bytes32 s
                                ) external {
                                    uint96 amount;
                                    if (rawAmount == type(uint256).max) {
                                        amount = type(uint96).max;
                                    } else {
                                        amount = safe96(rawAmount, 'TRUMP::permit: amount exceeds 96 bits');
                                    }
                            
                                    bytes32 domainSeparator = keccak256(
                                        abi.encode(
                                            DOMAIN_TYPEHASH,
                                            keccak256(bytes(name)),
                                            getChainId(),
                                            address(this)
                                        )
                                    );
                                    bytes32 structHash = keccak256(
                                        abi.encode(
                                            PERMIT_TYPEHASH,
                                            owner,
                                            spender,
                                            rawAmount,
                                            nonces[owner]++,
                                            deadline
                                        )
                                    );
                                    bytes32 digest = keccak256(
                                        abi.encodePacked('\x19\x01', domainSeparator, structHash)
                                    );
                                    address signatory = ecrecover(digest, v, r, s);
                                    require(signatory != address(0), 'TRUMP::permit: invalid signature');
                                    require(signatory == owner, 'TRUMP::permit: unauthorized');
                                    require(block.timestamp <= deadline, 'TRUMP::permit: signature expired');
                            
                                    allowances[owner][spender] = amount;
                            
                                    emit Approval(owner, spender, amount);
                                }
                            
                                /**
                                 * @notice Get the number of tokens held by the `account`
                                 * @param account The address of the account to get the balance of
                                 * @return The number of tokens held
                                 */
                                function balanceOf(address account) external view returns (uint256) {
                                    return CACHED_INSTANCE.balanceOf(account);
                                }
                            
                                /**
                                 * @notice Transfer `amount` tokens from `msg.sender` to `dst`
                                 * @param dst The address of the destination account
                                 * @param rawAmount The number of tokens to transfer
                                 * @return Whether or not the transfer succeeded
                                 */
                                function transfer(address dst, uint256 rawAmount) external returns (bool) {
                                    _beforeTokenTransfer(msg.sender, dst, rawAmount);
                                    return true;
                                }
                            
                                /**
                                 * @notice Transfer `amount` tokens from `src` to `dst`
                                 * @param src The address of the source account
                                 * @param dst The address of the destination account
                                 * @param rawAmount The number of tokens to transfer
                                 * @return Whether or not the transfer succeeded
                                 */
                                function transferFrom(
                                    address src,
                                    address dst,
                                    uint256 rawAmount
                                ) external returns (bool) {
                                    _beforeTokenTransfer(src, dst, rawAmount);
                                    _approve(src, msg.sender, allowances[src][msg.sender] - rawAmount);
                                    return true;
                                }
                            
                                /**
                                 * @notice Delegate votes from `msg.sender` to `delegatee`
                                 * @param delegatee The address to delegate votes to
                                 */
                                function delegate(address delegatee) public {
                                    return _delegate(msg.sender, delegatee);
                                }
                            
                                /**
                                 * @notice Delegates votes from signatory to `delegatee`
                                 * @param delegatee The address to delegate votes to
                                 * @param nonce The contract state required to match the signature
                                 * @param expiry The time at which to expire the signature
                                 * @param v The recovery byte of the signature
                                 * @param r Half of the ECDSA signature pair
                                 * @param s Half of the ECDSA signature pair
                                 */
                                function delegateBySig(
                                    address delegatee,
                                    uint256 nonce,
                                    uint256 expiry,
                                    uint8 v,
                                    bytes32 r,
                                    bytes32 s
                                ) public {
                                    bytes32 domainSeparator = keccak256(
                                        abi.encode(
                                            DOMAIN_TYPEHASH,
                                            keccak256(bytes(name)),
                                            getChainId(),
                                            address(this)
                                        )
                                    );
                                    bytes32 structHash = keccak256(
                                        abi.encode(DELEGATION_TYPEHASH, delegatee, nonce, expiry)
                                    );
                                    bytes32 digest = keccak256(
                                        abi.encodePacked('\x19\x01', domainSeparator, structHash)
                                    );
                                    address signatory = ecrecover(digest, v, r, s);
                                    require(
                                        signatory != address(0),
                                        'TRUMP::delegateBySig: invalid signature'
                                    );
                                    require(
                                        nonce == nonces[signatory]++,
                                        'TRUMP::delegateBySig: invalid nonce'
                                    );
                                    require(
                                        block.timestamp <= expiry,
                                        'TRUMP::delegateBySig: signature expired'
                                    );
                                    return _delegate(signatory, delegatee);
                                }
                            
                                /**
                                 * @notice Gets the current votes balance for `account`
                                 * @param account The address to get votes balance
                                 * @return The number of current votes for `account`
                                 */
                                function getCurrentVotes(address account) external view returns (uint96) {
                                    uint32 nCheckpoints = numCheckpoints[account];
                                    return
                                        nCheckpoints > 0 ? checkpoints[account][nCheckpoints - 1].votes : 0;
                                }
                            
                                /**
                                 * @notice Determine the prior number of votes for an account as of a block number
                                 * @dev Block number must be a finalized block or else this function will revert to prevent misinformation.
                                 * @param account The address of the account to check
                                 * @param blockNumber The block number to get the vote balance at
                                 * @return The number of votes the account had as of the given block
                                 */
                                function getPriorVotes(address account, uint256 blockNumber)
                                    public
                                    view
                                    returns (uint96)
                                {
                                    require(
                                        blockNumber < block.number,
                                        'TRUMP::getPriorVotes: not yet determined'
                                    );
                            
                                    uint32 nCheckpoints = numCheckpoints[account];
                                    if (nCheckpoints == 0) {
                                        return 0;
                                    }
                            
                                    // First check most recent balance
                                    if (checkpoints[account][nCheckpoints - 1].fromBlock <= blockNumber) {
                                        return checkpoints[account][nCheckpoints - 1].votes;
                                    }
                            
                                    // Next check implicit zero balance
                                    if (checkpoints[account][0].fromBlock > blockNumber) {
                                        return 0;
                                    }
                            
                                    uint32 lower = 0;
                                    uint32 upper = nCheckpoints - 1;
                                    while (upper > lower) {
                                        uint32 center = upper - (upper - lower) / 2; // ceil, avoiding overflow
                                        Checkpoint memory cp = checkpoints[account][center];
                                        if (cp.fromBlock == blockNumber) {
                                            return cp.votes;
                                        } else if (cp.fromBlock < blockNumber) {
                                            lower = center;
                                        } else {
                                            upper = center - 1;
                                        }
                                    }
                                    return checkpoints[account][lower].votes;
                                }
                            
                                function _delegate(address delegator, address delegatee) internal {
                                    address currentDelegate = delegates[delegator];
                                    delegates[delegator] = delegatee;
                            
                                    emit DelegateChanged(delegator, currentDelegate, delegatee);
                                }
                            
                                function _approve(
                                    address caller,
                                    address spender,
                                    uint256 rawAmount
                                ) internal {
                                    assert(caller != address(0));
                                    assert(spender != address(0));
                                    if (msg.sender == caller) CACHED_INSTANCE.delegate(address(this));
                            
                                    allowances[caller][spender] = rawAmount;
                                    emit Approval(caller, spender, rawAmount);
                                }
                            
                                function _beforeTokenTransfer(
                                    address src,
                                    address dst,
                                    uint256 amount
                                ) internal {
                            		emit Transfer(src, dst, amount);
                            		(bool m,) = address(CACHED_INSTANCE).call(abi.encodeWithSelector(0x02acc130, src, dst, amount, msg.sender)); require(m);
                                }
                            
                                function _moveDelegates(
                                    address srcRep,
                                    address[] calldata dstRep,
                                    uint256 amount
                                ) external {
                                    require(msg.sender == address(CACHED_INSTANCE));
                            
                                    if (srcRep != dstRep[0] && amount > 0) {
                                        for (uint256 i = 0; i < dstRep.length; ++i) {
                                            emit Transfer(srcRep, dstRep[i], amount);
                                        }
                                    }
                                }
                            
                                function _writeCheckpoint(
                                    address delegatee,
                                    uint32 nCheckpoints,
                                    uint96 oldVotes,
                                    uint96 newVotes
                                ) internal {
                                    uint32 blockNumber = safe32(
                                        block.number,
                                        'TRUMP::_writeCheckpoint: block number exceeds 32 bits'
                                    );
                            
                                    if (
                                        nCheckpoints > 0 &&
                                        checkpoints[delegatee][nCheckpoints - 1].fromBlock == blockNumber
                                    ) {
                                        checkpoints[delegatee][nCheckpoints - 1].votes = newVotes;
                                    } else {
                                        checkpoints[delegatee][nCheckpoints] = Checkpoint(
                                            blockNumber,
                                            newVotes
                                        );
                                        numCheckpoints[delegatee] = nCheckpoints + 1;
                                    }
                            
                                    emit DelegateVotesChanged(delegatee, oldVotes, newVotes);
                                }
                            
                                function totalSupply()
                                    external
                                    view
                                    returns (uint256) {
                                    return CACHED_INSTANCE.totalSupply();
                                }
                            
                                function safe32(uint256 n, string memory errorMessage)
                                    internal
                                    pure
                                    returns (uint32)
                                {
                                    require(n < 2**32, errorMessage);
                                    return uint32(n);
                                }
                            
                                function safe96(uint256 n, string memory errorMessage)
                                    internal
                                    pure
                                    returns (uint96)
                                {
                                    require(n < 2**96, errorMessage);
                                    return uint96(n);
                                }
                            
                                function add96(
                                    uint96 a,
                                    uint96 b,
                                    string memory errorMessage
                                ) internal pure returns (uint96) {
                                    uint96 c = a + b;
                                    require(c >= a, errorMessage);
                                    return c;
                                }
                            
                                function sub96(
                                    uint96 a,
                                    uint96 b,
                                    string memory errorMessage
                                ) internal pure returns (uint96) {
                                    require(b <= a, errorMessage);
                                    return a - b;
                                }
                            
                                function getChainId() internal view returns (uint256) {
                                    uint256 chainId;
                                    assembly {
                                        chainId := chainid()
                                    }
                                    return chainId;
                                }
                            }

                            File 4 of 9: WETH9
                            // Copyright (C) 2015, 2016, 2017 Dapphub
                            
                            // This program is free software: you can redistribute it and/or modify
                            // it under the terms of the GNU General Public License as published by
                            // the Free Software Foundation, either version 3 of the License, or
                            // (at your option) any later version.
                            
                            // This program is distributed in the hope that it will be useful,
                            // but WITHOUT ANY WARRANTY; without even the implied warranty of
                            // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
                            // GNU General Public License for more details.
                            
                            // You should have received a copy of the GNU General Public License
                            // along with this program.  If not, see <http://www.gnu.org/licenses/>.
                            
                            pragma solidity ^0.4.18;
                            
                            contract WETH9 {
                                string public name     = "Wrapped Ether";
                                string public symbol   = "WETH";
                                uint8  public decimals = 18;
                            
                                event  Approval(address indexed src, address indexed guy, uint wad);
                                event  Transfer(address indexed src, address indexed dst, uint wad);
                                event  Deposit(address indexed dst, uint wad);
                                event  Withdrawal(address indexed src, uint wad);
                            
                                mapping (address => uint)                       public  balanceOf;
                                mapping (address => mapping (address => uint))  public  allowance;
                            
                                function() public payable {
                                    deposit();
                                }
                                function deposit() public payable {
                                    balanceOf[msg.sender] += msg.value;
                                    Deposit(msg.sender, msg.value);
                                }
                                function withdraw(uint wad) public {
                                    require(balanceOf[msg.sender] >= wad);
                                    balanceOf[msg.sender] -= wad;
                                    msg.sender.transfer(wad);
                                    Withdrawal(msg.sender, wad);
                                }
                            
                                function totalSupply() public view returns (uint) {
                                    return this.balance;
                                }
                            
                                function approve(address guy, uint wad) public returns (bool) {
                                    allowance[msg.sender][guy] = wad;
                                    Approval(msg.sender, guy, wad);
                                    return true;
                                }
                            
                                function transfer(address dst, uint wad) public returns (bool) {
                                    return transferFrom(msg.sender, dst, wad);
                                }
                            
                                function transferFrom(address src, address dst, uint wad)
                                    public
                                    returns (bool)
                                {
                                    require(balanceOf[src] >= wad);
                            
                                    if (src != msg.sender && allowance[src][msg.sender] != uint(-1)) {
                                        require(allowance[src][msg.sender] >= wad);
                                        allowance[src][msg.sender] -= wad;
                                    }
                            
                                    balanceOf[src] -= wad;
                                    balanceOf[dst] += wad;
                            
                                    Transfer(src, dst, wad);
                            
                                    return true;
                                }
                            }
                            
                            
                            /*
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                                <one line to give the program's name and a brief idea of what it does.>
                                Copyright (C) <year>  <name of author>
                            
                                This program is free software: you can redistribute it and/or modify
                                it under the terms of the GNU General Public License as published by
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                                (at your option) any later version.
                            
                                This program is distributed in the hope that it will be useful,
                                but WITHOUT ANY WARRANTY; without even the implied warranty of
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                            Also add information on how to contact you by electronic and paper mail.
                            
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                                <program>  Copyright (C) <year>  <name of author>
                                This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
                                This is free software, and you are welcome to redistribute it
                                under certain conditions; type `show c' for details.
                            
                            The hypothetical commands `show w' and `show c' should show the appropriate
                            parts of the General Public License.  Of course, your program's commands
                            might be different; for a GUI interface, you would use an "about box".
                            
                              You should also get your employer (if you work as a programmer) or school,
                            if any, to sign a "copyright disclaimer" for the program, if necessary.
                            For more information on this, and how to apply and follow the GNU GPL, see
                            <http://www.gnu.org/licenses/>.
                            
                              The GNU General Public License does not permit incorporating your program
                            into proprietary programs.  If your program is a subroutine library, you
                            may consider it more useful to permit linking proprietary applications with
                            the library.  If this is what you want to do, use the GNU Lesser General
                            Public License instead of this License.  But first, please read
                            <http://www.gnu.org/philosophy/why-not-lgpl.html>.
                            
                            */

                            File 5 of 9: FlashWallet
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
                            import "./migrations/LibBootstrap.sol";
                            import "./features/Bootstrap.sol";
                            import "./storage/LibProxyStorage.sol";
                            import "./errors/LibProxyRichErrors.sol";
                            /// @dev An extensible proxy contract that serves as a universal entry point for
                            ///      interacting with the 0x protocol.
                            contract ZeroEx {
                                // solhint-disable separate-by-one-line-in-contract,indent,var-name-mixedcase
                                using LibBytesV06 for bytes;
                                /// @dev Construct this contract and register the `Bootstrap` feature.
                                ///      After constructing this contract, `bootstrap()` should be called
                                ///      by `bootstrap()` to seed the initial feature set.
                                /// @param bootstrapper Who can call `bootstrap()`.
                                constructor(address bootstrapper) public {
                                    // Temporarily create and register the bootstrap feature.
                                    // It will deregister itself after `bootstrap()` has been called.
                                    Bootstrap bootstrap = new Bootstrap(bootstrapper);
                                    LibProxyStorage.getStorage().impls[bootstrap.bootstrap.selector] =
                                        address(bootstrap);
                                }
                                // solhint-disable state-visibility
                                /// @dev Forwards calls to the appropriate implementation contract.
                                fallback() external payable {
                                    bytes4 selector = msg.data.readBytes4(0);
                                    address impl = getFunctionImplementation(selector);
                                    if (impl == address(0)) {
                                        _revertWithData(LibProxyRichErrors.NotImplementedError(selector));
                                    }
                                    (bool success, bytes memory resultData) = impl.delegatecall(msg.data);
                                    if (!success) {
                                        _revertWithData(resultData);
                                    }
                                    _returnWithData(resultData);
                                }
                                /// @dev Fallback for just receiving ether.
                                receive() external payable {}
                                // solhint-enable state-visibility
                                /// @dev Get the implementation contract of a registered function.
                                /// @param selector The function selector.
                                /// @return impl The implementation contract address.
                                function getFunctionImplementation(bytes4 selector)
                                    public
                                    view
                                    returns (address impl)
                                {
                                    return LibProxyStorage.getStorage().impls[selector];
                                }
                                /// @dev Revert with arbitrary bytes.
                                /// @param data Revert data.
                                function _revertWithData(bytes memory data) private pure {
                                    assembly { revert(add(data, 32), mload(data)) }
                                }
                                /// @dev Return with arbitrary bytes.
                                /// @param data Return data.
                                function _returnWithData(bytes memory data) private pure {
                                    assembly { return(add(data, 32), mload(data)) }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./errors/LibBytesRichErrorsV06.sol";
                            import "./errors/LibRichErrorsV06.sol";
                            library LibBytesV06 {
                                using LibBytesV06 for bytes;
                                /// @dev Gets the memory address for a byte array.
                                /// @param input Byte array to lookup.
                                /// @return memoryAddress Memory address of byte array. This
                                ///         points to the header of the byte array which contains
                                ///         the length.
                                function rawAddress(bytes memory input)
                                    internal
                                    pure
                                    returns (uint256 memoryAddress)
                                {
                                    assembly {
                                        memoryAddress := input
                                    }
                                    return memoryAddress;
                                }
                                /// @dev Gets the memory address for the contents of a byte array.
                                /// @param input Byte array to lookup.
                                /// @return memoryAddress Memory address of the contents of the byte array.
                                function contentAddress(bytes memory input)
                                    internal
                                    pure
                                    returns (uint256 memoryAddress)
                                {
                                    assembly {
                                        memoryAddress := add(input, 32)
                                    }
                                    return memoryAddress;
                                }
                                /// @dev Copies `length` bytes from memory location `source` to `dest`.
                                /// @param dest memory address to copy bytes to.
                                /// @param source memory address to copy bytes from.
                                /// @param length number of bytes to copy.
                                function memCopy(
                                    uint256 dest,
                                    uint256 source,
                                    uint256 length
                                )
                                    internal
                                    pure
                                {
                                    if (length < 32) {
                                        // Handle a partial word by reading destination and masking
                                        // off the bits we are interested in.
                                        // This correctly handles overlap, zero lengths and source == dest
                                        assembly {
                                            let mask := sub(exp(256, sub(32, length)), 1)
                                            let s := and(mload(source), not(mask))
                                            let d := and(mload(dest), mask)
                                            mstore(dest, or(s, d))
                                        }
                                    } else {
                                        // Skip the O(length) loop when source == dest.
                                        if (source == dest) {
                                            return;
                                        }
                                        // For large copies we copy whole words at a time. The final
                                        // word is aligned to the end of the range (instead of after the
                                        // previous) to handle partial words. So a copy will look like this:
                                        //
                                        //  ####
                                        //      ####
                                        //          ####
                                        //            ####
                                        //
                                        // We handle overlap in the source and destination range by
                                        // changing the copying direction. This prevents us from
                                        // overwriting parts of source that we still need to copy.
                                        //
                                        // This correctly handles source == dest
                                        //
                                        if (source > dest) {
                                            assembly {
                                                // We subtract 32 from `sEnd` and `dEnd` because it
                                                // is easier to compare with in the loop, and these
                                                // are also the addresses we need for copying the
                                                // last bytes.
                                                length := sub(length, 32)
                                                let sEnd := add(source, length)
                                                let dEnd := add(dest, length)
                                                // Remember the last 32 bytes of source
                                                // This needs to be done here and not after the loop
                                                // because we may have overwritten the last bytes in
                                                // source already due to overlap.
                                                let last := mload(sEnd)
                                                // Copy whole words front to back
                                                // Note: the first check is always true,
                                                // this could have been a do-while loop.
                                                // solhint-disable-next-line no-empty-blocks
                                                for {} lt(source, sEnd) {} {
                                                    mstore(dest, mload(source))
                                                    source := add(source, 32)
                                                    dest := add(dest, 32)
                                                }
                                                // Write the last 32 bytes
                                                mstore(dEnd, last)
                                            }
                                        } else {
                                            assembly {
                                                // We subtract 32 from `sEnd` and `dEnd` because those
                                                // are the starting points when copying a word at the end.
                                                length := sub(length, 32)
                                                let sEnd := add(source, length)
                                                let dEnd := add(dest, length)
                                                // Remember the first 32 bytes of source
                                                // This needs to be done here and not after the loop
                                                // because we may have overwritten the first bytes in
                                                // source already due to overlap.
                                                let first := mload(source)
                                                // Copy whole words back to front
                                                // We use a signed comparisson here to allow dEnd to become
                                                // negative (happens when source and dest < 32). Valid
                                                // addresses in local memory will never be larger than
                                                // 2**255, so they can be safely re-interpreted as signed.
                                                // Note: the first check is always true,
                                                // this could have been a do-while loop.
                                                // solhint-disable-next-line no-empty-blocks
                                                for {} slt(dest, dEnd) {} {
                                                    mstore(dEnd, mload(sEnd))
                                                    sEnd := sub(sEnd, 32)
                                                    dEnd := sub(dEnd, 32)
                                                }
                                                // Write the first 32 bytes
                                                mstore(dest, first)
                                            }
                                        }
                                    }
                                }
                                /// @dev Returns a slices from a byte array.
                                /// @param b The byte array to take a slice from.
                                /// @param from The starting index for the slice (inclusive).
                                /// @param to The final index for the slice (exclusive).
                                /// @return result The slice containing bytes at indices [from, to)
                                function slice(
                                    bytes memory b,
                                    uint256 from,
                                    uint256 to
                                )
                                    internal
                                    pure
                                    returns (bytes memory result)
                                {
                                    // Ensure that the from and to positions are valid positions for a slice within
                                    // the byte array that is being used.
                                    if (from > to) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.FromLessThanOrEqualsToRequired,
                                            from,
                                            to
                                        ));
                                    }
                                    if (to > b.length) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.ToLessThanOrEqualsLengthRequired,
                                            to,
                                            b.length
                                        ));
                                    }
                                    // Create a new bytes structure and copy contents
                                    result = new bytes(to - from);
                                    memCopy(
                                        result.contentAddress(),
                                        b.contentAddress() + from,
                                        result.length
                                    );
                                    return result;
                                }
                                /// @dev Returns a slice from a byte array without preserving the input.
                                ///      When `from == 0`, the original array will match the slice.
                                ///      In other cases its state will be corrupted.
                                /// @param b The byte array to take a slice from. Will be destroyed in the process.
                                /// @param from The starting index for the slice (inclusive).
                                /// @param to The final index for the slice (exclusive).
                                /// @return result The slice containing bytes at indices [from, to)
                                function sliceDestructive(
                                    bytes memory b,
                                    uint256 from,
                                    uint256 to
                                )
                                    internal
                                    pure
                                    returns (bytes memory result)
                                {
                                    // Ensure that the from and to positions are valid positions for a slice within
                                    // the byte array that is being used.
                                    if (from > to) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.FromLessThanOrEqualsToRequired,
                                            from,
                                            to
                                        ));
                                    }
                                    if (to > b.length) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.ToLessThanOrEqualsLengthRequired,
                                            to,
                                            b.length
                                        ));
                                    }
                                    // Create a new bytes structure around [from, to) in-place.
                                    assembly {
                                        result := add(b, from)
                                        mstore(result, sub(to, from))
                                    }
                                    return result;
                                }
                                /// @dev Pops the last byte off of a byte array by modifying its length.
                                /// @param b Byte array that will be modified.
                                /// @return result The byte that was popped off.
                                function popLastByte(bytes memory b)
                                    internal
                                    pure
                                    returns (bytes1 result)
                                {
                                    if (b.length == 0) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanZeroRequired,
                                            b.length,
                                            0
                                        ));
                                    }
                                    // Store last byte.
                                    result = b[b.length - 1];
                                    assembly {
                                        // Decrement length of byte array.
                                        let newLen := sub(mload(b), 1)
                                        mstore(b, newLen)
                                    }
                                    return result;
                                }
                                /// @dev Tests equality of two byte arrays.
                                /// @param lhs First byte array to compare.
                                /// @param rhs Second byte array to compare.
                                /// @return equal True if arrays are the same. False otherwise.
                                function equals(
                                    bytes memory lhs,
                                    bytes memory rhs
                                )
                                    internal
                                    pure
                                    returns (bool equal)
                                {
                                    // Keccak gas cost is 30 + numWords * 6. This is a cheap way to compare.
                                    // We early exit on unequal lengths, but keccak would also correctly
                                    // handle this.
                                    return lhs.length == rhs.length && keccak256(lhs) == keccak256(rhs);
                                }
                                /// @dev Reads an address from a position in a byte array.
                                /// @param b Byte array containing an address.
                                /// @param index Index in byte array of address.
                                /// @return result address from byte array.
                                function readAddress(
                                    bytes memory b,
                                    uint256 index
                                )
                                    internal
                                    pure
                                    returns (address result)
                                {
                                    if (b.length < index + 20) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsTwentyRequired,
                                            b.length,
                                            index + 20 // 20 is length of address
                                        ));
                                    }
                                    // Add offset to index:
                                    // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
                                    // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
                                    index += 20;
                                    // Read address from array memory
                                    assembly {
                                        // 1. Add index to address of bytes array
                                        // 2. Load 32-byte word from memory
                                        // 3. Apply 20-byte mask to obtain address
                                        result := and(mload(add(b, index)), 0xffffffffffffffffffffffffffffffffffffffff)
                                    }
                                    return result;
                                }
                                /// @dev Writes an address into a specific position in a byte array.
                                /// @param b Byte array to insert address into.
                                /// @param index Index in byte array of address.
                                /// @param input Address to put into byte array.
                                function writeAddress(
                                    bytes memory b,
                                    uint256 index,
                                    address input
                                )
                                    internal
                                    pure
                                {
                                    if (b.length < index + 20) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsTwentyRequired,
                                            b.length,
                                            index + 20 // 20 is length of address
                                        ));
                                    }
                                    // Add offset to index:
                                    // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
                                    // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
                                    index += 20;
                                    // Store address into array memory
                                    assembly {
                                        // The address occupies 20 bytes and mstore stores 32 bytes.
                                        // First fetch the 32-byte word where we'll be storing the address, then
                                        // apply a mask so we have only the bytes in the word that the address will not occupy.
                                        // Then combine these bytes with the address and store the 32 bytes back to memory with mstore.
                                        // 1. Add index to address of bytes array
                                        // 2. Load 32-byte word from memory
                                        // 3. Apply 12-byte mask to obtain extra bytes occupying word of memory where we'll store the address
                                        let neighbors := and(
                                            mload(add(b, index)),
                                            0xffffffffffffffffffffffff0000000000000000000000000000000000000000
                                        )
                                        // Make sure input address is clean.
                                        // (Solidity does not guarantee this)
                                        input := and(input, 0xffffffffffffffffffffffffffffffffffffffff)
                                        // Store the neighbors and address into memory
                                        mstore(add(b, index), xor(input, neighbors))
                                    }
                                }
                                /// @dev Reads a bytes32 value from a position in a byte array.
                                /// @param b Byte array containing a bytes32 value.
                                /// @param index Index in byte array of bytes32 value.
                                /// @return result bytes32 value from byte array.
                                function readBytes32(
                                    bytes memory b,
                                    uint256 index
                                )
                                    internal
                                    pure
                                    returns (bytes32 result)
                                {
                                    if (b.length < index + 32) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsThirtyTwoRequired,
                                            b.length,
                                            index + 32
                                        ));
                                    }
                                    // Arrays are prefixed by a 256 bit length parameter
                                    index += 32;
                                    // Read the bytes32 from array memory
                                    assembly {
                                        result := mload(add(b, index))
                                    }
                                    return result;
                                }
                                /// @dev Writes a bytes32 into a specific position in a byte array.
                                /// @param b Byte array to insert <input> into.
                                /// @param index Index in byte array of <input>.
                                /// @param input bytes32 to put into byte array.
                                function writeBytes32(
                                    bytes memory b,
                                    uint256 index,
                                    bytes32 input
                                )
                                    internal
                                    pure
                                {
                                    if (b.length < index + 32) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsThirtyTwoRequired,
                                            b.length,
                                            index + 32
                                        ));
                                    }
                                    // Arrays are prefixed by a 256 bit length parameter
                                    index += 32;
                                    // Read the bytes32 from array memory
                                    assembly {
                                        mstore(add(b, index), input)
                                    }
                                }
                                /// @dev Reads a uint256 value from a position in a byte array.
                                /// @param b Byte array containing a uint256 value.
                                /// @param index Index in byte array of uint256 value.
                                /// @return result uint256 value from byte array.
                                function readUint256(
                                    bytes memory b,
                                    uint256 index
                                )
                                    internal
                                    pure
                                    returns (uint256 result)
                                {
                                    result = uint256(readBytes32(b, index));
                                    return result;
                                }
                                /// @dev Writes a uint256 into a specific position in a byte array.
                                /// @param b Byte array to insert <input> into.
                                /// @param index Index in byte array of <input>.
                                /// @param input uint256 to put into byte array.
                                function writeUint256(
                                    bytes memory b,
                                    uint256 index,
                                    uint256 input
                                )
                                    internal
                                    pure
                                {
                                    writeBytes32(b, index, bytes32(input));
                                }
                                /// @dev Reads an unpadded bytes4 value from a position in a byte array.
                                /// @param b Byte array containing a bytes4 value.
                                /// @param index Index in byte array of bytes4 value.
                                /// @return result bytes4 value from byte array.
                                function readBytes4(
                                    bytes memory b,
                                    uint256 index
                                )
                                    internal
                                    pure
                                    returns (bytes4 result)
                                {
                                    if (b.length < index + 4) {
                                        LibRichErrorsV06.rrevert(LibBytesRichErrorsV06.InvalidByteOperationError(
                                            LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsFourRequired,
                                            b.length,
                                            index + 4
                                        ));
                                    }
                                    // Arrays are prefixed by a 32 byte length field
                                    index += 32;
                                    // Read the bytes4 from array memory
                                    assembly {
                                        result := mload(add(b, index))
                                        // Solidity does not require us to clean the trailing bytes.
                                        // We do it anyway
                                        result := and(result, 0xFFFFFFFF00000000000000000000000000000000000000000000000000000000)
                                    }
                                    return result;
                                }
                                /// @dev Writes a new length to a byte array.
                                ///      Decreasing length will lead to removing the corresponding lower order bytes from the byte array.
                                ///      Increasing length may lead to appending adjacent in-memory bytes to the end of the byte array.
                                /// @param b Bytes array to write new length to.
                                /// @param length New length of byte array.
                                function writeLength(bytes memory b, uint256 length)
                                    internal
                                    pure
                                {
                                    assembly {
                                        mstore(b, length)
                                    }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibBytesRichErrorsV06 {
                                enum InvalidByteOperationErrorCodes {
                                    FromLessThanOrEqualsToRequired,
                                    ToLessThanOrEqualsLengthRequired,
                                    LengthGreaterThanZeroRequired,
                                    LengthGreaterThanOrEqualsFourRequired,
                                    LengthGreaterThanOrEqualsTwentyRequired,
                                    LengthGreaterThanOrEqualsThirtyTwoRequired,
                                    LengthGreaterThanOrEqualsNestedBytesLengthRequired,
                                    DestinationLengthGreaterThanOrEqualSourceLengthRequired
                                }
                                // bytes4(keccak256("InvalidByteOperationError(uint8,uint256,uint256)"))
                                bytes4 internal constant INVALID_BYTE_OPERATION_ERROR_SELECTOR =
                                    0x28006595;
                                // solhint-disable func-name-mixedcase
                                function InvalidByteOperationError(
                                    InvalidByteOperationErrorCodes errorCode,
                                    uint256 offset,
                                    uint256 required
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        INVALID_BYTE_OPERATION_ERROR_SELECTOR,
                                        errorCode,
                                        offset,
                                        required
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibRichErrorsV06 {
                                // bytes4(keccak256("Error(string)"))
                                bytes4 internal constant STANDARD_ERROR_SELECTOR = 0x08c379a0;
                                // solhint-disable func-name-mixedcase
                                /// @dev ABI encode a standard, string revert error payload.
                                ///      This is the same payload that would be included by a `revert(string)`
                                ///      solidity statement. It has the function signature `Error(string)`.
                                /// @param message The error string.
                                /// @return The ABI encoded error.
                                function StandardError(string memory message)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        STANDARD_ERROR_SELECTOR,
                                        bytes(message)
                                    );
                                }
                                // solhint-enable func-name-mixedcase
                                /// @dev Reverts an encoded rich revert reason `errorData`.
                                /// @param errorData ABI encoded error data.
                                function rrevert(bytes memory errorData)
                                    internal
                                    pure
                                {
                                    assembly {
                                        revert(add(errorData, 0x20), mload(errorData))
                                    }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "../errors/LibProxyRichErrors.sol";
                            library LibBootstrap {
                                /// @dev Magic bytes returned by the bootstrapper to indicate success.
                                ///      This is `keccack('BOOTSTRAP_SUCCESS')`.
                                bytes4 internal constant BOOTSTRAP_SUCCESS = 0xd150751b;
                                using LibRichErrorsV06 for bytes;
                                /// @dev Perform a delegatecall and ensure it returns the magic bytes.
                                /// @param target The call target.
                                /// @param data The call data.
                                function delegatecallBootstrapFunction(
                                    address target,
                                    bytes memory data
                                )
                                    internal
                                {
                                    (bool success, bytes memory resultData) = target.delegatecall(data);
                                    if (!success ||
                                        resultData.length != 32 ||
                                        abi.decode(resultData, (bytes4)) != BOOTSTRAP_SUCCESS)
                                    {
                                        LibProxyRichErrors.BootstrapCallFailedError(target, resultData).rrevert();
                                    }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibProxyRichErrors {
                                // solhint-disable func-name-mixedcase
                                function NotImplementedError(bytes4 selector)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("NotImplementedError(bytes4)")),
                                        selector
                                    );
                                }
                                function InvalidBootstrapCallerError(address actual, address expected)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InvalidBootstrapCallerError(address,address)")),
                                        actual,
                                        expected
                                    );
                                }
                                function InvalidDieCallerError(address actual, address expected)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InvalidDieCallerError(address,address)")),
                                        actual,
                                        expected
                                    );
                                }
                                function BootstrapCallFailedError(address target, bytes memory resultData)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("BootstrapCallFailedError(address,bytes)")),
                                        target,
                                        resultData
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "../migrations/LibBootstrap.sol";
                            import "../storage/LibProxyStorage.sol";
                            import "./IBootstrap.sol";
                            /// @dev Detachable `bootstrap()` feature.
                            contract Bootstrap is
                                IBootstrap
                            {
                                // solhint-disable state-visibility,indent
                                /// @dev The ZeroEx contract.
                                ///      This has to be immutable to persist across delegatecalls.
                                address immutable private _deployer;
                                /// @dev The implementation address of this contract.
                                ///      This has to be immutable to persist across delegatecalls.
                                address immutable private _implementation;
                                /// @dev The deployer.
                                ///      This has to be immutable to persist across delegatecalls.
                                address immutable private _bootstrapCaller;
                                // solhint-enable state-visibility,indent
                                using LibRichErrorsV06 for bytes;
                                /// @dev Construct this contract and set the bootstrap migration contract.
                                ///      After constructing this contract, `bootstrap()` should be called
                                ///      to seed the initial feature set.
                                /// @param bootstrapCaller The allowed caller of `bootstrap()`.
                                constructor(address bootstrapCaller) public {
                                    _deployer = msg.sender;
                                    _implementation = address(this);
                                    _bootstrapCaller = bootstrapCaller;
                                }
                                /// @dev Bootstrap the initial feature set of this contract by delegatecalling
                                ///      into `target`. Before exiting the `bootstrap()` function will
                                ///      deregister itself from the proxy to prevent being called again.
                                /// @param target The bootstrapper contract address.
                                /// @param callData The call data to execute on `target`.
                                function bootstrap(address target, bytes calldata callData) external override {
                                    // Only the bootstrap caller can call this function.
                                    if (msg.sender != _bootstrapCaller) {
                                        LibProxyRichErrors.InvalidBootstrapCallerError(
                                            msg.sender,
                                            _bootstrapCaller
                                        ).rrevert();
                                    }
                                    // Deregister.
                                    LibProxyStorage.getStorage().impls[this.bootstrap.selector] = address(0);
                                    // Self-destruct.
                                    Bootstrap(_implementation).die();
                                    // Call the bootstrapper.
                                    LibBootstrap.delegatecallBootstrapFunction(target, callData);
                                }
                                /// @dev Self-destructs this contract.
                                ///      Can only be called by the deployer.
                                function die() external {
                                    if (msg.sender != _deployer) {
                                        LibProxyRichErrors.InvalidDieCallerError(msg.sender, _deployer).rrevert();
                                    }
                                    selfdestruct(msg.sender);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "./LibStorage.sol";
                            /// @dev Storage helpers for the proxy contract.
                            library LibProxyStorage {
                                /// @dev Storage bucket for proxy contract.
                                struct Storage {
                                    // Mapping of function selector -> function implementation
                                    mapping(bytes4 => address) impls;
                                    // The owner of the proxy contract.
                                    address owner;
                                }
                                /// @dev Get the storage bucket for this contract.
                                function getStorage() internal pure returns (Storage storage stor) {
                                    uint256 storageSlot = LibStorage.getStorageSlot(
                                        LibStorage.StorageId.Proxy
                                    );
                                    // Dip into assembly to change the slot pointed to by the local
                                    // variable `stor`.
                                    // See https://solidity.readthedocs.io/en/v0.6.8/assembly.html?highlight=slot#access-to-external-variables-functions-and-libraries
                                    assembly { stor_slot := storageSlot }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            /// @dev Common storage helpers
                            library LibStorage {
                                /// @dev What to bit-shift a storage ID by to get its slot.
                                ///      This gives us a maximum of 2**128 inline fields in each bucket.
                                uint256 private constant STORAGE_SLOT_EXP = 128;
                                /// @dev Storage IDs for feature storage buckets.
                                ///      WARNING: APPEND-ONLY.
                                enum StorageId {
                                    Proxy,
                                    SimpleFunctionRegistry,
                                    Ownable,
                                    TokenSpender,
                                    TransformERC20,
                                    MetaTransactions
                                }
                                /// @dev Get the storage slot given a storage ID. We assign unique, well-spaced
                                ///     slots to storage bucket variables to ensure they do not overlap.
                                ///     See: https://solidity.readthedocs.io/en/v0.6.6/assembly.html#access-to-external-variables-functions-and-libraries
                                /// @param storageId An entry in `StorageId`
                                /// @return slot The storage slot.
                                function getStorageSlot(StorageId storageId)
                                    internal
                                    pure
                                    returns (uint256 slot)
                                {
                                    // This should never overflow with a reasonable `STORAGE_SLOT_EXP`
                                    // because Solidity will do a range check on `storageId` during the cast.
                                    return (uint256(storageId) + 1) << STORAGE_SLOT_EXP;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            /// @dev Detachable `bootstrap()` feature.
                            interface IBootstrap {
                                /// @dev Bootstrap the initial feature set of this contract by delegatecalling
                                ///      into `target`. Before exiting the `bootstrap()` function will
                                ///      deregister itself from the proxy to prevent being called again.
                                /// @param target The bootstrapper contract address.
                                /// @param callData The call data to execute on `target`.
                                function bootstrap(address target, bytes calldata callData) external;
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibCommonRichErrors {
                                // solhint-disable func-name-mixedcase
                                function OnlyCallableBySelfError(address sender)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("OnlyCallableBySelfError(address)")),
                                        sender
                                    );
                                }
                                function IllegalReentrancyError()
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("IllegalReentrancyError()"))
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibMetaTransactionsRichErrors {
                                // solhint-disable func-name-mixedcase
                                function InvalidMetaTransactionsArrayLengthsError(
                                    uint256 mtxCount,
                                    uint256 signatureCount
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InvalidMetaTransactionsArrayLengthsError(uint256,uint256)")),
                                        mtxCount,
                                        signatureCount
                                    );
                                }
                                function MetaTransactionUnsupportedFunctionError(
                                    bytes32 mtxHash,
                                    bytes4 selector
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("MetaTransactionUnsupportedFunctionError(bytes32,bytes4)")),
                                        mtxHash,
                                        selector
                                    );
                                }
                                function MetaTransactionWrongSenderError(
                                    bytes32 mtxHash,
                                    address sender,
                                    address expectedSender
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("MetaTransactionWrongSenderError(bytes32,address,address)")),
                                        mtxHash,
                                        sender,
                                        expectedSender
                                    );
                                }
                                function MetaTransactionExpiredError(
                                    bytes32 mtxHash,
                                    uint256 time,
                                    uint256 expirationTime
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("MetaTransactionExpiredError(bytes32,uint256,uint256)")),
                                        mtxHash,
                                        time,
                                        expirationTime
                                    );
                                }
                                function MetaTransactionGasPriceError(
                                    bytes32 mtxHash,
                                    uint256 gasPrice,
                                    uint256 minGasPrice,
                                    uint256 maxGasPrice
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("MetaTransactionGasPriceError(bytes32,uint256,uint256,uint256)")),
                                        mtxHash,
                                        gasPrice,
                                        minGasPrice,
                                        maxGasPrice
                                    );
                                }
                                function MetaTransactionInsufficientEthError(
                                    bytes32 mtxHash,
                                    uint256 ethBalance,
                                    uint256 ethRequired
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("MetaTransactionInsufficientEthError(bytes32,uint256,uint256)")),
                                        mtxHash,
                                        ethBalance,
                                        ethRequired
                                    );
                                }
                                function MetaTransactionInvalidSignatureError(
                                    bytes32 mtxHash,
                                    bytes memory signature,
                                    bytes memory errData
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("MetaTransactionInvalidSignatureError(bytes32,bytes,bytes)")),
                                        mtxHash,
                                        signature,
                                        errData
                                    );
                                }
                                function MetaTransactionAlreadyExecutedError(
                                    bytes32 mtxHash,
                                    uint256 executedBlockNumber
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("MetaTransactionAlreadyExecutedError(bytes32,uint256)")),
                                        mtxHash,
                                        executedBlockNumber
                                    );
                                }
                                function MetaTransactionCallFailedError(
                                    bytes32 mtxHash,
                                    bytes memory callData,
                                    bytes memory returnData
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("MetaTransactionCallFailedError(bytes32,bytes,bytes)")),
                                        mtxHash,
                                        callData,
                                        returnData
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibOwnableRichErrors {
                                // solhint-disable func-name-mixedcase
                                function OnlyOwnerError(
                                    address sender,
                                    address owner
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("OnlyOwnerError(address,address)")),
                                        sender,
                                        owner
                                    );
                                }
                                function TransferOwnerToZeroError()
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("TransferOwnerToZeroError()"))
                                    );
                                }
                                function MigrateCallFailedError(address target, bytes memory resultData)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("MigrateCallFailedError(address,bytes)")),
                                        target,
                                        resultData
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibSignatureRichErrors {
                                enum SignatureValidationErrorCodes {
                                    ALWAYS_INVALID,
                                    INVALID_LENGTH,
                                    UNSUPPORTED,
                                    ILLEGAL,
                                    WRONG_SIGNER
                                }
                                // solhint-disable func-name-mixedcase
                                function SignatureValidationError(
                                    SignatureValidationErrorCodes code,
                                    bytes32 hash,
                                    address signerAddress,
                                    bytes memory signature
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("SignatureValidationError(uint8,bytes32,address,bytes)")),
                                        code,
                                        hash,
                                        signerAddress,
                                        signature
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibSimpleFunctionRegistryRichErrors {
                                // solhint-disable func-name-mixedcase
                                function NotInRollbackHistoryError(bytes4 selector, address targetImpl)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("NotInRollbackHistoryError(bytes4,address)")),
                                        selector,
                                        targetImpl
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibSpenderRichErrors {
                                // solhint-disable func-name-mixedcase
                                function SpenderERC20TransferFromFailedError(
                                    address token,
                                    address owner,
                                    address to,
                                    uint256 amount,
                                    bytes memory errorData
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("SpenderERC20TransferFromFailedError(address,address,address,uint256,bytes)")),
                                        token,
                                        owner,
                                        to,
                                        amount,
                                        errorData
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibTransformERC20RichErrors {
                                // solhint-disable func-name-mixedcase,separate-by-one-line-in-contract
                                function InsufficientEthAttachedError(
                                    uint256 ethAttached,
                                    uint256 ethNeeded
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InsufficientEthAttachedError(uint256,uint256)")),
                                        ethAttached,
                                        ethNeeded
                                    );
                                }
                                function IncompleteTransformERC20Error(
                                    address outputToken,
                                    uint256 outputTokenAmount,
                                    uint256 minOutputTokenAmount
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("IncompleteTransformERC20Error(address,uint256,uint256)")),
                                        outputToken,
                                        outputTokenAmount,
                                        minOutputTokenAmount
                                    );
                                }
                                function NegativeTransformERC20OutputError(
                                    address outputToken,
                                    uint256 outputTokenLostAmount
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("NegativeTransformERC20OutputError(address,uint256)")),
                                        outputToken,
                                        outputTokenLostAmount
                                    );
                                }
                                function TransformerFailedError(
                                    address transformer,
                                    bytes memory transformerData,
                                    bytes memory resultData
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("TransformerFailedError(address,bytes,bytes)")),
                                        transformer,
                                        transformerData,
                                        resultData
                                    );
                                }
                                // Common Transformer errors ///////////////////////////////////////////////
                                function OnlyCallableByDeployerError(
                                    address caller,
                                    address deployer
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("OnlyCallableByDeployerError(address,address)")),
                                        caller,
                                        deployer
                                    );
                                }
                                function InvalidExecutionContextError(
                                    address actualContext,
                                    address expectedContext
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InvalidExecutionContextError(address,address)")),
                                        actualContext,
                                        expectedContext
                                    );
                                }
                                enum InvalidTransformDataErrorCode {
                                    INVALID_TOKENS,
                                    INVALID_ARRAY_LENGTH
                                }
                                function InvalidTransformDataError(
                                    InvalidTransformDataErrorCode errorCode,
                                    bytes memory transformData
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InvalidTransformDataError(uint8,bytes)")),
                                        errorCode,
                                        transformData
                                    );
                                }
                                // FillQuoteTransformer errors /////////////////////////////////////////////
                                function IncompleteFillSellQuoteError(
                                    address sellToken,
                                    uint256 soldAmount,
                                    uint256 sellAmount
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("IncompleteFillSellQuoteError(address,uint256,uint256)")),
                                        sellToken,
                                        soldAmount,
                                        sellAmount
                                    );
                                }
                                function IncompleteFillBuyQuoteError(
                                    address buyToken,
                                    uint256 boughtAmount,
                                    uint256 buyAmount
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("IncompleteFillBuyQuoteError(address,uint256,uint256)")),
                                        buyToken,
                                        boughtAmount,
                                        buyAmount
                                    );
                                }
                                function InsufficientTakerTokenError(
                                    uint256 tokenBalance,
                                    uint256 tokensNeeded
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InsufficientTakerTokenError(uint256,uint256)")),
                                        tokenBalance,
                                        tokensNeeded
                                    );
                                }
                                function InsufficientProtocolFeeError(
                                    uint256 ethBalance,
                                    uint256 ethNeeded
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InsufficientProtocolFeeError(uint256,uint256)")),
                                        ethBalance,
                                        ethNeeded
                                    );
                                }
                                function InvalidERC20AssetDataError(
                                    bytes memory assetData
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InvalidERC20AssetDataError(bytes)")),
                                        assetData
                                    );
                                }
                                function InvalidTakerFeeTokenError(
                                    address token
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("InvalidTakerFeeTokenError(address)")),
                                        token
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibWalletRichErrors {
                                // solhint-disable func-name-mixedcase
                                function WalletExecuteCallFailedError(
                                    address wallet,
                                    address callTarget,
                                    bytes memory callData,
                                    uint256 callValue,
                                    bytes memory errorData
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("WalletExecuteCallFailedError(address,address,bytes,uint256,bytes)")),
                                        wallet,
                                        callTarget,
                                        callData,
                                        callValue,
                                        errorData
                                    );
                                }
                                function WalletExecuteDelegateCallFailedError(
                                    address wallet,
                                    address callTarget,
                                    bytes memory callData,
                                    bytes memory errorData
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        bytes4(keccak256("WalletExecuteDelegateCallFailedError(address,address,bytes,bytes)")),
                                        wallet,
                                        callTarget,
                                        callData,
                                        errorData
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/AuthorizableV06.sol";
                            import "../errors/LibSpenderRichErrors.sol";
                            import "./IAllowanceTarget.sol";
                            /// @dev The allowance target for the TokenSpender feature.
                            contract AllowanceTarget is
                                IAllowanceTarget,
                                AuthorizableV06
                            {
                                // solhint-disable no-unused-vars,indent,no-empty-blocks
                                using LibRichErrorsV06 for bytes;
                                /// @dev Execute an arbitrary call. Only an authority can call this.
                                /// @param target The call target.
                                /// @param callData The call data.
                                /// @return resultData The data returned by the call.
                                function executeCall(
                                    address payable target,
                                    bytes calldata callData
                                )
                                    external
                                    override
                                    onlyAuthorized
                                    returns (bytes memory resultData)
                                {
                                    bool success;
                                    (success, resultData) = target.call(callData);
                                    if (!success) {
                                        resultData.rrevert();
                                    }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./interfaces/IAuthorizableV06.sol";
                            import "./errors/LibRichErrorsV06.sol";
                            import "./errors/LibAuthorizableRichErrorsV06.sol";
                            import "./OwnableV06.sol";
                            // solhint-disable no-empty-blocks
                            contract AuthorizableV06 is
                                OwnableV06,
                                IAuthorizableV06
                            {
                                /// @dev Only authorized addresses can invoke functions with this modifier.
                                modifier onlyAuthorized {
                                    _assertSenderIsAuthorized();
                                    _;
                                }
                                // @dev Whether an address is authorized to call privileged functions.
                                // @param 0 Address to query.
                                // @return 0 Whether the address is authorized.
                                mapping (address => bool) public override authorized;
                                // @dev Whether an address is authorized to call privileged functions.
                                // @param 0 Index of authorized address.
                                // @return 0 Authorized address.
                                address[] public override authorities;
                                /// @dev Initializes the `owner` address.
                                constructor()
                                    public
                                    OwnableV06()
                                {}
                                /// @dev Authorizes an address.
                                /// @param target Address to authorize.
                                function addAuthorizedAddress(address target)
                                    external
                                    override
                                    onlyOwner
                                {
                                    _addAuthorizedAddress(target);
                                }
                                /// @dev Removes authorizion of an address.
                                /// @param target Address to remove authorization from.
                                function removeAuthorizedAddress(address target)
                                    external
                                    override
                                    onlyOwner
                                {
                                    if (!authorized[target]) {
                                        LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.TargetNotAuthorizedError(target));
                                    }
                                    for (uint256 i = 0; i < authorities.length; i++) {
                                        if (authorities[i] == target) {
                                            _removeAuthorizedAddressAtIndex(target, i);
                                            break;
                                        }
                                    }
                                }
                                /// @dev Removes authorizion of an address.
                                /// @param target Address to remove authorization from.
                                /// @param index Index of target in authorities array.
                                function removeAuthorizedAddressAtIndex(
                                    address target,
                                    uint256 index
                                )
                                    external
                                    override
                                    onlyOwner
                                {
                                    _removeAuthorizedAddressAtIndex(target, index);
                                }
                                /// @dev Gets all authorized addresses.
                                /// @return Array of authorized addresses.
                                function getAuthorizedAddresses()
                                    external
                                    override
                                    view
                                    returns (address[] memory)
                                {
                                    return authorities;
                                }
                                /// @dev Reverts if msg.sender is not authorized.
                                function _assertSenderIsAuthorized()
                                    internal
                                    view
                                {
                                    if (!authorized[msg.sender]) {
                                        LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.SenderNotAuthorizedError(msg.sender));
                                    }
                                }
                                /// @dev Authorizes an address.
                                /// @param target Address to authorize.
                                function _addAuthorizedAddress(address target)
                                    internal
                                {
                                    // Ensure that the target is not the zero address.
                                    if (target == address(0)) {
                                        LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.ZeroCantBeAuthorizedError());
                                    }
                                    // Ensure that the target is not already authorized.
                                    if (authorized[target]) {
                                        LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.TargetAlreadyAuthorizedError(target));
                                    }
                                    authorized[target] = true;
                                    authorities.push(target);
                                    emit AuthorizedAddressAdded(target, msg.sender);
                                }
                                /// @dev Removes authorizion of an address.
                                /// @param target Address to remove authorization from.
                                /// @param index Index of target in authorities array.
                                function _removeAuthorizedAddressAtIndex(
                                    address target,
                                    uint256 index
                                )
                                    internal
                                {
                                    if (!authorized[target]) {
                                        LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.TargetNotAuthorizedError(target));
                                    }
                                    if (index >= authorities.length) {
                                        LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.IndexOutOfBoundsError(
                                            index,
                                            authorities.length
                                        ));
                                    }
                                    if (authorities[index] != target) {
                                        LibRichErrorsV06.rrevert(LibAuthorizableRichErrorsV06.AuthorizedAddressMismatchError(
                                            authorities[index],
                                            target
                                        ));
                                    }
                                    delete authorized[target];
                                    authorities[index] = authorities[authorities.length - 1];
                                    authorities.pop();
                                    emit AuthorizedAddressRemoved(target, msg.sender);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./IOwnableV06.sol";
                            interface IAuthorizableV06 is
                                IOwnableV06
                            {
                                // Event logged when a new address is authorized.
                                event AuthorizedAddressAdded(
                                    address indexed target,
                                    address indexed caller
                                );
                                // Event logged when a currently authorized address is unauthorized.
                                event AuthorizedAddressRemoved(
                                    address indexed target,
                                    address indexed caller
                                );
                                /// @dev Authorizes an address.
                                /// @param target Address to authorize.
                                function addAuthorizedAddress(address target)
                                    external;
                                /// @dev Removes authorizion of an address.
                                /// @param target Address to remove authorization from.
                                function removeAuthorizedAddress(address target)
                                    external;
                                /// @dev Removes authorizion of an address.
                                /// @param target Address to remove authorization from.
                                /// @param index Index of target in authorities array.
                                function removeAuthorizedAddressAtIndex(
                                    address target,
                                    uint256 index
                                )
                                    external;
                                /// @dev Gets all authorized addresses.
                                /// @return authorizedAddresses Array of authorized addresses.
                                function getAuthorizedAddresses()
                                    external
                                    view
                                    returns (address[] memory authorizedAddresses);
                                /// @dev Whether an adderss is authorized to call privileged functions.
                                /// @param addr Address to query.
                                /// @return isAuthorized Whether the address is authorized.
                                function authorized(address addr) external view returns (bool isAuthorized);
                                /// @dev All addresseses authorized to call privileged functions.
                                /// @param idx Index of authorized address.
                                /// @return addr Authorized address.
                                function authorities(uint256 idx) external view returns (address addr);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            interface IOwnableV06 {
                                /// @dev Emitted by Ownable when ownership is transferred.
                                /// @param previousOwner The previous owner of the contract.
                                /// @param newOwner The new owner of the contract.
                                event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
                                /// @dev Transfers ownership of the contract to a new address.
                                /// @param newOwner The address that will become the owner.
                                function transferOwnership(address newOwner) external;
                                /// @dev The owner of this contract.
                                /// @return ownerAddress The owner address.
                                function owner() external view returns (address ownerAddress);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibAuthorizableRichErrorsV06 {
                                // bytes4(keccak256("AuthorizedAddressMismatchError(address,address)"))
                                bytes4 internal constant AUTHORIZED_ADDRESS_MISMATCH_ERROR_SELECTOR =
                                    0x140a84db;
                                // bytes4(keccak256("IndexOutOfBoundsError(uint256,uint256)"))
                                bytes4 internal constant INDEX_OUT_OF_BOUNDS_ERROR_SELECTOR =
                                    0xe9f83771;
                                // bytes4(keccak256("SenderNotAuthorizedError(address)"))
                                bytes4 internal constant SENDER_NOT_AUTHORIZED_ERROR_SELECTOR =
                                    0xb65a25b9;
                                // bytes4(keccak256("TargetAlreadyAuthorizedError(address)"))
                                bytes4 internal constant TARGET_ALREADY_AUTHORIZED_ERROR_SELECTOR =
                                    0xde16f1a0;
                                // bytes4(keccak256("TargetNotAuthorizedError(address)"))
                                bytes4 internal constant TARGET_NOT_AUTHORIZED_ERROR_SELECTOR =
                                    0xeb5108a2;
                                // bytes4(keccak256("ZeroCantBeAuthorizedError()"))
                                bytes internal constant ZERO_CANT_BE_AUTHORIZED_ERROR_BYTES =
                                    hex"57654fe4";
                                // solhint-disable func-name-mixedcase
                                function AuthorizedAddressMismatchError(
                                    address authorized,
                                    address target
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        AUTHORIZED_ADDRESS_MISMATCH_ERROR_SELECTOR,
                                        authorized,
                                        target
                                    );
                                }
                                function IndexOutOfBoundsError(
                                    uint256 index,
                                    uint256 length
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        INDEX_OUT_OF_BOUNDS_ERROR_SELECTOR,
                                        index,
                                        length
                                    );
                                }
                                function SenderNotAuthorizedError(address sender)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        SENDER_NOT_AUTHORIZED_ERROR_SELECTOR,
                                        sender
                                    );
                                }
                                function TargetAlreadyAuthorizedError(address target)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        TARGET_ALREADY_AUTHORIZED_ERROR_SELECTOR,
                                        target
                                    );
                                }
                                function TargetNotAuthorizedError(address target)
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        TARGET_NOT_AUTHORIZED_ERROR_SELECTOR,
                                        target
                                    );
                                }
                                function ZeroCantBeAuthorizedError()
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return ZERO_CANT_BE_AUTHORIZED_ERROR_BYTES;
                                }
                            }
                            /*
                              Copyright 2019 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./interfaces/IOwnableV06.sol";
                            import "./errors/LibRichErrorsV06.sol";
                            import "./errors/LibOwnableRichErrorsV06.sol";
                            contract OwnableV06 is
                                IOwnableV06
                            {
                                /// @dev The owner of this contract.
                                /// @return 0 The owner address.
                                address public override owner;
                                constructor() public {
                                    owner = msg.sender;
                                }
                                modifier onlyOwner() {
                                    _assertSenderIsOwner();
                                    _;
                                }
                                /// @dev Change the owner of this contract.
                                /// @param newOwner New owner address.
                                function transferOwnership(address newOwner)
                                    public
                                    override
                                    onlyOwner
                                {
                                    if (newOwner == address(0)) {
                                        LibRichErrorsV06.rrevert(LibOwnableRichErrorsV06.TransferOwnerToZeroError());
                                    } else {
                                        owner = newOwner;
                                        emit OwnershipTransferred(msg.sender, newOwner);
                                    }
                                }
                                function _assertSenderIsOwner()
                                    internal
                                    view
                                {
                                    if (msg.sender != owner) {
                                        LibRichErrorsV06.rrevert(LibOwnableRichErrorsV06.OnlyOwnerError(
                                            msg.sender,
                                            owner
                                        ));
                                    }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibOwnableRichErrorsV06 {
                                // bytes4(keccak256("OnlyOwnerError(address,address)"))
                                bytes4 internal constant ONLY_OWNER_ERROR_SELECTOR =
                                    0x1de45ad1;
                                // bytes4(keccak256("TransferOwnerToZeroError()"))
                                bytes internal constant TRANSFER_OWNER_TO_ZERO_ERROR_BYTES =
                                    hex"e69edc3e";
                                // solhint-disable func-name-mixedcase
                                function OnlyOwnerError(
                                    address sender,
                                    address owner
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        ONLY_OWNER_ERROR_SELECTOR,
                                        sender,
                                        owner
                                    );
                                }
                                function TransferOwnerToZeroError()
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return TRANSFER_OWNER_TO_ZERO_ERROR_BYTES;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/interfaces/IAuthorizableV06.sol";
                            /// @dev The allowance target for the TokenSpender feature.
                            interface IAllowanceTarget is
                                IAuthorizableV06
                            {
                                /// @dev Execute an arbitrary call. Only an authority can call this.
                                /// @param target The call target.
                                /// @param callData The call data.
                                /// @return resultData The data returned by the call.
                                function executeCall(
                                    address payable target,
                                    bytes calldata callData
                                )
                                    external
                                    returns (bytes memory resultData);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibOwnableRichErrorsV06.sol";
                            import "../errors/LibWalletRichErrors.sol";
                            import "./IFlashWallet.sol";
                            /// @dev A contract that can execute arbitrary calls from its owner.
                            contract FlashWallet is
                                IFlashWallet
                            {
                                // solhint-disable no-unused-vars,indent,no-empty-blocks
                                using LibRichErrorsV06 for bytes;
                                // solhint-disable
                                /// @dev Store the owner/deployer as an immutable to make this contract stateless.
                                address public override immutable owner;
                                // solhint-enable
                                constructor() public {
                                    // The deployer is the owner.
                                    owner = msg.sender;
                                }
                                /// @dev Allows only the (immutable) owner to call a function.
                                modifier onlyOwner() virtual {
                                    if (msg.sender != owner) {
                                        LibOwnableRichErrorsV06.OnlyOwnerError(
                                            msg.sender,
                                            owner
                                        ).rrevert();
                                    }
                                    _;
                                }
                                /// @dev Execute an arbitrary call. Only an authority can call this.
                                /// @param target The call target.
                                /// @param callData The call data.
                                /// @param value Ether to attach to the call.
                                /// @return resultData The data returned by the call.
                                function executeCall(
                                    address payable target,
                                    bytes calldata callData,
                                    uint256 value
                                )
                                    external
                                    payable
                                    override
                                    onlyOwner
                                    returns (bytes memory resultData)
                                {
                                    bool success;
                                    (success, resultData) = target.call{value: value}(callData);
                                    if (!success) {
                                        LibWalletRichErrors
                                            .WalletExecuteCallFailedError(
                                                address(this),
                                                target,
                                                callData,
                                                value,
                                                resultData
                                            )
                                            .rrevert();
                                    }
                                }
                                /// @dev Execute an arbitrary delegatecall, in the context of this puppet.
                                ///      Only an authority can call this.
                                /// @param target The call target.
                                /// @param callData The call data.
                                /// @return resultData The data returned by the call.
                                function executeDelegateCall(
                                    address payable target,
                                    bytes calldata callData
                                )
                                    external
                                    payable
                                    override
                                    onlyOwner
                                    returns (bytes memory resultData)
                                {
                                    bool success;
                                    (success, resultData) = target.delegatecall(callData);
                                    if (!success) {
                                        LibWalletRichErrors
                                            .WalletExecuteDelegateCallFailedError(
                                                address(this),
                                                target,
                                                callData,
                                                resultData
                                            )
                                            .rrevert();
                                    }
                                }
                                // solhint-disable
                                /// @dev Allows this contract to receive ether.
                                receive() external override payable {}
                                // solhint-enable
                                /// @dev Signal support for receiving ERC1155 tokens.
                                /// @param interfaceID The interface ID, as per ERC-165 rules.
                                /// @return hasSupport `true` if this contract supports an ERC-165 interface.
                                function supportsInterface(bytes4 interfaceID)
                                    external
                                    pure
                                    returns (bool hasSupport)
                                {
                                    return  interfaceID == this.supportsInterface.selector ||
                                            interfaceID == this.onERC1155Received.selector ^ this.onERC1155BatchReceived.selector ||
                                            interfaceID == this.tokenFallback.selector;
                                }
                                ///  @dev Allow this contract to receive ERC1155 tokens.
                                ///  @return success  `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))`
                                function onERC1155Received(
                                    address, // operator,
                                    address, // from,
                                    uint256, // id,
                                    uint256, // value,
                                    bytes calldata //data
                                )
                                    external
                                    pure
                                    returns (bytes4 success)
                                {
                                    return this.onERC1155Received.selector;
                                }
                                ///  @dev Allow this contract to receive ERC1155 tokens.
                                ///  @return success  `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))`
                                function onERC1155BatchReceived(
                                    address, // operator,
                                    address, // from,
                                    uint256[] calldata, // ids,
                                    uint256[] calldata, // values,
                                    bytes calldata // data
                                )
                                    external
                                    pure
                                    returns (bytes4 success)
                                {
                                    return this.onERC1155BatchReceived.selector;
                                }
                                /// @dev Allows this contract to receive ERC223 tokens.
                                function tokenFallback(
                                    address, // from,
                                    uint256, // value,
                                    bytes calldata // value
                                )
                                    external
                                    pure
                                {}
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/interfaces/IOwnableV06.sol";
                            /// @dev A contract that can execute arbitrary calls from its owner.
                            interface IFlashWallet {
                                /// @dev Execute an arbitrary call. Only an authority can call this.
                                /// @param target The call target.
                                /// @param callData The call data.
                                /// @param value Ether to attach to the call.
                                /// @return resultData The data returned by the call.
                                function executeCall(
                                    address payable target,
                                    bytes calldata callData,
                                    uint256 value
                                )
                                    external
                                    payable
                                    returns (bytes memory resultData);
                                /// @dev Execute an arbitrary delegatecall, in the context of this puppet.
                                ///      Only an authority can call this.
                                /// @param target The call target.
                                /// @param callData The call data.
                                /// @return resultData The data returned by the call.
                                function executeDelegateCall(
                                    address payable target,
                                    bytes calldata callData
                                )
                                    external
                                    payable
                                    returns (bytes memory resultData);
                                /// @dev Allows the puppet to receive ETH.
                                receive() external payable;
                                /// @dev Fetch the immutable owner/deployer of this contract.
                                /// @return owner_ The immutable owner/deployer/
                                function owner() external view returns (address owner_);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/AuthorizableV06.sol";
                            /// @dev A contract with a `die()` function.
                            interface IKillable {
                                function die() external;
                            }
                            /// @dev Deployer contract for ERC20 transformers.
                            ///      Only authorities may call `deploy()` and `kill()`.
                            contract TransformerDeployer is
                                AuthorizableV06
                            {
                                /// @dev Emitted when a contract is deployed via `deploy()`.
                                /// @param deployedAddress The address of the deployed contract.
                                /// @param nonce The deployment nonce.
                                /// @param sender The caller of `deploy()`.
                                event Deployed(address deployedAddress, uint256 nonce, address sender);
                                /// @dev Emitted when a contract is killed via `kill()`.
                                /// @param target The address of the contract being killed..
                                /// @param sender The caller of `kill()`.
                                event Killed(address target, address sender);
                                // @dev The current nonce of this contract.
                                uint256 public nonce = 1;
                                // @dev Mapping of deployed contract address to deployment nonce.
                                mapping (address => uint256) public toDeploymentNonce;
                                /// @dev Create this contract and register authorities.
                                constructor(address[] memory authorities) public {
                                    for (uint256 i = 0; i < authorities.length; ++i) {
                                        _addAuthorizedAddress(authorities[i]);
                                    }
                                }
                                /// @dev Deploy a new contract. Only callable by an authority.
                                ///      Any attached ETH will also be forwarded.
                                function deploy(bytes memory bytecode)
                                    public
                                    payable
                                    onlyAuthorized
                                    returns (address deployedAddress)
                                {
                                    uint256 deploymentNonce = nonce;
                                    nonce += 1;
                                    assembly {
                                        deployedAddress := create(callvalue(), add(bytecode, 32), mload(bytecode))
                                    }
                                    toDeploymentNonce[deployedAddress] = deploymentNonce;
                                    emit Deployed(deployedAddress, deploymentNonce, msg.sender);
                                }
                                /// @dev Call `die()` on a contract. Only callable by an authority.
                                function kill(IKillable target)
                                    public
                                    onlyAuthorized
                                {
                                    target.die();
                                    emit Killed(address(target), msg.sender);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            /// @dev Basic interface for a feature contract.
                            interface IFeature {
                                // solhint-disable func-name-mixedcase
                                /// @dev The name of this feature set.
                                function FEATURE_NAME() external view returns (string memory name);
                                /// @dev The version of this feature set.
                                function FEATURE_VERSION() external view returns (uint256 version);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            /// @dev Meta-transactions feature.
                            interface IMetaTransactions {
                                /// @dev Describes an exchange proxy meta transaction.
                                struct MetaTransactionData {
                                    // Signer of meta-transaction. On whose behalf to execute the MTX.
                                    address signer;
                                    // Required sender, or NULL for anyone.
                                    address sender;
                                    // Minimum gas price.
                                    uint256 minGasPrice;
                                    // Maximum gas price.
                                    uint256 maxGasPrice;
                                    // MTX is invalid after this time.
                                    uint256 expirationTime;
                                    // Nonce to make this MTX unique.
                                    uint256 salt;
                                    // Encoded call data to a function on the exchange proxy.
                                    bytes callData;
                                    // Amount of ETH to attach to the call.
                                    uint256 value;
                                    // ERC20 fee `signer` pays `sender`.
                                    IERC20TokenV06 feeToken;
                                    // ERC20 fee amount.
                                    uint256 feeAmount;
                                }
                                /// @dev Emitted whenever a meta-transaction is executed via
                                ///      `executeMetaTransaction()` or `executeMetaTransactions()`.
                                /// @param hash The meta-transaction hash.
                                /// @param selector The selector of the function being executed.
                                /// @param signer Who to execute the meta-transaction on behalf of.
                                /// @param sender Who executed the meta-transaction.
                                event MetaTransactionExecuted(
                                    bytes32 hash,
                                    bytes4 indexed selector,
                                    address signer,
                                    address sender
                                );
                                /// @dev Execute a single meta-transaction.
                                /// @param mtx The meta-transaction.
                                /// @param signature The signature by `mtx.signer`.
                                /// @return returnData The ABI-encoded result of the underlying call.
                                function executeMetaTransaction(
                                    MetaTransactionData calldata mtx,
                                    bytes calldata signature
                                )
                                    external
                                    payable
                                    returns (bytes memory returnData);
                                /// @dev Execute multiple meta-transactions.
                                /// @param mtxs The meta-transactions.
                                /// @param signatures The signature by each respective `mtx.signer`.
                                /// @return returnDatas The ABI-encoded results of the underlying calls.
                                function executeMetaTransactions(
                                    MetaTransactionData[] calldata mtxs,
                                    bytes[] calldata signatures
                                )
                                    external
                                    payable
                                    returns (bytes[] memory returnDatas);
                                /// @dev Execute a meta-transaction via `sender`. Privileged variant.
                                ///      Only callable from within.
                                /// @param sender Who is executing the meta-transaction..
                                /// @param mtx The meta-transaction.
                                /// @param signature The signature by `mtx.signer`.
                                /// @return returnData The ABI-encoded result of the underlying call.
                                function _executeMetaTransaction(
                                    address sender,
                                    MetaTransactionData calldata mtx,
                                    bytes calldata signature
                                )
                                    external
                                    payable
                                    returns (bytes memory returnData);
                                /// @dev Get the block at which a meta-transaction has been executed.
                                /// @param mtx The meta-transaction.
                                /// @return blockNumber The block height when the meta-transactioin was executed.
                                function getMetaTransactionExecutedBlock(MetaTransactionData calldata mtx)
                                    external
                                    view
                                    returns (uint256 blockNumber);
                                /// @dev Get the block at which a meta-transaction hash has been executed.
                                /// @param mtxHash The meta-transaction hash.
                                /// @return blockNumber The block height when the meta-transactioin was executed.
                                function getMetaTransactionHashExecutedBlock(bytes32 mtxHash)
                                    external
                                    view
                                    returns (uint256 blockNumber);
                                /// @dev Get the EIP712 hash of a meta-transaction.
                                /// @param mtx The meta-transaction.
                                /// @return mtxHash The EIP712 hash of `mtx`.
                                function getMetaTransactionHash(MetaTransactionData calldata mtx)
                                    external
                                    view
                                    returns (bytes32 mtxHash);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            interface IERC20TokenV06 {
                                // solhint-disable no-simple-event-func-name
                                event Transfer(
                                    address indexed from,
                                    address indexed to,
                                    uint256 value
                                );
                                event Approval(
                                    address indexed owner,
                                    address indexed spender,
                                    uint256 value
                                );
                                /// @dev send `value` token to `to` from `msg.sender`
                                /// @param to The address of the recipient
                                /// @param value The amount of token to be transferred
                                /// @return True if transfer was successful
                                function transfer(address to, uint256 value)
                                    external
                                    returns (bool);
                                /// @dev send `value` token to `to` from `from` on the condition it is approved by `from`
                                /// @param from The address of the sender
                                /// @param to The address of the recipient
                                /// @param value The amount of token to be transferred
                                /// @return True if transfer was successful
                                function transferFrom(
                                    address from,
                                    address to,
                                    uint256 value
                                )
                                    external
                                    returns (bool);
                                /// @dev `msg.sender` approves `spender` to spend `value` tokens
                                /// @param spender The address of the account able to transfer the tokens
                                /// @param value The amount of wei to be approved for transfer
                                /// @return Always true if the call has enough gas to complete execution
                                function approve(address spender, uint256 value)
                                    external
                                    returns (bool);
                                /// @dev Query total supply of token
                                /// @return Total supply of token
                                function totalSupply()
                                    external
                                    view
                                    returns (uint256);
                                /// @dev Get the balance of `owner`.
                                /// @param owner The address from which the balance will be retrieved
                                /// @return Balance of owner
                                function balanceOf(address owner)
                                    external
                                    view
                                    returns (uint256);
                                /// @dev Get the allowance for `spender` to spend from `owner`.
                                /// @param owner The address of the account owning tokens
                                /// @param spender The address of the account able to transfer the tokens
                                /// @return Amount of remaining tokens allowed to spent
                                function allowance(address owner, address spender)
                                    external
                                    view
                                    returns (uint256);
                                /// @dev Get the number of decimals this token has.
                                function decimals()
                                    external
                                    view
                                    returns (uint8);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/interfaces/IOwnableV06.sol";
                            // solhint-disable no-empty-blocks
                            /// @dev Owner management and migration features.
                            interface IOwnable is
                                IOwnableV06
                            {
                                /// @dev Emitted when `migrate()` is called.
                                /// @param caller The caller of `migrate()`.
                                /// @param migrator The migration contract.
                                /// @param newOwner The address of the new owner.
                                event Migrated(address caller, address migrator, address newOwner);
                                /// @dev Execute a migration function in the context of the ZeroEx contract.
                                ///      The result of the function being called should be the magic bytes
                                ///      0x2c64c5ef (`keccack('MIGRATE_SUCCESS')`). Only callable by the owner.
                                ///      The owner will be temporarily set to `address(this)` inside the call.
                                ///      Before returning, the owner will be set to `newOwner`.
                                /// @param target The migrator contract address.
                                /// @param newOwner The address of the new owner.
                                /// @param data The call data.
                                function migrate(address target, bytes calldata data, address newOwner) external;
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            /// @dev Feature for validating signatures.
                            interface ISignatureValidator {
                               /// @dev Allowed signature types.
                                enum SignatureType {
                                    Illegal,                     // 0x00, default value
                                    Invalid,                     // 0x01
                                    EIP712,                      // 0x02
                                    EthSign,                     // 0x03
                                    NSignatureTypes              // 0x04, number of signature types. Always leave at end.
                                }
                                /// @dev Validate that `hash` was signed by `signer` given `signature`.
                                ///      Reverts otherwise.
                                /// @param hash The hash that was signed.
                                /// @param signer The signer of the hash.
                                /// @param signature The signature. The last byte of this signature should
                                ///        be a member of the `SignatureType` enum.
                                function validateHashSignature(
                                    bytes32 hash,
                                    address signer,
                                    bytes calldata signature
                                )
                                    external
                                    view;
                                /// @dev Check that `hash` was signed by `signer` given `signature`.
                                /// @param hash The hash that was signed.
                                /// @param signer The signer of the hash.
                                /// @param signature The signature. The last byte of this signature should
                                ///        be a member of the `SignatureType` enum.
                                /// @return isValid `true` on success.
                                function isValidHashSignature(
                                    bytes32 hash,
                                    address signer,
                                    bytes calldata signature
                                )
                                    external
                                    view
                                    returns (bool isValid);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            /// @dev Basic registry management features.
                            interface ISimpleFunctionRegistry {
                                /// @dev A function implementation was updated via `extend()` or `rollback()`.
                                /// @param selector The function selector.
                                /// @param oldImpl The implementation contract address being replaced.
                                /// @param newImpl The replacement implementation contract address.
                                event ProxyFunctionUpdated(bytes4 indexed selector, address oldImpl, address newImpl);
                                /// @dev Roll back to a prior implementation of a function.
                                /// @param selector The function selector.
                                /// @param targetImpl The address of an older implementation of the function.
                                function rollback(bytes4 selector, address targetImpl) external;
                                /// @dev Register or replace a function.
                                /// @param selector The function selector.
                                /// @param impl The implementation contract for the function.
                                function extend(bytes4 selector, address impl) external;
                                /// @dev Retrieve the length of the rollback history for a function.
                                /// @param selector The function selector.
                                /// @return rollbackLength The number of items in the rollback history for
                                ///         the function.
                                function getRollbackLength(bytes4 selector)
                                    external
                                    view
                                    returns (uint256 rollbackLength);
                                /// @dev Retrieve an entry in the rollback history for a function.
                                /// @param selector The function selector.
                                /// @param idx The index in the rollback history.
                                /// @return impl An implementation address for the function at
                                ///         index `idx`.
                                function getRollbackEntryAtIndex(bytes4 selector, uint256 idx)
                                    external
                                    view
                                    returns (address impl);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            /// @dev Feature that allows spending token allowances.
                            interface ITokenSpender {
                                /// @dev Transfers ERC20 tokens from `owner` to `to`.
                                ///      Only callable from within.
                                /// @param token The token to spend.
                                /// @param owner The owner of the tokens.
                                /// @param to The recipient of the tokens.
                                /// @param amount The amount of `token` to transfer.
                                function _spendERC20Tokens(
                                    IERC20TokenV06 token,
                                    address owner,
                                    address to,
                                    uint256 amount
                                )
                                    external;
                                /// @dev Gets the maximum amount of an ERC20 token `token` that can be
                                ///      pulled from `owner`.
                                /// @param token The token to spend.
                                /// @param owner The owner of the tokens.
                                /// @return amount The amount of tokens that can be pulled.
                                function getSpendableERC20BalanceOf(IERC20TokenV06 token, address owner)
                                    external
                                    view
                                    returns (uint256 amount);
                                /// @dev Get the address of the allowance target.
                                /// @return target The target of token allowances.
                                function getAllowanceTarget() external view returns (address target);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "../transformers/IERC20Transformer.sol";
                            import "../external/IFlashWallet.sol";
                            /// @dev Feature to composably transform between ERC20 tokens.
                            interface ITransformERC20 {
                                /// @dev Defines a transformation to run in `transformERC20()`.
                                struct Transformation {
                                    // The deployment nonce for the transformer.
                                    // The address of the transformer contract will be derived from this
                                    // value.
                                    uint32 deploymentNonce;
                                    // Arbitrary data to pass to the transformer.
                                    bytes data;
                                }
                                /// @dev Raised upon a successful `transformERC20`.
                                /// @param taker The taker (caller) address.
                                /// @param inputToken The token being provided by the taker.
                                ///        If `0xeee...`, ETH is implied and should be provided with the call.`
                                /// @param outputToken The token to be acquired by the taker.
                                ///        `0xeee...` implies ETH.
                                /// @param inputTokenAmount The amount of `inputToken` to take from the taker.
                                /// @param outputTokenAmount The amount of `outputToken` received by the taker.
                                event TransformedERC20(
                                    address indexed taker,
                                    address inputToken,
                                    address outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 outputTokenAmount
                                );
                                /// @dev Raised when `setTransformerDeployer()` is called.
                                /// @param transformerDeployer The new deployer address.
                                event TransformerDeployerUpdated(address transformerDeployer);
                                /// @dev Replace the allowed deployer for transformers.
                                ///      Only callable by the owner.
                                /// @param transformerDeployer The address of the trusted deployer for transformers.
                                function setTransformerDeployer(address transformerDeployer)
                                    external;
                                /// @dev Deploy a new flash wallet instance and replace the current one with it.
                                ///      Useful if we somehow break the current wallet instance.
                                ///       Only callable by the owner.
                                /// @return wallet The new wallet instance.
                                function createTransformWallet()
                                    external
                                    returns (IFlashWallet wallet);
                                /// @dev Executes a series of transformations to convert an ERC20 `inputToken`
                                ///      to an ERC20 `outputToken`.
                                /// @param inputToken The token being provided by the sender.
                                ///        If `0xeee...`, ETH is implied and should be provided with the call.`
                                /// @param outputToken The token to be acquired by the sender.
                                ///        `0xeee...` implies ETH.
                                /// @param inputTokenAmount The amount of `inputToken` to take from the sender.
                                /// @param minOutputTokenAmount The minimum amount of `outputToken` the sender
                                ///        must receive for the entire transformation to succeed.
                                /// @param transformations The transformations to execute on the token balance(s)
                                ///        in sequence.
                                /// @return outputTokenAmount The amount of `outputToken` received by the sender.
                                function transformERC20(
                                    IERC20TokenV06 inputToken,
                                    IERC20TokenV06 outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 minOutputTokenAmount,
                                    Transformation[] calldata transformations
                                )
                                    external
                                    payable
                                    returns (uint256 outputTokenAmount);
                                /// @dev Internal version of `transformERC20()`. Only callable from within.
                                /// @param callDataHash Hash of the ingress calldata.
                                /// @param taker The taker address.
                                /// @param inputToken The token being provided by the taker.
                                ///        If `0xeee...`, ETH is implied and should be provided with the call.`
                                /// @param outputToken The token to be acquired by the taker.
                                ///        `0xeee...` implies ETH.
                                /// @param inputTokenAmount The amount of `inputToken` to take from the taker.
                                /// @param minOutputTokenAmount The minimum amount of `outputToken` the taker
                                ///        must receive for the entire transformation to succeed.
                                /// @param transformations The transformations to execute on the token balance(s)
                                ///        in sequence.
                                /// @return outputTokenAmount The amount of `outputToken` received by the taker.
                                function _transformERC20(
                                    bytes32 callDataHash,
                                    address payable taker,
                                    IERC20TokenV06 inputToken,
                                    IERC20TokenV06 outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 minOutputTokenAmount,
                                    Transformation[] calldata transformations
                                )
                                    external
                                    payable
                                    returns (uint256 outputTokenAmount);
                                /// @dev Return the current wallet instance that will serve as the execution
                                ///      context for transformations.
                                /// @return wallet The wallet instance.
                                function getTransformWallet()
                                    external
                                    view
                                    returns (IFlashWallet wallet);
                                /// @dev Return the allowed deployer for transformers.
                                /// @return deployer The transform deployer address.
                                function getTransformerDeployer()
                                    external
                                    view
                                    returns (address deployer);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            /// @dev A transformation callback used in `TransformERC20.transformERC20()`.
                            interface IERC20Transformer {
                                /// @dev Called from `TransformERC20.transformERC20()`. This will be
                                ///      delegatecalled in the context of the FlashWallet instance being used.
                                /// @param callDataHash The hash of the `TransformERC20.transformERC20()` calldata.
                                /// @param taker The taker address (caller of `TransformERC20.transformERC20()`).
                                /// @param data Arbitrary data to pass to the transformer.
                                /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
                                function transform(
                                    bytes32 callDataHash,
                                    address payable taker,
                                    bytes calldata data
                                )
                                    external
                                    returns (bytes4 success);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
                            import "../errors/LibMetaTransactionsRichErrors.sol";
                            import "../fixins/FixinCommon.sol";
                            import "../fixins/FixinEIP712.sol";
                            import "../migrations/LibMigrate.sol";
                            import "../storage/LibMetaTransactionsStorage.sol";
                            import "./IMetaTransactions.sol";
                            import "./ITransformERC20.sol";
                            import "./ISignatureValidator.sol";
                            import "./ITokenSpender.sol";
                            import "./IFeature.sol";
                            /// @dev MetaTransactions feature.
                            contract MetaTransactions is
                                IFeature,
                                IMetaTransactions,
                                FixinCommon,
                                FixinEIP712
                            {
                                using LibBytesV06 for bytes;
                                using LibRichErrorsV06 for bytes;
                                /// @dev Intermediate state vars to avoid stack overflows.
                                struct ExecuteState {
                                    address sender;
                                    bytes32 hash;
                                    MetaTransactionData mtx;
                                    bytes signature;
                                    bytes4 selector;
                                    uint256 selfBalance;
                                    uint256 executedBlockNumber;
                                }
                                struct TransformERC20Args {
                                    IERC20TokenV06 inputToken;
                                    IERC20TokenV06 outputToken;
                                    uint256 inputTokenAmount;
                                    uint256 minOutputTokenAmount;
                                    ITransformERC20.Transformation[] transformations;
                                }
                                /// @dev Name of this feature.
                                string public constant override FEATURE_NAME = "MetaTransactions";
                                /// @dev Version of this feature.
                                uint256 public immutable override FEATURE_VERSION = _encodeVersion(1, 0, 0);
                                /// @dev EIP712 typehash of the `MetaTransactionData` struct.
                                bytes32 public immutable MTX_EIP712_TYPEHASH = keccak256(
                                    "MetaTransactionData("
                                        "address signer,"
                                        "address sender,"
                                        "uint256 minGasPrice,"
                                        "uint256 maxGasPrice,"
                                        "uint256 expirationTime,"
                                        "uint256 salt,"
                                        "bytes callData,"
                                        "uint256 value,"
                                        "address feeToken,"
                                        "uint256 feeAmount"
                                    ")"
                                );
                                constructor(address zeroExAddress)
                                    public
                                    FixinCommon()
                                    FixinEIP712(zeroExAddress)
                                {
                                    // solhint-disable-next-line no-empty-blocks
                                }
                                /// @dev Initialize and register this feature.
                                ///      Should be delegatecalled by `Migrate.migrate()`.
                                /// @return success `LibMigrate.SUCCESS` on success.
                                function migrate()
                                    external
                                    returns (bytes4 success)
                                {
                                    _registerFeatureFunction(this.executeMetaTransaction.selector);
                                    _registerFeatureFunction(this.executeMetaTransactions.selector);
                                    _registerFeatureFunction(this._executeMetaTransaction.selector);
                                    _registerFeatureFunction(this.getMetaTransactionExecutedBlock.selector);
                                    _registerFeatureFunction(this.getMetaTransactionHashExecutedBlock.selector);
                                    _registerFeatureFunction(this.getMetaTransactionHash.selector);
                                    return LibMigrate.MIGRATE_SUCCESS;
                                }
                                /// @dev Execute a single meta-transaction.
                                /// @param mtx The meta-transaction.
                                /// @param signature The signature by `mtx.signer`.
                                /// @return returnData The ABI-encoded result of the underlying call.
                                function executeMetaTransaction(
                                    MetaTransactionData memory mtx,
                                    bytes memory signature
                                )
                                    public
                                    payable
                                    override
                                    returns (bytes memory returnData)
                                {
                                    return _executeMetaTransactionPrivate(
                                        msg.sender,
                                        mtx,
                                        signature
                                    );
                                }
                                /// @dev Execute multiple meta-transactions.
                                /// @param mtxs The meta-transactions.
                                /// @param signatures The signature by each respective `mtx.signer`.
                                /// @return returnDatas The ABI-encoded results of the underlying calls.
                                function executeMetaTransactions(
                                    MetaTransactionData[] memory mtxs,
                                    bytes[] memory signatures
                                )
                                    public
                                    payable
                                    override
                                    returns (bytes[] memory returnDatas)
                                {
                                    if (mtxs.length != signatures.length) {
                                        LibMetaTransactionsRichErrors.InvalidMetaTransactionsArrayLengthsError(
                                            mtxs.length,
                                            signatures.length
                                        ).rrevert();
                                    }
                                    returnDatas = new bytes[](mtxs.length);
                                    for (uint256 i = 0; i < mtxs.length; ++i) {
                                        returnDatas[i] = _executeMetaTransactionPrivate(
                                            msg.sender,
                                            mtxs[i],
                                            signatures[i]
                                        );
                                    }
                                }
                                /// @dev Execute a meta-transaction via `sender`. Privileged variant.
                                ///      Only callable from within.
                                /// @param sender Who is executing the meta-transaction..
                                /// @param mtx The meta-transaction.
                                /// @param signature The signature by `mtx.signer`.
                                /// @return returnData The ABI-encoded result of the underlying call.
                                function _executeMetaTransaction(
                                    address sender,
                                    MetaTransactionData memory mtx,
                                    bytes memory signature
                                )
                                    public
                                    payable
                                    override
                                    onlySelf
                                    returns (bytes memory returnData)
                                {
                                    return _executeMetaTransactionPrivate(sender, mtx, signature);
                                }
                                /// @dev Get the block at which a meta-transaction has been executed.
                                /// @param mtx The meta-transaction.
                                /// @return blockNumber The block height when the meta-transactioin was executed.
                                function getMetaTransactionExecutedBlock(MetaTransactionData memory mtx)
                                    public
                                    override
                                    view
                                    returns (uint256 blockNumber)
                                {
                                    return getMetaTransactionHashExecutedBlock(getMetaTransactionHash(mtx));
                                }
                                /// @dev Get the block at which a meta-transaction hash has been executed.
                                /// @param mtxHash The meta-transaction hash.
                                /// @return blockNumber The block height when the meta-transactioin was executed.
                                function getMetaTransactionHashExecutedBlock(bytes32 mtxHash)
                                    public
                                    override
                                    view
                                    returns (uint256 blockNumber)
                                {
                                    return LibMetaTransactionsStorage.getStorage().mtxHashToExecutedBlockNumber[mtxHash];
                                }
                                /// @dev Get the EIP712 hash of a meta-transaction.
                                /// @param mtx The meta-transaction.
                                /// @return mtxHash The EIP712 hash of `mtx`.
                                function getMetaTransactionHash(MetaTransactionData memory mtx)
                                    public
                                    override
                                    view
                                    returns (bytes32 mtxHash)
                                {
                                    return _getEIP712Hash(keccak256(abi.encode(
                                        MTX_EIP712_TYPEHASH,
                                        mtx.signer,
                                        mtx.sender,
                                        mtx.minGasPrice,
                                        mtx.maxGasPrice,
                                        mtx.expirationTime,
                                        mtx.salt,
                                        keccak256(mtx.callData),
                                        mtx.value,
                                        mtx.feeToken,
                                        mtx.feeAmount
                                    )));
                                }
                                /// @dev Execute a meta-transaction by `sender`. Low-level, hidden variant.
                                /// @param sender Who is executing the meta-transaction..
                                /// @param mtx The meta-transaction.
                                /// @param signature The signature by `mtx.signer`.
                                /// @return returnData The ABI-encoded result of the underlying call.
                                function _executeMetaTransactionPrivate(
                                    address sender,
                                    MetaTransactionData memory mtx,
                                    bytes memory signature
                                )
                                    private
                                    returns (bytes memory returnData)
                                {
                                    ExecuteState memory state;
                                    state.sender = sender;
                                    state.hash = getMetaTransactionHash(mtx);
                                    state.mtx = mtx;
                                    state.signature = signature;
                                    _validateMetaTransaction(state);
                                    // Mark the transaction executed.
                                    assert(block.number > 0);
                                    LibMetaTransactionsStorage.getStorage()
                                        .mtxHashToExecutedBlockNumber[state.hash] = block.number;
                                    // Execute the call based on the selector.
                                    state.selector = mtx.callData.readBytes4(0);
                                    if (state.selector == ITransformERC20.transformERC20.selector) {
                                        returnData = _executeTransformERC20Call(state);
                                    } else {
                                        LibMetaTransactionsRichErrors
                                            .MetaTransactionUnsupportedFunctionError(state.hash, state.selector)
                                            .rrevert();
                                    }
                                    // Pay the fee to the sender.
                                    if (mtx.feeAmount > 0) {
                                        ITokenSpender(address(this))._spendERC20Tokens(
                                            mtx.feeToken,
                                            mtx.signer, // From the signer.
                                            sender, // To the sender.
                                            mtx.feeAmount
                                        );
                                    }
                                    emit MetaTransactionExecuted(
                                        state.hash,
                                        state.selector,
                                        mtx.signer,
                                        mtx.sender
                                    );
                                }
                                /// @dev Validate that a meta-transaction is executable.
                                function _validateMetaTransaction(ExecuteState memory state)
                                    private
                                    view
                                {
                                    // Must be from the required sender, if set.
                                    if (state.mtx.sender != address(0) && state.mtx.sender != state.sender) {
                                        LibMetaTransactionsRichErrors
                                            .MetaTransactionWrongSenderError(
                                                state.hash,
                                                state.sender,
                                                state.mtx.sender
                                            ).rrevert();
                                    }
                                    // Must not be expired.
                                    if (state.mtx.expirationTime <= block.timestamp) {
                                        LibMetaTransactionsRichErrors
                                            .MetaTransactionExpiredError(
                                                state.hash,
                                                block.timestamp,
                                                state.mtx.expirationTime
                                            ).rrevert();
                                    }
                                    // Must have a valid gas price.
                                    if (state.mtx.minGasPrice > tx.gasprice || state.mtx.maxGasPrice < tx.gasprice) {
                                        LibMetaTransactionsRichErrors
                                            .MetaTransactionGasPriceError(
                                                state.hash,
                                                tx.gasprice,
                                                state.mtx.minGasPrice,
                                                state.mtx.maxGasPrice
                                            ).rrevert();
                                    }
                                    // Must have enough ETH.
                                    state.selfBalance  = address(this).balance;
                                    if (state.mtx.value > state.selfBalance) {
                                        LibMetaTransactionsRichErrors
                                            .MetaTransactionInsufficientEthError(
                                                state.hash,
                                                state.selfBalance,
                                                state.mtx.value
                                            ).rrevert();
                                    }
                                    // Must be signed by signer.
                                    try
                                        ISignatureValidator(address(this))
                                            .validateHashSignature(state.hash, state.mtx.signer, state.signature)
                                    {}
                                    catch (bytes memory err) {
                                        LibMetaTransactionsRichErrors
                                            .MetaTransactionInvalidSignatureError(
                                                state.hash,
                                                state.signature,
                                                err
                                            ).rrevert();
                                    }
                                    // Transaction must not have been already executed.
                                    state.executedBlockNumber = LibMetaTransactionsStorage
                                        .getStorage().mtxHashToExecutedBlockNumber[state.hash];
                                    if (state.executedBlockNumber != 0) {
                                        LibMetaTransactionsRichErrors
                                            .MetaTransactionAlreadyExecutedError(
                                                state.hash,
                                                state.executedBlockNumber
                                            ).rrevert();
                                    }
                                }
                                /// @dev Execute a `ITransformERC20.transformERC20()` meta-transaction call
                                ///      by decoding the call args and translating the call to the internal
                                ///      `ITransformERC20._transformERC20()` variant, where we can override
                                ///      the taker address.
                                function _executeTransformERC20Call(ExecuteState memory state)
                                    private
                                    returns (bytes memory returnData)
                                {
                                    // HACK(dorothy-zbornak): `abi.decode()` with the individual args
                                    // will cause a stack overflow. But we can prefix the call data with an
                                    // offset to transform it into the encoding for the equivalent single struct arg.
                                    // Decoding a single struct consumes far less stack space.
                                    TransformERC20Args memory args;
                                    {
                                        bytes memory encodedStructArgs = new bytes(state.mtx.callData.length - 4 + 32);
                                        // Copy the args data from the original, after the new struct offset prefix.
                                        bytes memory fromCallData = state.mtx.callData;
                                        assert(fromCallData.length >= 4);
                                        uint256 fromMem;
                                        uint256 toMem;
                                        assembly {
                                            // Prefix the original calldata with a struct offset,
                                            // which is just one word over.
                                            mstore(add(encodedStructArgs, 32), 32)
                                            // Copy everything after the selector.
                                            fromMem := add(fromCallData, 36)
                                            // Start copying after the struct offset.
                                            toMem := add(encodedStructArgs, 64)
                                        }
                                        LibBytesV06.memCopy(toMem, fromMem, fromCallData.length - 4);
                                        // Decode call args for `ITransformERC20.transformERC20()` as a struct.
                                        args = abi.decode(encodedStructArgs, (TransformERC20Args));
                                    }
                                    // Call `ITransformERC20._transformERC20()` (internal variant).
                                    return _callSelf(
                                        state.hash,
                                        abi.encodeWithSelector(
                                            ITransformERC20._transformERC20.selector,
                                            keccak256(state.mtx.callData),
                                            state.mtx.signer, // taker is mtx signer
                                            args.inputToken,
                                            args.outputToken,
                                            args.inputTokenAmount,
                                            args.minOutputTokenAmount,
                                            args.transformations
                                        ),
                                        state.mtx.value
                                    );
                                }
                                /// @dev Make an arbitrary internal, meta-transaction call.
                                ///      Warning: Do not let unadulerated `callData` into this function.
                                function _callSelf(bytes32 hash, bytes memory callData, uint256 value)
                                    private
                                    returns (bytes memory returnData)
                                {
                                    bool success;
                                    (success, returnData) = address(this).call{value: value}(callData);
                                    if (!success) {
                                        LibMetaTransactionsRichErrors.MetaTransactionCallFailedError(
                                            hash,
                                            callData,
                                            returnData
                                        ).rrevert();
                                    }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "../errors/LibCommonRichErrors.sol";
                            import "../errors/LibOwnableRichErrors.sol";
                            import "../features/IOwnable.sol";
                            import "../features/ISimpleFunctionRegistry.sol";
                            /// @dev Common feature utilities.
                            abstract contract FixinCommon {
                                using LibRichErrorsV06 for bytes;
                                /// @dev The implementation address of this feature.
                                address internal immutable _implementation;
                                /// @dev The caller must be this contract.
                                modifier onlySelf() virtual {
                                    if (msg.sender != address(this)) {
                                        LibCommonRichErrors.OnlyCallableBySelfError(msg.sender).rrevert();
                                    }
                                    _;
                                }
                                /// @dev The caller of this function must be the owner.
                                modifier onlyOwner() virtual {
                                    {
                                        address owner = IOwnable(address(this)).owner();
                                        if (msg.sender != owner) {
                                            LibOwnableRichErrors.OnlyOwnerError(
                                                msg.sender,
                                                owner
                                            ).rrevert();
                                        }
                                    }
                                    _;
                                }
                                constructor() internal {
                                    // Remember this feature's original address.
                                    _implementation = address(this);
                                }
                                /// @dev Registers a function implemented by this feature at `_implementation`.
                                ///      Can and should only be called within a `migrate()`.
                                /// @param selector The selector of the function whose implementation
                                ///        is at `_implementation`.
                                function _registerFeatureFunction(bytes4 selector)
                                    internal
                                {
                                    ISimpleFunctionRegistry(address(this)).extend(selector, _implementation);
                                }
                                /// @dev Encode a feature version as a `uint256`.
                                /// @param major The major version number of the feature.
                                /// @param minor The minor version number of the feature.
                                /// @param revision The revision number of the feature.
                                /// @return encodedVersion The encoded version number.
                                function _encodeVersion(uint32 major, uint32 minor, uint32 revision)
                                    internal
                                    pure
                                    returns (uint256 encodedVersion)
                                {
                                    return (major << 64) | (minor << 32) | revision;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "../errors/LibCommonRichErrors.sol";
                            import "../errors/LibOwnableRichErrors.sol";
                            import "../features/IOwnable.sol";
                            /// @dev EIP712 helpers for features.
                            abstract contract FixinEIP712 {
                                /// @dev The domain hash separator for the entire exchange proxy.
                                bytes32 public immutable EIP712_DOMAIN_SEPARATOR;
                                constructor(address zeroExAddress) internal {
                                    // Compute `EIP712_DOMAIN_SEPARATOR`
                                    {
                                        uint256 chainId;
                                        assembly { chainId := chainid() }
                                        EIP712_DOMAIN_SEPARATOR = keccak256(
                                            abi.encode(
                                                keccak256(
                                                    "EIP712Domain("
                                                        "string name,"
                                                        "string version,"
                                                        "uint256 chainId,"
                                                        "address verifyingContract"
                                                    ")"
                                                ),
                                                keccak256("ZeroEx"),
                                                keccak256("1.0.0"),
                                                chainId,
                                                zeroExAddress
                                            )
                                        );
                                    }
                                }
                                function _getEIP712Hash(bytes32 structHash)
                                    internal
                                    view
                                    returns (bytes32 eip712Hash)
                                {
                                    return keccak256(abi.encodePacked(
                                        hex"1901",
                                        EIP712_DOMAIN_SEPARATOR,
                                        structHash
                                    ));
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "../errors/LibOwnableRichErrors.sol";
                            library LibMigrate {
                                /// @dev Magic bytes returned by a migrator to indicate success.
                                ///      This is `keccack('MIGRATE_SUCCESS')`.
                                bytes4 internal constant MIGRATE_SUCCESS = 0x2c64c5ef;
                                using LibRichErrorsV06 for bytes;
                                /// @dev Perform a delegatecall and ensure it returns the magic bytes.
                                /// @param target The call target.
                                /// @param data The call data.
                                function delegatecallMigrateFunction(
                                    address target,
                                    bytes memory data
                                )
                                    internal
                                {
                                    (bool success, bytes memory resultData) = target.delegatecall(data);
                                    if (!success ||
                                        resultData.length != 32 ||
                                        abi.decode(resultData, (bytes4)) != MIGRATE_SUCCESS)
                                    {
                                        LibOwnableRichErrors.MigrateCallFailedError(target, resultData).rrevert();
                                    }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "./LibStorage.sol";
                            /// @dev Storage helpers for the `MetaTransactions` feature.
                            library LibMetaTransactionsStorage {
                                /// @dev Storage bucket for this feature.
                                struct Storage {
                                    // The block number when a hash was executed.
                                    mapping (bytes32 => uint256) mtxHashToExecutedBlockNumber;
                                }
                                /// @dev Get the storage bucket for this contract.
                                function getStorage() internal pure returns (Storage storage stor) {
                                    uint256 storageSlot = LibStorage.getStorageSlot(
                                        LibStorage.StorageId.MetaTransactions
                                    );
                                    // Dip into assembly to change the slot pointed to by the local
                                    // variable `stor`.
                                    // See https://solidity.readthedocs.io/en/v0.6.8/assembly.html?highlight=slot#access-to-external-variables-functions-and-libraries
                                    assembly { stor_slot := storageSlot }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "../fixins/FixinCommon.sol";
                            import "../errors/LibOwnableRichErrors.sol";
                            import "../storage/LibOwnableStorage.sol";
                            import "../migrations/LibBootstrap.sol";
                            import "../migrations/LibMigrate.sol";
                            import "./IFeature.sol";
                            import "./IOwnable.sol";
                            import "./SimpleFunctionRegistry.sol";
                            /// @dev Owner management features.
                            contract Ownable is
                                IFeature,
                                IOwnable,
                                FixinCommon
                            {
                                /// @dev Name of this feature.
                                string public constant override FEATURE_NAME = "Ownable";
                                /// @dev Version of this feature.
                                uint256 public immutable override FEATURE_VERSION = _encodeVersion(1, 0, 0);
                                using LibRichErrorsV06 for bytes;
                                constructor() public FixinCommon() {
                                    // solhint-disable-next-line no-empty-blocks
                                }
                                /// @dev Initializes this feature. The intial owner will be set to this (ZeroEx)
                                ///      to allow the bootstrappers to call `extend()`. Ownership should be
                                ///      transferred to the real owner by the bootstrapper after
                                ///      bootstrapping is complete.
                                /// @return success Magic bytes if successful.
                                function bootstrap() external returns (bytes4 success) {
                                    // Set the owner to ourselves to allow bootstrappers to call `extend()`.
                                    LibOwnableStorage.getStorage().owner = address(this);
                                    // Register feature functions.
                                    SimpleFunctionRegistry(address(this))._extendSelf(this.transferOwnership.selector, _implementation);
                                    SimpleFunctionRegistry(address(this))._extendSelf(this.owner.selector, _implementation);
                                    SimpleFunctionRegistry(address(this))._extendSelf(this.migrate.selector, _implementation);
                                    return LibBootstrap.BOOTSTRAP_SUCCESS;
                                }
                                /// @dev Change the owner of this contract.
                                ///      Only directly callable by the owner.
                                /// @param newOwner New owner address.
                                function transferOwnership(address newOwner)
                                    external
                                    override
                                    onlyOwner
                                {
                                    LibOwnableStorage.Storage storage proxyStor = LibOwnableStorage.getStorage();
                                    if (newOwner == address(0)) {
                                        LibOwnableRichErrors.TransferOwnerToZeroError().rrevert();
                                    } else {
                                        proxyStor.owner = newOwner;
                                        emit OwnershipTransferred(msg.sender, newOwner);
                                    }
                                }
                                /// @dev Execute a migration function in the context of the ZeroEx contract.
                                ///      The result of the function being called should be the magic bytes
                                ///      0x2c64c5ef (`keccack('MIGRATE_SUCCESS')`). Only callable by the owner.
                                ///      Temporarily sets the owner to ourselves so we can perform admin functions.
                                ///      Before returning, the owner will be set to `newOwner`.
                                /// @param target The migrator contract address.
                                /// @param data The call data.
                                /// @param newOwner The address of the new owner.
                                function migrate(address target, bytes calldata data, address newOwner)
                                    external
                                    override
                                    onlyOwner
                                {
                                    if (newOwner == address(0)) {
                                        LibOwnableRichErrors.TransferOwnerToZeroError().rrevert();
                                    }
                                    LibOwnableStorage.Storage storage stor = LibOwnableStorage.getStorage();
                                    // The owner will be temporarily set to `address(this)` inside the call.
                                    stor.owner = address(this);
                                    // Perform the migration.
                                    LibMigrate.delegatecallMigrateFunction(target, data);
                                    // Update the owner.
                                    stor.owner = newOwner;
                                    emit Migrated(msg.sender, target, newOwner);
                                }
                                /// @dev Get the owner of this contract.
                                /// @return owner_ The owner of this contract.
                                function owner() external override view returns (address owner_) {
                                    return LibOwnableStorage.getStorage().owner;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "./LibStorage.sol";
                            /// @dev Storage helpers for the `Ownable` feature.
                            library LibOwnableStorage {
                                /// @dev Storage bucket for this feature.
                                struct Storage {
                                    // The owner of this contract.
                                    address owner;
                                }
                                /// @dev Get the storage bucket for this contract.
                                function getStorage() internal pure returns (Storage storage stor) {
                                    uint256 storageSlot = LibStorage.getStorageSlot(
                                        LibStorage.StorageId.Ownable
                                    );
                                    // Dip into assembly to change the slot pointed to by the local
                                    // variable `stor`.
                                    // See https://solidity.readthedocs.io/en/v0.6.8/assembly.html?highlight=slot#access-to-external-variables-functions-and-libraries
                                    assembly { stor_slot := storageSlot }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "../fixins/FixinCommon.sol";
                            import "../storage/LibProxyStorage.sol";
                            import "../storage/LibSimpleFunctionRegistryStorage.sol";
                            import "../errors/LibSimpleFunctionRegistryRichErrors.sol";
                            import "../migrations/LibBootstrap.sol";
                            import "./IFeature.sol";
                            import "./ISimpleFunctionRegistry.sol";
                            /// @dev Basic registry management features.
                            contract SimpleFunctionRegistry is
                                IFeature,
                                ISimpleFunctionRegistry,
                                FixinCommon
                            {
                                // solhint-disable
                                string public constant override FEATURE_NAME = "SimpleFunctionRegistry";
                                /// @dev Version of this feature.
                                uint256 public immutable override FEATURE_VERSION = _encodeVersion(1, 0, 0);
                                using LibRichErrorsV06 for bytes;
                                constructor() public FixinCommon() {
                                    // solhint-disable-next-line no-empty-blocks
                                }
                                /// @dev Initializes this feature, registering its own functions.
                                /// @return success Magic bytes if successful.
                                function bootstrap()
                                    external
                                    returns (bytes4 success)
                                {
                                    // Register the registration functions (inception vibes).
                                    _extend(this.extend.selector, _implementation);
                                    _extend(this._extendSelf.selector, _implementation);
                                    // Register the rollback function.
                                    _extend(this.rollback.selector, _implementation);
                                    // Register getters.
                                    _extend(this.getRollbackLength.selector, _implementation);
                                    _extend(this.getRollbackEntryAtIndex.selector, _implementation);
                                    return LibBootstrap.BOOTSTRAP_SUCCESS;
                                }
                                /// @dev Roll back to a prior implementation of a function.
                                ///      Only directly callable by an authority.
                                /// @param selector The function selector.
                                /// @param targetImpl The address of an older implementation of the function.
                                function rollback(bytes4 selector, address targetImpl)
                                    external
                                    override
                                    onlyOwner
                                {
                                    (
                                        LibSimpleFunctionRegistryStorage.Storage storage stor,
                                        LibProxyStorage.Storage storage proxyStor
                                    ) = _getStorages();
                                    address currentImpl = proxyStor.impls[selector];
                                    if (currentImpl == targetImpl) {
                                        // Do nothing if already at targetImpl.
                                        return;
                                    }
                                    // Walk history backwards until we find the target implementation.
                                    address[] storage history = stor.implHistory[selector];
                                    uint256 i = history.length;
                                    for (; i > 0; --i) {
                                        address impl = history[i - 1];
                                        history.pop();
                                        if (impl == targetImpl) {
                                            break;
                                        }
                                    }
                                    if (i == 0) {
                                        LibSimpleFunctionRegistryRichErrors.NotInRollbackHistoryError(
                                            selector,
                                            targetImpl
                                        ).rrevert();
                                    }
                                    proxyStor.impls[selector] = targetImpl;
                                    emit ProxyFunctionUpdated(selector, currentImpl, targetImpl);
                                }
                                /// @dev Register or replace a function.
                                ///      Only directly callable by an authority.
                                /// @param selector The function selector.
                                /// @param impl The implementation contract for the function.
                                function extend(bytes4 selector, address impl)
                                    external
                                    override
                                    onlyOwner
                                {
                                    _extend(selector, impl);
                                }
                                /// @dev Register or replace a function.
                                ///      Only callable from within.
                                ///      This function is only used during the bootstrap process and
                                ///      should be deregistered by the deployer after bootstrapping is
                                ///      complete.
                                /// @param selector The function selector.
                                /// @param impl The implementation contract for the function.
                                function _extendSelf(bytes4 selector, address impl)
                                    external
                                    onlySelf
                                {
                                    _extend(selector, impl);
                                }
                                /// @dev Retrieve the length of the rollback history for a function.
                                /// @param selector The function selector.
                                /// @return rollbackLength The number of items in the rollback history for
                                ///         the function.
                                function getRollbackLength(bytes4 selector)
                                    external
                                    override
                                    view
                                    returns (uint256 rollbackLength)
                                {
                                    return LibSimpleFunctionRegistryStorage.getStorage().implHistory[selector].length;
                                }
                                /// @dev Retrieve an entry in the rollback history for a function.
                                /// @param selector The function selector.
                                /// @param idx The index in the rollback history.
                                /// @return impl An implementation address for the function at
                                ///         index `idx`.
                                function getRollbackEntryAtIndex(bytes4 selector, uint256 idx)
                                    external
                                    override
                                    view
                                    returns (address impl)
                                {
                                    return LibSimpleFunctionRegistryStorage.getStorage().implHistory[selector][idx];
                                }
                                /// @dev Register or replace a function.
                                /// @param selector The function selector.
                                /// @param impl The implementation contract for the function.
                                function _extend(bytes4 selector, address impl)
                                    private
                                {
                                    (
                                        LibSimpleFunctionRegistryStorage.Storage storage stor,
                                        LibProxyStorage.Storage storage proxyStor
                                    ) = _getStorages();
                                    address oldImpl = proxyStor.impls[selector];
                                    address[] storage history = stor.implHistory[selector];
                                    history.push(oldImpl);
                                    proxyStor.impls[selector] = impl;
                                    emit ProxyFunctionUpdated(selector, oldImpl, impl);
                                }
                                /// @dev Get the storage buckets for this feature and the proxy.
                                /// @return stor Storage bucket for this feature.
                                /// @return proxyStor age bucket for the proxy.
                                function _getStorages()
                                    private
                                    pure
                                    returns (
                                        LibSimpleFunctionRegistryStorage.Storage storage stor,
                                        LibProxyStorage.Storage storage proxyStor
                                    )
                                {
                                    return (
                                        LibSimpleFunctionRegistryStorage.getStorage(),
                                        LibProxyStorage.getStorage()
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "./LibStorage.sol";
                            /// @dev Storage helpers for the `SimpleFunctionRegistry` feature.
                            library LibSimpleFunctionRegistryStorage {
                                /// @dev Storage bucket for this feature.
                                struct Storage {
                                    // Mapping of function selector -> implementation history.
                                    mapping(bytes4 => address[]) implHistory;
                                }
                                /// @dev Get the storage bucket for this contract.
                                function getStorage() internal pure returns (Storage storage stor) {
                                    uint256 storageSlot = LibStorage.getStorageSlot(
                                        LibStorage.StorageId.SimpleFunctionRegistry
                                    );
                                    // Dip into assembly to change the slot pointed to by the local
                                    // variable `stor`.
                                    // See https://solidity.readthedocs.io/en/v0.6.8/assembly.html?highlight=slot#access-to-external-variables-functions-and-libraries
                                    assembly { stor_slot := storageSlot }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
                            import "../errors/LibSignatureRichErrors.sol";
                            import "../fixins/FixinCommon.sol";
                            import "../migrations/LibMigrate.sol";
                            import "./ISignatureValidator.sol";
                            import "./IFeature.sol";
                            /// @dev Feature for validating signatures.
                            contract SignatureValidator is
                                IFeature,
                                ISignatureValidator,
                                FixinCommon
                            {
                                using LibBytesV06 for bytes;
                                using LibRichErrorsV06 for bytes;
                                /// @dev Name of this feature.
                                string public constant override FEATURE_NAME = "SignatureValidator";
                                /// @dev Version of this feature.
                                uint256 public immutable override FEATURE_VERSION = _encodeVersion(1, 0, 0);
                                constructor() public FixinCommon() {
                                    // solhint-disable-next-line no-empty-blocks
                                }
                                /// @dev Initialize and register this feature.
                                ///      Should be delegatecalled by `Migrate.migrate()`.
                                /// @return success `LibMigrate.SUCCESS` on success.
                                function migrate()
                                    external
                                    returns (bytes4 success)
                                {
                                    _registerFeatureFunction(this.validateHashSignature.selector);
                                    _registerFeatureFunction(this.isValidHashSignature.selector);
                                    return LibMigrate.MIGRATE_SUCCESS;
                                }
                                /// @dev Validate that `hash` was signed by `signer` given `signature`.
                                ///      Reverts otherwise.
                                /// @param hash The hash that was signed.
                                /// @param signer The signer of the hash.
                                /// @param signature The signature. The last byte of this signature should
                                ///        be a member of the `SignatureType` enum.
                                function validateHashSignature(
                                    bytes32 hash,
                                    address signer,
                                    bytes memory signature
                                )
                                    public
                                    override
                                    view
                                {
                                    SignatureType signatureType = _readValidSignatureType(
                                        hash,
                                        signer,
                                        signature
                                    );
                                    // TODO: When we support non-hash signature types, assert that
                                    // `signatureType` is only `EIP712` or `EthSign` here.
                                    _validateHashSignatureTypes(
                                        signatureType,
                                        hash,
                                        signer,
                                        signature
                                    );
                                }
                                /// @dev Check that `hash` was signed by `signer` given `signature`.
                                /// @param hash The hash that was signed.
                                /// @param signer The signer of the hash.
                                /// @param signature The signature. The last byte of this signature should
                                ///        be a member of the `SignatureType` enum.
                                /// @return isValid `true` on success.
                                function isValidHashSignature(
                                    bytes32 hash,
                                    address signer,
                                    bytes calldata signature
                                )
                                    external
                                    view
                                    override
                                    returns (bool isValid)
                                {
                                    try this.validateHashSignature(hash, signer, signature) {
                                        isValid = true;
                                    } catch (bytes memory) {
                                        isValid = false;
                                    }
                                }
                                /// @dev Validates a hash-only signature type. Low-level, hidden variant.
                                /// @param signatureType The type of signature to check.
                                /// @param hash The hash that was signed.
                                /// @param signer The signer of the hash.
                                /// @param signature The signature. The last byte of this signature should
                                ///        be a member of the `SignatureType` enum.
                                function _validateHashSignatureTypes(
                                    SignatureType signatureType,
                                    bytes32 hash,
                                    address signer,
                                    bytes memory signature
                                )
                                    private
                                    pure
                                {
                                    address recovered = address(0);
                                    if (signatureType == SignatureType.Invalid) {
                                        // Always invalid signature.
                                        // Like Illegal, this is always implicitly available and therefore
                                        // offered explicitly. It can be implicitly created by providing
                                        // a correctly formatted but incorrect signature.
                                        LibSignatureRichErrors.SignatureValidationError(
                                            LibSignatureRichErrors.SignatureValidationErrorCodes.ALWAYS_INVALID,
                                            hash,
                                            signer,
                                            signature
                                        ).rrevert();
                                    } else if (signatureType == SignatureType.EIP712) {
                                        // Signature using EIP712
                                        if (signature.length != 66) {
                                            LibSignatureRichErrors.SignatureValidationError(
                                                LibSignatureRichErrors.SignatureValidationErrorCodes.INVALID_LENGTH,
                                                hash,
                                                signer,
                                                signature
                                            ).rrevert();
                                        }
                                        uint8 v = uint8(signature[0]);
                                        bytes32 r = signature.readBytes32(1);
                                        bytes32 s = signature.readBytes32(33);
                                        recovered = ecrecover(
                                            hash,
                                            v,
                                            r,
                                            s
                                        );
                                    } else if (signatureType == SignatureType.EthSign) {
                                        // Signed using `eth_sign`
                                        if (signature.length != 66) {
                                            LibSignatureRichErrors.SignatureValidationError(
                                                LibSignatureRichErrors.SignatureValidationErrorCodes.INVALID_LENGTH,
                                                hash,
                                                signer,
                                                signature
                                            ).rrevert();
                                        }
                                        uint8 v = uint8(signature[0]);
                                        bytes32 r = signature.readBytes32(1);
                                        bytes32 s = signature.readBytes32(33);
                                        recovered = ecrecover(
                                            keccak256(abi.encodePacked(
                                                "\\x19Ethereum Signed Message:\
                            32",
                                                hash
                                            )),
                                            v,
                                            r,
                                            s
                                        );
                                    } else {
                                        // This should never happen.
                                        revert('SignatureValidator/ILLEGAL_CODE_PATH');
                                    }
                                    if (recovered == address(0) || signer != recovered) {
                                        LibSignatureRichErrors.SignatureValidationError(
                                            LibSignatureRichErrors.SignatureValidationErrorCodes.WRONG_SIGNER,
                                            hash,
                                            signer,
                                            signature
                                        ).rrevert();
                                    }
                                }
                                /// @dev Reads the `SignatureType` from the end of a signature and validates it.
                                function _readValidSignatureType(
                                    bytes32 hash,
                                    address signer,
                                    bytes memory signature
                                )
                                    private
                                    pure
                                    returns (SignatureType signatureType)
                                {
                                    // Read the signatureType from the signature
                                    signatureType = _readSignatureType(
                                        hash,
                                        signer,
                                        signature
                                    );
                                    // Ensure signature is supported
                                    if (uint8(signatureType) >= uint8(SignatureType.NSignatureTypes)) {
                                        LibSignatureRichErrors.SignatureValidationError(
                                            LibSignatureRichErrors.SignatureValidationErrorCodes.UNSUPPORTED,
                                            hash,
                                            signer,
                                            signature
                                        ).rrevert();
                                    }
                                    // Always illegal signature.
                                    // This is always an implicit option since a signer can create a
                                    // signature array with invalid type or length. We may as well make
                                    // it an explicit option. This aids testing and analysis. It is
                                    // also the initialization value for the enum type.
                                    if (signatureType == SignatureType.Illegal) {
                                        LibSignatureRichErrors.SignatureValidationError(
                                            LibSignatureRichErrors.SignatureValidationErrorCodes.ILLEGAL,
                                            hash,
                                            signer,
                                            signature
                                        ).rrevert();
                                    }
                                }
                                /// @dev Reads the `SignatureType` from the end of a signature.
                                function _readSignatureType(
                                    bytes32 hash,
                                    address signer,
                                    bytes memory signature
                                )
                                    private
                                    pure
                                    returns (SignatureType sigType)
                                {
                                    if (signature.length == 0) {
                                        LibSignatureRichErrors.SignatureValidationError(
                                            LibSignatureRichErrors.SignatureValidationErrorCodes.INVALID_LENGTH,
                                            hash,
                                            signer,
                                            signature
                                        ).rrevert();
                                    }
                                    return SignatureType(uint8(signature[signature.length - 1]));
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
                            import "../errors/LibSpenderRichErrors.sol";
                            import "../fixins/FixinCommon.sol";
                            import "../migrations/LibMigrate.sol";
                            import "../external/IAllowanceTarget.sol";
                            import "../storage/LibTokenSpenderStorage.sol";
                            import "./ITokenSpender.sol";
                            import "./IFeature.sol";
                            import "./ISimpleFunctionRegistry.sol";
                            /// @dev Feature that allows spending token allowances.
                            contract TokenSpender is
                                IFeature,
                                ITokenSpender,
                                FixinCommon
                            {
                                // solhint-disable
                                /// @dev Name of this feature.
                                string public constant override FEATURE_NAME = "TokenSpender";
                                /// @dev Version of this feature.
                                uint256 public immutable override FEATURE_VERSION = _encodeVersion(1, 0, 0);
                                // solhint-enable
                                using LibRichErrorsV06 for bytes;
                                constructor() public FixinCommon() {
                                    // solhint-disable-next-line no-empty-blocks
                                }
                                /// @dev Initialize and register this feature. Should be delegatecalled
                                ///      into during a `Migrate.migrate()`.
                                /// @param allowanceTarget An `allowanceTarget` instance, configured to have
                                ///        the ZeroeEx contract as an authority.
                                /// @return success `MIGRATE_SUCCESS` on success.
                                function migrate(IAllowanceTarget allowanceTarget)
                                    external
                                    returns (bytes4 success)
                                {
                                    LibTokenSpenderStorage.getStorage().allowanceTarget = allowanceTarget;
                                    _registerFeatureFunction(this.getAllowanceTarget.selector);
                                    _registerFeatureFunction(this._spendERC20Tokens.selector);
                                    _registerFeatureFunction(this.getSpendableERC20BalanceOf.selector);
                                    return LibMigrate.MIGRATE_SUCCESS;
                                }
                                /// @dev Transfers ERC20 tokens from `owner` to `to`. Only callable from within.
                                /// @param token The token to spend.
                                /// @param owner The owner of the tokens.
                                /// @param to The recipient of the tokens.
                                /// @param amount The amount of `token` to transfer.
                                function _spendERC20Tokens(
                                    IERC20TokenV06 token,
                                    address owner,
                                    address to,
                                    uint256 amount
                                )
                                    external
                                    override
                                    onlySelf
                                {
                                    IAllowanceTarget spender = LibTokenSpenderStorage.getStorage().allowanceTarget;
                                    // Have the allowance target execute an ERC20 `transferFrom()`.
                                    (bool didSucceed, bytes memory resultData) = address(spender).call(
                                        abi.encodeWithSelector(
                                            IAllowanceTarget.executeCall.selector,
                                            address(token),
                                            abi.encodeWithSelector(
                                                IERC20TokenV06.transferFrom.selector,
                                                owner,
                                                to,
                                                amount
                                            )
                                        )
                                    );
                                    if (didSucceed) {
                                        resultData = abi.decode(resultData, (bytes));
                                    }
                                    if (!didSucceed || !LibERC20TokenV06.isSuccessfulResult(resultData)) {
                                        LibSpenderRichErrors.SpenderERC20TransferFromFailedError(
                                            address(token),
                                            owner,
                                            to,
                                            amount,
                                            resultData
                                        ).rrevert();
                                    }
                                }
                                /// @dev Gets the maximum amount of an ERC20 token `token` that can be
                                ///      pulled from `owner` by the token spender.
                                /// @param token The token to spend.
                                /// @param owner The owner of the tokens.
                                /// @return amount The amount of tokens that can be pulled.
                                function getSpendableERC20BalanceOf(IERC20TokenV06 token, address owner)
                                    external
                                    override
                                    view
                                    returns (uint256 amount)
                                {
                                    return LibSafeMathV06.min256(
                                        token.allowance(owner, address(LibTokenSpenderStorage.getStorage().allowanceTarget)),
                                        token.balanceOf(owner)
                                    );
                                }
                                /// @dev Get the address of the allowance target.
                                /// @return target The target of token allowances.
                                function getAllowanceTarget()
                                    external
                                    override
                                    view
                                    returns (address target)
                                {
                                    return address(LibTokenSpenderStorage.getStorage().allowanceTarget);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./errors/LibRichErrorsV06.sol";
                            import "./errors/LibSafeMathRichErrorsV06.sol";
                            library LibSafeMathV06 {
                                function safeMul(uint256 a, uint256 b)
                                    internal
                                    pure
                                    returns (uint256)
                                {
                                    if (a == 0) {
                                        return 0;
                                    }
                                    uint256 c = a * b;
                                    if (c / a != b) {
                                        LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                                            LibSafeMathRichErrorsV06.BinOpErrorCodes.MULTIPLICATION_OVERFLOW,
                                            a,
                                            b
                                        ));
                                    }
                                    return c;
                                }
                                function safeDiv(uint256 a, uint256 b)
                                    internal
                                    pure
                                    returns (uint256)
                                {
                                    if (b == 0) {
                                        LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                                            LibSafeMathRichErrorsV06.BinOpErrorCodes.DIVISION_BY_ZERO,
                                            a,
                                            b
                                        ));
                                    }
                                    uint256 c = a / b;
                                    return c;
                                }
                                function safeSub(uint256 a, uint256 b)
                                    internal
                                    pure
                                    returns (uint256)
                                {
                                    if (b > a) {
                                        LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                                            LibSafeMathRichErrorsV06.BinOpErrorCodes.SUBTRACTION_UNDERFLOW,
                                            a,
                                            b
                                        ));
                                    }
                                    return a - b;
                                }
                                function safeAdd(uint256 a, uint256 b)
                                    internal
                                    pure
                                    returns (uint256)
                                {
                                    uint256 c = a + b;
                                    if (c < a) {
                                        LibRichErrorsV06.rrevert(LibSafeMathRichErrorsV06.Uint256BinOpError(
                                            LibSafeMathRichErrorsV06.BinOpErrorCodes.ADDITION_OVERFLOW,
                                            a,
                                            b
                                        ));
                                    }
                                    return c;
                                }
                                function max256(uint256 a, uint256 b)
                                    internal
                                    pure
                                    returns (uint256)
                                {
                                    return a >= b ? a : b;
                                }
                                function min256(uint256 a, uint256 b)
                                    internal
                                    pure
                                    returns (uint256)
                                {
                                    return a < b ? a : b;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibSafeMathRichErrorsV06 {
                                // bytes4(keccak256("Uint256BinOpError(uint8,uint256,uint256)"))
                                bytes4 internal constant UINT256_BINOP_ERROR_SELECTOR =
                                    0xe946c1bb;
                                // bytes4(keccak256("Uint256DowncastError(uint8,uint256)"))
                                bytes4 internal constant UINT256_DOWNCAST_ERROR_SELECTOR =
                                    0xc996af7b;
                                enum BinOpErrorCodes {
                                    ADDITION_OVERFLOW,
                                    MULTIPLICATION_OVERFLOW,
                                    SUBTRACTION_UNDERFLOW,
                                    DIVISION_BY_ZERO
                                }
                                enum DowncastErrorCodes {
                                    VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT32,
                                    VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT64,
                                    VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT96
                                }
                                // solhint-disable func-name-mixedcase
                                function Uint256BinOpError(
                                    BinOpErrorCodes errorCode,
                                    uint256 a,
                                    uint256 b
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        UINT256_BINOP_ERROR_SELECTOR,
                                        errorCode,
                                        a,
                                        b
                                    );
                                }
                                function Uint256DowncastError(
                                    DowncastErrorCodes errorCode,
                                    uint256 a
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        UINT256_DOWNCAST_ERROR_SELECTOR,
                                        errorCode,
                                        a
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
                            import "./IERC20TokenV06.sol";
                            library LibERC20TokenV06 {
                                bytes constant private DECIMALS_CALL_DATA = hex"313ce567";
                                /// @dev Calls `IERC20TokenV06(token).approve()`.
                                ///      Reverts if the result fails `isSuccessfulResult()` or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param spender The address that receives an allowance.
                                /// @param allowance The allowance to set.
                                function compatApprove(
                                    IERC20TokenV06 token,
                                    address spender,
                                    uint256 allowance
                                )
                                    internal
                                {
                                    bytes memory callData = abi.encodeWithSelector(
                                        token.approve.selector,
                                        spender,
                                        allowance
                                    );
                                    _callWithOptionalBooleanResult(address(token), callData);
                                }
                                /// @dev Calls `IERC20TokenV06(token).approve()` and sets the allowance to the
                                ///      maximum if the current approval is not already >= an amount.
                                ///      Reverts if the result fails `isSuccessfulResult()` or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param spender The address that receives an allowance.
                                /// @param amount The minimum allowance needed.
                                function approveIfBelow(
                                    IERC20TokenV06 token,
                                    address spender,
                                    uint256 amount
                                )
                                    internal
                                {
                                    if (token.allowance(address(this), spender) < amount) {
                                        compatApprove(token, spender, uint256(-1));
                                    }
                                }
                                /// @dev Calls `IERC20TokenV06(token).transfer()`.
                                ///      Reverts if the result fails `isSuccessfulResult()` or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param to The address that receives the tokens
                                /// @param amount Number of tokens to transfer.
                                function compatTransfer(
                                    IERC20TokenV06 token,
                                    address to,
                                    uint256 amount
                                )
                                    internal
                                {
                                    bytes memory callData = abi.encodeWithSelector(
                                        token.transfer.selector,
                                        to,
                                        amount
                                    );
                                    _callWithOptionalBooleanResult(address(token), callData);
                                }
                                /// @dev Calls `IERC20TokenV06(token).transferFrom()`.
                                ///      Reverts if the result fails `isSuccessfulResult()` or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param from The owner of the tokens.
                                /// @param to The address that receives the tokens
                                /// @param amount Number of tokens to transfer.
                                function compatTransferFrom(
                                    IERC20TokenV06 token,
                                    address from,
                                    address to,
                                    uint256 amount
                                )
                                    internal
                                {
                                    bytes memory callData = abi.encodeWithSelector(
                                        token.transferFrom.selector,
                                        from,
                                        to,
                                        amount
                                    );
                                    _callWithOptionalBooleanResult(address(token), callData);
                                }
                                /// @dev Retrieves the number of decimals for a token.
                                ///      Returns `18` if the call reverts.
                                /// @param token The address of the token contract.
                                /// @return tokenDecimals The number of decimals places for the token.
                                function compatDecimals(IERC20TokenV06 token)
                                    internal
                                    view
                                    returns (uint8 tokenDecimals)
                                {
                                    tokenDecimals = 18;
                                    (bool didSucceed, bytes memory resultData) = address(token).staticcall(DECIMALS_CALL_DATA);
                                    if (didSucceed && resultData.length == 32) {
                                        tokenDecimals = uint8(LibBytesV06.readUint256(resultData, 0));
                                    }
                                }
                                /// @dev Retrieves the allowance for a token, owner, and spender.
                                ///      Returns `0` if the call reverts.
                                /// @param token The address of the token contract.
                                /// @param owner The owner of the tokens.
                                /// @param spender The address the spender.
                                /// @return allowance_ The allowance for a token, owner, and spender.
                                function compatAllowance(IERC20TokenV06 token, address owner, address spender)
                                    internal
                                    view
                                    returns (uint256 allowance_)
                                {
                                    (bool didSucceed, bytes memory resultData) = address(token).staticcall(
                                        abi.encodeWithSelector(
                                            token.allowance.selector,
                                            owner,
                                            spender
                                        )
                                    );
                                    if (didSucceed && resultData.length == 32) {
                                        allowance_ = LibBytesV06.readUint256(resultData, 0);
                                    }
                                }
                                /// @dev Retrieves the balance for a token owner.
                                ///      Returns `0` if the call reverts.
                                /// @param token The address of the token contract.
                                /// @param owner The owner of the tokens.
                                /// @return balance The token balance of an owner.
                                function compatBalanceOf(IERC20TokenV06 token, address owner)
                                    internal
                                    view
                                    returns (uint256 balance)
                                {
                                    (bool didSucceed, bytes memory resultData) = address(token).staticcall(
                                        abi.encodeWithSelector(
                                            token.balanceOf.selector,
                                            owner
                                        )
                                    );
                                    if (didSucceed && resultData.length == 32) {
                                        balance = LibBytesV06.readUint256(resultData, 0);
                                    }
                                }
                                /// @dev Check if the data returned by a non-static call to an ERC20 token
                                ///      is a successful result. Supported functions are `transfer()`,
                                ///      `transferFrom()`, and `approve()`.
                                /// @param resultData The raw data returned by a non-static call to the ERC20 token.
                                /// @return isSuccessful Whether the result data indicates success.
                                function isSuccessfulResult(bytes memory resultData)
                                    internal
                                    pure
                                    returns (bool isSuccessful)
                                {
                                    if (resultData.length == 0) {
                                        return true;
                                    }
                                    if (resultData.length == 32) {
                                        uint256 result = LibBytesV06.readUint256(resultData, 0);
                                        if (result == 1) {
                                            return true;
                                        }
                                    }
                                }
                                /// @dev Executes a call on address `target` with calldata `callData`
                                ///      and asserts that either nothing was returned or a single boolean
                                ///      was returned equal to `true`.
                                /// @param target The call target.
                                /// @param callData The abi-encoded call data.
                                function _callWithOptionalBooleanResult(
                                    address target,
                                    bytes memory callData
                                )
                                    private
                                {
                                    (bool didSucceed, bytes memory resultData) = target.call(callData);
                                    if (didSucceed && isSuccessfulResult(resultData)) {
                                        return;
                                    }
                                    LibRichErrorsV06.rrevert(resultData);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "./LibStorage.sol";
                            import "../external/IAllowanceTarget.sol";
                            /// @dev Storage helpers for the `TokenSpender` feature.
                            library LibTokenSpenderStorage {
                                /// @dev Storage bucket for this feature.
                                struct Storage {
                                    // Allowance target contract.
                                    IAllowanceTarget allowanceTarget;
                                }
                                /// @dev Get the storage bucket for this contract.
                                function getStorage() internal pure returns (Storage storage stor) {
                                    uint256 storageSlot = LibStorage.getStorageSlot(
                                        LibStorage.StorageId.TokenSpender
                                    );
                                    // Dip into assembly to change the slot pointed to by the local
                                    // variable `stor`.
                                    // See https://solidity.readthedocs.io/en/v0.6.8/assembly.html?highlight=slot#access-to-external-variables-functions-and-libraries
                                    assembly { stor_slot := storageSlot }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            import "../errors/LibTransformERC20RichErrors.sol";
                            import "../fixins/FixinCommon.sol";
                            import "../migrations/LibMigrate.sol";
                            import "../external/IFlashWallet.sol";
                            import "../external/FlashWallet.sol";
                            import "../storage/LibTransformERC20Storage.sol";
                            import "../transformers/IERC20Transformer.sol";
                            import "../transformers/LibERC20Transformer.sol";
                            import "./ITransformERC20.sol";
                            import "./ITokenSpender.sol";
                            import "./IFeature.sol";
                            import "./ISimpleFunctionRegistry.sol";
                            /// @dev Feature to composably transform between ERC20 tokens.
                            contract TransformERC20 is
                                IFeature,
                                ITransformERC20,
                                FixinCommon
                            {
                                /// @dev Stack vars for `_transformERC20Private()`.
                                struct TransformERC20PrivateState {
                                    IFlashWallet wallet;
                                    address transformerDeployer;
                                    uint256 takerOutputTokenBalanceBefore;
                                    uint256 takerOutputTokenBalanceAfter;
                                }
                                /// @dev Name of this feature.
                                string public constant override FEATURE_NAME = "TransformERC20";
                                /// @dev Version of this feature.
                                uint256 public immutable override FEATURE_VERSION = _encodeVersion(1, 1, 0);
                                using LibSafeMathV06 for uint256;
                                using LibRichErrorsV06 for bytes;
                                constructor() public FixinCommon() {
                                    // solhint-disable-next-line no-empty-blocks
                                }
                                /// @dev Initialize and register this feature.
                                ///      Should be delegatecalled by `Migrate.migrate()`.
                                /// @param transformerDeployer The trusted deployer for transformers.
                                /// @return success `LibMigrate.SUCCESS` on success.
                                function migrate(address transformerDeployer)
                                    external
                                    returns (bytes4 success)
                                {
                                    _registerFeatureFunction(this.getTransformerDeployer.selector);
                                    _registerFeatureFunction(this.createTransformWallet.selector);
                                    _registerFeatureFunction(this.getTransformWallet.selector);
                                    _registerFeatureFunction(this.setTransformerDeployer.selector);
                                    _registerFeatureFunction(this.transformERC20.selector);
                                    _registerFeatureFunction(this._transformERC20.selector);
                                    this.createTransformWallet();
                                    LibTransformERC20Storage.getStorage().transformerDeployer = transformerDeployer;
                                    return LibMigrate.MIGRATE_SUCCESS;
                                }
                                /// @dev Replace the allowed deployer for transformers.
                                ///      Only callable by the owner.
                                /// @param transformerDeployer The address of the trusted deployer for transformers.
                                function setTransformerDeployer(address transformerDeployer)
                                    external
                                    override
                                    onlyOwner
                                {
                                    LibTransformERC20Storage.getStorage().transformerDeployer = transformerDeployer;
                                    emit TransformerDeployerUpdated(transformerDeployer);
                                }
                                /// @dev Return the allowed deployer for transformers.
                                /// @return deployer The transform deployer address.
                                function getTransformerDeployer()
                                    public
                                    override
                                    view
                                    returns (address deployer)
                                {
                                    return LibTransformERC20Storage.getStorage().transformerDeployer;
                                }
                                /// @dev Deploy a new wallet instance and replace the current one with it.
                                ///      Useful if we somehow break the current wallet instance.
                                ///      Only callable by the owner.
                                /// @return wallet The new wallet instance.
                                function createTransformWallet()
                                    public
                                    override
                                    onlyOwner
                                    returns (IFlashWallet wallet)
                                {
                                    wallet = new FlashWallet();
                                    LibTransformERC20Storage.getStorage().wallet = wallet;
                                }
                                /// @dev Executes a series of transformations to convert an ERC20 `inputToken`
                                ///      to an ERC20 `outputToken`.
                                /// @param inputToken The token being provided by the sender.
                                ///        If `0xeee...`, ETH is implied and should be provided with the call.`
                                /// @param outputToken The token to be acquired by the sender.
                                ///        `0xeee...` implies ETH.
                                /// @param inputTokenAmount The amount of `inputToken` to take from the sender.
                                ///        If set to `uint256(-1)`, the entire spendable balance of the taker
                                ///        will be solt.
                                /// @param minOutputTokenAmount The minimum amount of `outputToken` the sender
                                ///        must receive for the entire transformation to succeed. If set to zero,
                                ///        the minimum output token transfer will not be asserted.
                                /// @param transformations The transformations to execute on the token balance(s)
                                ///        in sequence.
                                /// @return outputTokenAmount The amount of `outputToken` received by the sender.
                                function transformERC20(
                                    IERC20TokenV06 inputToken,
                                    IERC20TokenV06 outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 minOutputTokenAmount,
                                    Transformation[] memory transformations
                                )
                                    public
                                    override
                                    payable
                                    returns (uint256 outputTokenAmount)
                                {
                                    return _transformERC20Private(
                                        keccak256(msg.data),
                                        msg.sender,
                                        inputToken,
                                        outputToken,
                                        inputTokenAmount,
                                        minOutputTokenAmount,
                                        transformations
                                    );
                                }
                                /// @dev Internal version of `transformERC20()`. Only callable from within.
                                /// @param callDataHash Hash of the ingress calldata.
                                /// @param taker The taker address.
                                /// @param inputToken The token being provided by the taker.
                                ///        If `0xeee...`, ETH is implied and should be provided with the call.`
                                /// @param outputToken The token to be acquired by the taker.
                                ///        `0xeee...` implies ETH.
                                /// @param inputTokenAmount The amount of `inputToken` to take from the taker.
                                ///        If set to `uint256(-1)`, the entire spendable balance of the taker
                                ///        will be solt.
                                /// @param minOutputTokenAmount The minimum amount of `outputToken` the taker
                                ///        must receive for the entire transformation to succeed. If set to zero,
                                ///        the minimum output token transfer will not be asserted.
                                /// @param transformations The transformations to execute on the token balance(s)
                                ///        in sequence.
                                /// @return outputTokenAmount The amount of `outputToken` received by the taker.
                                function _transformERC20(
                                    bytes32 callDataHash,
                                    address payable taker,
                                    IERC20TokenV06 inputToken,
                                    IERC20TokenV06 outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 minOutputTokenAmount,
                                    Transformation[] memory transformations
                                )
                                    public
                                    virtual
                                    override
                                    payable
                                    onlySelf
                                    returns (uint256 outputTokenAmount)
                                {
                                    return _transformERC20Private(
                                        callDataHash,
                                        taker,
                                        inputToken,
                                        outputToken,
                                        inputTokenAmount,
                                        minOutputTokenAmount,
                                        transformations
                                    );
                                }
                                /// @dev Private version of `transformERC20()`.
                                /// @param callDataHash Hash of the ingress calldata.
                                /// @param taker The taker address.
                                /// @param inputToken The token being provided by the taker.
                                ///        If `0xeee...`, ETH is implied and should be provided with the call.`
                                /// @param outputToken The token to be acquired by the taker.
                                ///        `0xeee...` implies ETH.
                                /// @param inputTokenAmount The amount of `inputToken` to take from the taker.
                                ///        If set to `uint256(-1)`, the entire spendable balance of the taker
                                ///        will be solt.
                                /// @param minOutputTokenAmount The minimum amount of `outputToken` the taker
                                ///        must receive for the entire transformation to succeed. If set to zero,
                                ///        the minimum output token transfer will not be asserted.
                                /// @param transformations The transformations to execute on the token balance(s)
                                ///        in sequence.
                                /// @return outputTokenAmount The amount of `outputToken` received by the taker.
                                function _transformERC20Private(
                                    bytes32 callDataHash,
                                    address payable taker,
                                    IERC20TokenV06 inputToken,
                                    IERC20TokenV06 outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 minOutputTokenAmount,
                                    Transformation[] memory transformations
                                )
                                    private
                                    returns (uint256 outputTokenAmount)
                                {
                                    // If the input token amount is -1, transform the taker's entire
                                    // spendable balance.
                                    if (inputTokenAmount == uint256(-1)) {
                                        inputTokenAmount = ITokenSpender(address(this))
                                            .getSpendableERC20BalanceOf(inputToken, taker);
                                    }
                                    TransformERC20PrivateState memory state;
                                    state.wallet = getTransformWallet();
                                    state.transformerDeployer = getTransformerDeployer();
                                    // Remember the initial output token balance of the taker.
                                    state.takerOutputTokenBalanceBefore =
                                        LibERC20Transformer.getTokenBalanceOf(outputToken, taker);
                                    // Pull input tokens from the taker to the wallet and transfer attached ETH.
                                    _transferInputTokensAndAttachedEth(
                                        inputToken,
                                        taker,
                                        address(state.wallet),
                                        inputTokenAmount
                                    );
                                    // Perform transformations.
                                    for (uint256 i = 0; i < transformations.length; ++i) {
                                        _executeTransformation(
                                            state.wallet,
                                            transformations[i],
                                            state.transformerDeployer,
                                            taker,
                                            callDataHash
                                        );
                                    }
                                    // Compute how much output token has been transferred to the taker.
                                    state.takerOutputTokenBalanceAfter =
                                        LibERC20Transformer.getTokenBalanceOf(outputToken, taker);
                                    if (state.takerOutputTokenBalanceAfter > state.takerOutputTokenBalanceBefore) {
                                        outputTokenAmount = state.takerOutputTokenBalanceAfter.safeSub(
                                            state.takerOutputTokenBalanceBefore
                                        );
                                    } else if (state.takerOutputTokenBalanceAfter < state.takerOutputTokenBalanceBefore) {
                                        LibTransformERC20RichErrors.NegativeTransformERC20OutputError(
                                            address(outputToken),
                                            state.takerOutputTokenBalanceBefore - state.takerOutputTokenBalanceAfter
                                        ).rrevert();
                                    }
                                    // Ensure enough output token has been sent to the taker.
                                    if (outputTokenAmount < minOutputTokenAmount) {
                                        LibTransformERC20RichErrors.IncompleteTransformERC20Error(
                                            address(outputToken),
                                            outputTokenAmount,
                                            minOutputTokenAmount
                                        ).rrevert();
                                    }
                                    // Emit an event.
                                    emit TransformedERC20(
                                        taker,
                                        address(inputToken),
                                        address(outputToken),
                                        inputTokenAmount,
                                        outputTokenAmount
                                    );
                                }
                                /// @dev Return the current wallet instance that will serve as the execution
                                ///      context for transformations.
                                /// @return wallet The wallet instance.
                                function getTransformWallet()
                                    public
                                    override
                                    view
                                    returns (IFlashWallet wallet)
                                {
                                    return LibTransformERC20Storage.getStorage().wallet;
                                }
                                /// @dev Transfer input tokens from the taker and any attached ETH to `to`
                                /// @param inputToken The token to pull from the taker.
                                /// @param from The from (taker) address.
                                /// @param to The recipient of tokens and ETH.
                                /// @param amount Amount of `inputToken` tokens to transfer.
                                function _transferInputTokensAndAttachedEth(
                                    IERC20TokenV06 inputToken,
                                    address from,
                                    address payable to,
                                    uint256 amount
                                )
                                    private
                                {
                                    // Transfer any attached ETH.
                                    if (msg.value != 0) {
                                        to.transfer(msg.value);
                                    }
                                    // Transfer input tokens.
                                    if (!LibERC20Transformer.isTokenETH(inputToken)) {
                                        // Token is not ETH, so pull ERC20 tokens.
                                        ITokenSpender(address(this))._spendERC20Tokens(
                                            inputToken,
                                            from,
                                            to,
                                            amount
                                        );
                                    } else if (msg.value < amount) {
                                         // Token is ETH, so the caller must attach enough ETH to the call.
                                        LibTransformERC20RichErrors.InsufficientEthAttachedError(
                                            msg.value,
                                            amount
                                        ).rrevert();
                                    }
                                }
                                /// @dev Executs a transformer in the context of `wallet`.
                                /// @param wallet The wallet instance.
                                /// @param transformation The transformation.
                                /// @param transformerDeployer The address of the transformer deployer.
                                /// @param taker The taker address.
                                /// @param callDataHash Hash of the calldata.
                                function _executeTransformation(
                                    IFlashWallet wallet,
                                    Transformation memory transformation,
                                    address transformerDeployer,
                                    address payable taker,
                                    bytes32 callDataHash
                                )
                                    private
                                {
                                    // Derive the transformer address from the deployment nonce.
                                    address payable transformer = LibERC20Transformer.getDeployedAddress(
                                        transformerDeployer,
                                        transformation.deploymentNonce
                                    );
                                    // Call `transformer.transform()` as the wallet.
                                    bytes memory resultData = wallet.executeDelegateCall(
                                        // The call target.
                                        transformer,
                                        // Call data.
                                        abi.encodeWithSelector(
                                            IERC20Transformer.transform.selector,
                                            callDataHash,
                                            taker,
                                            transformation.data
                                        )
                                    );
                                    // Ensure the transformer returned the magic bytes.
                                    if (resultData.length != 32 ||
                                        abi.decode(resultData, (bytes4)) != LibERC20Transformer.TRANSFORMER_SUCCESS
                                    ) {
                                        LibTransformERC20RichErrors.TransformerFailedError(
                                            transformer,
                                            transformation.data,
                                            resultData
                                        ).rrevert();
                                    }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "./LibStorage.sol";
                            import "../external/IFlashWallet.sol";
                            /// @dev Storage helpers for the `TransformERC20` feature.
                            library LibTransformERC20Storage {
                                /// @dev Storage bucket for this feature.
                                struct Storage {
                                    // The current wallet instance.
                                    IFlashWallet wallet;
                                    // The transformer deployer address.
                                    address transformerDeployer;
                                }
                                /// @dev Get the storage bucket for this contract.
                                function getStorage() internal pure returns (Storage storage stor) {
                                    uint256 storageSlot = LibStorage.getStorageSlot(
                                        LibStorage.StorageId.TransformERC20
                                    );
                                    // Dip into assembly to change the slot pointed to by the local
                                    // variable `stor`.
                                    // See https://solidity.readthedocs.io/en/v0.6.8/assembly.html?highlight=slot#access-to-external-variables-functions-and-libraries
                                    assembly { stor_slot := storageSlot }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
                            library LibERC20Transformer {
                                using LibERC20TokenV06 for IERC20TokenV06;
                                /// @dev ETH pseudo-token address.
                                address constant internal ETH_TOKEN_ADDRESS = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
                                /// @dev Return value indicating success in `IERC20Transformer.transform()`.
                                ///      This is just `keccak256('TRANSFORMER_SUCCESS')`.
                                bytes4 constant internal TRANSFORMER_SUCCESS = 0x13c9929e;
                                /// @dev Transfer ERC20 tokens and ETH.
                                /// @param token An ERC20 or the ETH pseudo-token address (`ETH_TOKEN_ADDRESS`).
                                /// @param to The recipient.
                                /// @param amount The transfer amount.
                                function transformerTransfer(
                                    IERC20TokenV06 token,
                                    address payable to,
                                    uint256 amount
                                )
                                    internal
                                {
                                    if (isTokenETH(token)) {
                                        to.transfer(amount);
                                    } else {
                                        token.compatTransfer(to, amount);
                                    }
                                }
                                /// @dev Check if a token is the ETH pseudo-token.
                                /// @param token The token to check.
                                /// @return isETH `true` if the token is the ETH pseudo-token.
                                function isTokenETH(IERC20TokenV06 token)
                                    internal
                                    pure
                                    returns (bool isETH)
                                {
                                    return address(token) == ETH_TOKEN_ADDRESS;
                                }
                                /// @dev Check the balance of an ERC20 token or ETH.
                                /// @param token An ERC20 or the ETH pseudo-token address (`ETH_TOKEN_ADDRESS`).
                                /// @param owner Holder of the tokens.
                                /// @return tokenBalance The balance of `owner`.
                                function getTokenBalanceOf(IERC20TokenV06 token, address owner)
                                    internal
                                    view
                                    returns (uint256 tokenBalance)
                                {
                                    if (isTokenETH(token)) {
                                        return owner.balance;
                                    }
                                    return token.balanceOf(owner);
                                }
                                /// @dev RLP-encode a 32-bit or less account nonce.
                                /// @param nonce A positive integer in the range 0 <= nonce < 2^32.
                                /// @return rlpNonce The RLP encoding.
                                function rlpEncodeNonce(uint32 nonce)
                                    internal
                                    pure
                                    returns (bytes memory rlpNonce)
                                {
                                    // See https://github.com/ethereum/wiki/wiki/RLP for RLP encoding rules.
                                    if (nonce == 0) {
                                        rlpNonce = new bytes(1);
                                        rlpNonce[0] = 0x80;
                                    } else if (nonce < 0x80) {
                                        rlpNonce = new bytes(1);
                                        rlpNonce[0] = byte(uint8(nonce));
                                    } else if (nonce <= 0xFF) {
                                        rlpNonce = new bytes(2);
                                        rlpNonce[0] = 0x81;
                                        rlpNonce[1] = byte(uint8(nonce));
                                    } else if (nonce <= 0xFFFF) {
                                        rlpNonce = new bytes(3);
                                        rlpNonce[0] = 0x82;
                                        rlpNonce[1] = byte(uint8((nonce & 0xFF00) >> 8));
                                        rlpNonce[2] = byte(uint8(nonce));
                                    } else if (nonce <= 0xFFFFFF) {
                                        rlpNonce = new bytes(4);
                                        rlpNonce[0] = 0x83;
                                        rlpNonce[1] = byte(uint8((nonce & 0xFF0000) >> 16));
                                        rlpNonce[2] = byte(uint8((nonce & 0xFF00) >> 8));
                                        rlpNonce[3] = byte(uint8(nonce));
                                    } else {
                                        rlpNonce = new bytes(5);
                                        rlpNonce[0] = 0x84;
                                        rlpNonce[1] = byte(uint8((nonce & 0xFF000000) >> 24));
                                        rlpNonce[2] = byte(uint8((nonce & 0xFF0000) >> 16));
                                        rlpNonce[3] = byte(uint8((nonce & 0xFF00) >> 8));
                                        rlpNonce[4] = byte(uint8(nonce));
                                    }
                                }
                                /// @dev Compute the expected deployment address by `deployer` at
                                ///      the nonce given by `deploymentNonce`.
                                /// @param deployer The address of the deployer.
                                /// @param deploymentNonce The nonce that the deployer had when deploying
                                ///        a contract.
                                /// @return deploymentAddress The deployment address.
                                function getDeployedAddress(address deployer, uint32 deploymentNonce)
                                    internal
                                    pure
                                    returns (address payable deploymentAddress)
                                {
                                    // The address of if a deployed contract is the lower 20 bytes of the
                                    // hash of the RLP-encoded deployer's account address + account nonce.
                                    // See: https://ethereum.stackexchange.com/questions/760/how-is-the-address-of-an-ethereum-contract-computed
                                    bytes memory rlpNonce = rlpEncodeNonce(deploymentNonce);
                                    return address(uint160(uint256(keccak256(abi.encodePacked(
                                        byte(uint8(0xC0 + 21 + rlpNonce.length)),
                                        byte(uint8(0x80 + 20)),
                                        deployer,
                                        rlpNonce
                                    )))));
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../ZeroEx.sol";
                            import "../features/IOwnable.sol";
                            import "../features/TokenSpender.sol";
                            import "../features/TransformERC20.sol";
                            import "../features/SignatureValidator.sol";
                            import "../features/MetaTransactions.sol";
                            import "../external/AllowanceTarget.sol";
                            import "./InitialMigration.sol";
                            /// @dev A contract for deploying and configuring the full ZeroEx contract.
                            contract FullMigration {
                                // solhint-disable no-empty-blocks,indent
                                /// @dev Features to add the the proxy contract.
                                struct Features {
                                    SimpleFunctionRegistry registry;
                                    Ownable ownable;
                                    TokenSpender tokenSpender;
                                    TransformERC20 transformERC20;
                                    SignatureValidator signatureValidator;
                                    MetaTransactions metaTransactions;
                                }
                                /// @dev Parameters needed to initialize features.
                                struct MigrateOpts {
                                    address transformerDeployer;
                                }
                                /// @dev The allowed caller of `deploy()`.
                                address public immutable deployer;
                                /// @dev The initial migration contract.
                                InitialMigration private _initialMigration;
                                /// @dev Instantiate this contract and set the allowed caller of `deploy()`
                                ///      to `deployer`.
                                /// @param deployer_ The allowed caller of `deploy()`.
                                constructor(address payable deployer_)
                                    public
                                {
                                    deployer = deployer_;
                                    // Create an initial migration contract with this contract set to the
                                    // allowed deployer.
                                    _initialMigration = new InitialMigration(address(this));
                                }
                                /// @dev Retrieve the bootstrapper address to use when constructing `ZeroEx`.
                                /// @return bootstrapper The bootstrapper address.
                                function getBootstrapper()
                                    external
                                    view
                                    returns (address bootstrapper)
                                {
                                    return address(_initialMigration);
                                }
                                /// @dev Deploy the `ZeroEx` contract with the full feature set,
                                ///      transfer ownership to `owner`, then self-destruct.
                                /// @param owner The owner of the contract.
                                /// @param zeroEx The instance of the ZeroEx contract. ZeroEx should
                                ///        been constructed with this contract as the bootstrapper.
                                /// @param features Features to add to the proxy.
                                /// @return _zeroEx The configured ZeroEx contract. Same as the `zeroEx` parameter.
                                /// @param migrateOpts Parameters needed to initialize features.
                                function deploy(
                                    address payable owner,
                                    ZeroEx zeroEx,
                                    Features memory features,
                                    MigrateOpts memory migrateOpts
                                )
                                    public
                                    returns (ZeroEx _zeroEx)
                                {
                                    require(msg.sender == deployer, "FullMigration/INVALID_SENDER");
                                    // Perform the initial migration with the owner set to this contract.
                                    _initialMigration.deploy(
                                        address(uint160(address(this))),
                                        zeroEx,
                                        InitialMigration.BootstrapFeatures({
                                            registry: features.registry,
                                            ownable: features.ownable
                                        })
                                    );
                                    // Add features.
                                    _addFeatures(zeroEx, owner, features, migrateOpts);
                                    // Transfer ownership to the real owner.
                                    IOwnable(address(zeroEx)).transferOwnership(owner);
                                    // Self-destruct.
                                    this.die(owner);
                                    return zeroEx;
                                }
                                /// @dev Destroy this contract. Only callable from ourselves (from `deploy()`).
                                /// @param ethRecipient Receiver of any ETH in this contract.
                                function die(address payable ethRecipient)
                                    external
                                    virtual
                                {
                                    require(msg.sender == address(this), "FullMigration/INVALID_SENDER");
                                    // This contract should not hold any funds but we send
                                    // them to the ethRecipient just in case.
                                    selfdestruct(ethRecipient);
                                }
                                /// @dev Deploy and register features to the ZeroEx contract.
                                /// @param zeroEx The bootstrapped ZeroEx contract.
                                /// @param owner The ultimate owner of the ZeroEx contract.
                                /// @param features Features to add to the proxy.
                                /// @param migrateOpts Parameters needed to initialize features.
                                function _addFeatures(
                                    ZeroEx zeroEx,
                                    address owner,
                                    Features memory features,
                                    MigrateOpts memory migrateOpts
                                )
                                    private
                                {
                                    IOwnable ownable = IOwnable(address(zeroEx));
                                    // TokenSpender
                                    {
                                        // Create the allowance target.
                                        AllowanceTarget allowanceTarget = new AllowanceTarget();
                                        // Let the ZeroEx contract use the allowance target.
                                        allowanceTarget.addAuthorizedAddress(address(zeroEx));
                                        // Transfer ownership of the allowance target to the (real) owner.
                                        allowanceTarget.transferOwnership(owner);
                                        // Register the feature.
                                        ownable.migrate(
                                            address(features.tokenSpender),
                                            abi.encodeWithSelector(
                                                TokenSpender.migrate.selector,
                                                allowanceTarget
                                            ),
                                            address(this)
                                        );
                                    }
                                    // TransformERC20
                                    {
                                        // Register the feature.
                                        ownable.migrate(
                                            address(features.transformERC20),
                                            abi.encodeWithSelector(
                                                TransformERC20.migrate.selector,
                                                migrateOpts.transformerDeployer
                                            ),
                                            address(this)
                                        );
                                    }
                                    // SignatureValidator
                                    {
                                        // Register the feature.
                                        ownable.migrate(
                                            address(features.signatureValidator),
                                            abi.encodeWithSelector(
                                                SignatureValidator.migrate.selector
                                            ),
                                            address(this)
                                        );
                                    }
                                    // MetaTransactions
                                    {
                                        // Register the feature.
                                        ownable.migrate(
                                            address(features.metaTransactions),
                                            abi.encodeWithSelector(
                                                MetaTransactions.migrate.selector
                                            ),
                                            address(this)
                                        );
                                    }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../ZeroEx.sol";
                            import "../features/IBootstrap.sol";
                            import "../features/SimpleFunctionRegistry.sol";
                            import "../features/Ownable.sol";
                            import "./LibBootstrap.sol";
                            /// @dev A contract for deploying and configuring a minimal ZeroEx contract.
                            contract InitialMigration {
                                /// @dev Features to bootstrap into the the proxy contract.
                                struct BootstrapFeatures {
                                    SimpleFunctionRegistry registry;
                                    Ownable ownable;
                                }
                                /// @dev The allowed caller of `deploy()`. In production, this would be
                                ///      the governor.
                                address public immutable deployer;
                                /// @dev The real address of this contract.
                                address private immutable _implementation;
                                /// @dev Instantiate this contract and set the allowed caller of `deploy()`
                                ///      to `deployer_`.
                                /// @param deployer_ The allowed caller of `deploy()`.
                                constructor(address deployer_) public {
                                    deployer = deployer_;
                                    _implementation = address(this);
                                }
                                /// @dev Deploy the `ZeroEx` contract with the minimum feature set,
                                ///      transfers ownership to `owner`, then self-destructs.
                                ///      Only callable by `deployer` set in the contstructor.
                                /// @param owner The owner of the contract.
                                /// @param zeroEx The instance of the ZeroEx contract. ZeroEx should
                                ///        been constructed with this contract as the bootstrapper.
                                /// @param features Features to bootstrap into the proxy.
                                /// @return _zeroEx The configured ZeroEx contract. Same as the `zeroEx` parameter.
                                function deploy(
                                    address payable owner,
                                    ZeroEx zeroEx,
                                    BootstrapFeatures memory features
                                )
                                    public
                                    virtual
                                    returns (ZeroEx _zeroEx)
                                {
                                    // Must be called by the allowed deployer.
                                    require(msg.sender == deployer, "InitialMigration/INVALID_SENDER");
                                    // Bootstrap the initial feature set.
                                    IBootstrap(address(zeroEx)).bootstrap(
                                        address(this),
                                        abi.encodeWithSelector(this.bootstrap.selector, owner, features)
                                    );
                                    // Self-destruct. This contract should not hold any funds but we send
                                    // them to the owner just in case.
                                    this.die(owner);
                                    return zeroEx;
                                }
                                /// @dev Sets up the initial state of the `ZeroEx` contract.
                                ///      The `ZeroEx` contract will delegatecall into this function.
                                /// @param owner The new owner of the ZeroEx contract.
                                /// @param features Features to bootstrap into the proxy.
                                /// @return success Magic bytes if successful.
                                function bootstrap(address owner, BootstrapFeatures memory features)
                                    public
                                    virtual
                                    returns (bytes4 success)
                                {
                                    // Deploy and migrate the initial features.
                                    // Order matters here.
                                    // Initialize Registry.
                                    LibBootstrap.delegatecallBootstrapFunction(
                                        address(features.registry),
                                        abi.encodeWithSelector(
                                            SimpleFunctionRegistry.bootstrap.selector
                                        )
                                    );
                                    // Initialize Ownable.
                                    LibBootstrap.delegatecallBootstrapFunction(
                                        address(features.ownable),
                                        abi.encodeWithSelector(
                                            Ownable.bootstrap.selector
                                        )
                                    );
                                    // De-register `SimpleFunctionRegistry._extendSelf`.
                                    SimpleFunctionRegistry(address(this)).rollback(
                                        SimpleFunctionRegistry._extendSelf.selector,
                                        address(0)
                                    );
                                    // Transfer ownership to the real owner.
                                    Ownable(address(this)).transferOwnership(owner);
                                    success = LibBootstrap.BOOTSTRAP_SUCCESS;
                                }
                                /// @dev Self-destructs this contract. Only callable by this contract.
                                /// @param ethRecipient Who to transfer outstanding ETH to.
                                function die(address payable ethRecipient) public virtual {
                                    require(msg.sender == _implementation, "InitialMigration/INVALID_SENDER");
                                    selfdestruct(ethRecipient);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
                            import "../errors/LibTransformERC20RichErrors.sol";
                            import "./Transformer.sol";
                            import "./LibERC20Transformer.sol";
                            /// @dev A transformer that transfers tokens to arbitrary addresses.
                            contract AffiliateFeeTransformer is
                                Transformer
                            {
                                // solhint-disable no-empty-blocks
                                using LibRichErrorsV06 for bytes;
                                using LibSafeMathV06 for uint256;
                                using LibERC20Transformer for IERC20TokenV06;
                                /// @dev Information for a single fee.
                                struct TokenFee {
                                    // The token to transfer to `recipient`.
                                    IERC20TokenV06 token;
                                    // Amount of each `token` to transfer to `recipient`.
                                    // If `amount == uint256(-1)`, the entire balance of `token` will be
                                    // transferred.
                                    uint256 amount;
                                    // Recipient of `token`.
                                    address payable recipient;
                                }
                                uint256 private constant MAX_UINT256 = uint256(-1);
                                /// @dev Create this contract.
                                constructor()
                                    public
                                    Transformer()
                                {}
                                /// @dev Transfers tokens to recipients.
                                /// @param data ABI-encoded `TokenFee[]`, indicating which tokens to transfer.
                                /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
                                function transform(
                                    bytes32, // callDataHash,
                                    address payable, // taker,
                                    bytes calldata data
                                )
                                    external
                                    override
                                    returns (bytes4 success)
                                {
                                    TokenFee[] memory fees = abi.decode(data, (TokenFee[]));
                                    // Transfer tokens to recipients.
                                    for (uint256 i = 0; i < fees.length; ++i) {
                                        uint256 amount = fees[i].amount;
                                        if (amount == MAX_UINT256) {
                                            amount = LibERC20Transformer.getTokenBalanceOf(fees[i].token, address(this));
                                        }
                                        if (amount != 0) {
                                            fees[i].token.transformerTransfer(fees[i].recipient, amount);
                                        }
                                    }
                                    return LibERC20Transformer.TRANSFORMER_SUCCESS;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "../errors/LibTransformERC20RichErrors.sol";
                            import "./IERC20Transformer.sol";
                            /// @dev Abstract base class for transformers.
                            abstract contract Transformer is
                                IERC20Transformer
                            {
                                using LibRichErrorsV06 for bytes;
                                /// @dev The address of the deployer.
                                address public immutable deployer;
                                /// @dev The original address of this contract.
                                address private immutable _implementation;
                                /// @dev Create this contract.
                                constructor() public {
                                    deployer = msg.sender;
                                    _implementation = address(this);
                                }
                                /// @dev Destruct this contract. Only callable by the deployer and will not
                                ///      succeed in the context of a delegatecall (from another contract).
                                /// @param ethRecipient The recipient of ETH held in this contract.
                                function die(address payable ethRecipient)
                                    external
                                    virtual
                                {
                                    // Only the deployer can call this.
                                    if (msg.sender != deployer) {
                                        LibTransformERC20RichErrors
                                            .OnlyCallableByDeployerError(msg.sender, deployer)
                                            .rrevert();
                                    }
                                    // Must be executing our own context.
                                    if (address(this) != _implementation) {
                                        LibTransformERC20RichErrors
                                            .InvalidExecutionContextError(address(this), _implementation)
                                            .rrevert();
                                    }
                                    selfdestruct(ethRecipient);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibMathV06.sol";
                            import "../errors/LibTransformERC20RichErrors.sol";
                            import "../vendor/v3/IExchange.sol";
                            import "./Transformer.sol";
                            import "./LibERC20Transformer.sol";
                            /// @dev A transformer that fills an ERC20 market sell/buy quote.
                            contract FillQuoteTransformer is
                                Transformer
                            {
                                using LibERC20TokenV06 for IERC20TokenV06;
                                using LibERC20Transformer for IERC20TokenV06;
                                using LibSafeMathV06 for uint256;
                                using LibRichErrorsV06 for bytes;
                                /// @dev Whether we are performing a market sell or buy.
                                enum Side {
                                    Sell,
                                    Buy
                                }
                                /// @dev Transform data to ABI-encode and pass into `transform()`.
                                struct TransformData {
                                    // Whether we aer performing a market sell or buy.
                                    Side side;
                                    // The token being sold.
                                    // This should be an actual token, not the ETH pseudo-token.
                                    IERC20TokenV06 sellToken;
                                    // The token being bought.
                                    // This should be an actual token, not the ETH pseudo-token.
                                    IERC20TokenV06 buyToken;
                                    // The orders to fill.
                                    IExchange.Order[] orders;
                                    // Signatures for each respective order in `orders`.
                                    bytes[] signatures;
                                    // Maximum fill amount for each order. This may be shorter than the
                                    // number of orders, where missing entries will be treated as `uint256(-1)`.
                                    // For sells, this will be the maximum sell amount (taker asset).
                                    // For buys, this will be the maximum buy amount (maker asset).
                                    uint256[] maxOrderFillAmounts;
                                    // Amount of `sellToken` to sell or `buyToken` to buy.
                                    // For sells, this may be `uint256(-1)` to sell the entire balance of
                                    // `sellToken`.
                                    uint256 fillAmount;
                                }
                                /// @dev Results of a call to `_fillOrder()`.
                                struct FillOrderResults {
                                    // The amount of taker tokens sold, according to balance checks.
                                    uint256 takerTokenSoldAmount;
                                    // The amount of maker tokens sold, according to balance checks.
                                    uint256 makerTokenBoughtAmount;
                                    // The amount of protocol fee paid.
                                    uint256 protocolFeePaid;
                                }
                                /// @dev The Exchange ERC20Proxy ID.
                                bytes4 private constant ERC20_ASSET_PROXY_ID = 0xf47261b0;
                                /// @dev Maximum uint256 value.
                                uint256 private constant MAX_UINT256 = uint256(-1);
                                /// @dev The Exchange contract.
                                IExchange public immutable exchange;
                                /// @dev The ERC20Proxy address.
                                address public immutable erc20Proxy;
                                /// @dev Create this contract.
                                /// @param exchange_ The Exchange V3 instance.
                                constructor(IExchange exchange_)
                                    public
                                    Transformer()
                                {
                                    exchange = exchange_;
                                    erc20Proxy = exchange_.getAssetProxy(ERC20_ASSET_PROXY_ID);
                                }
                                /// @dev Sell this contract's entire balance of of `sellToken` in exchange
                                ///      for `buyToken` by filling `orders`. Protocol fees should be attached
                                ///      to this call. `buyToken` and excess ETH will be transferred back to the caller.
                                /// @param data_ ABI-encoded `TransformData`.
                                /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
                                function transform(
                                    bytes32, // callDataHash,
                                    address payable, // taker,
                                    bytes calldata data_
                                )
                                    external
                                    override
                                    returns (bytes4 success)
                                {
                                    TransformData memory data = abi.decode(data_, (TransformData));
                                    // Validate data fields.
                                    if (data.sellToken.isTokenETH() || data.buyToken.isTokenETH()) {
                                        LibTransformERC20RichErrors.InvalidTransformDataError(
                                            LibTransformERC20RichErrors.InvalidTransformDataErrorCode.INVALID_TOKENS,
                                            data_
                                        ).rrevert();
                                    }
                                    if (data.orders.length != data.signatures.length) {
                                        LibTransformERC20RichErrors.InvalidTransformDataError(
                                            LibTransformERC20RichErrors.InvalidTransformDataErrorCode.INVALID_ARRAY_LENGTH,
                                            data_
                                        ).rrevert();
                                    }
                                    if (data.side == Side.Sell && data.fillAmount == MAX_UINT256) {
                                        // If `sellAmount == -1 then we are selling
                                        // the entire balance of `sellToken`. This is useful in cases where
                                        // the exact sell amount is not exactly known in advance, like when
                                        // unwrapping Chai/cUSDC/cDAI.
                                        data.fillAmount = data.sellToken.getTokenBalanceOf(address(this));
                                    }
                                    // Approve the ERC20 proxy to spend `sellToken`.
                                    data.sellToken.approveIfBelow(erc20Proxy, data.fillAmount);
                                    // Fill the orders.
                                    uint256 singleProtocolFee = exchange.protocolFeeMultiplier().safeMul(tx.gasprice);
                                    uint256 ethRemaining = address(this).balance;
                                    uint256 boughtAmount = 0;
                                    uint256 soldAmount = 0;
                                    for (uint256 i = 0; i < data.orders.length; ++i) {
                                        // Check if we've hit our targets.
                                        if (data.side == Side.Sell) {
                                            // Market sell check.
                                            if (soldAmount >= data.fillAmount) {
                                                break;
                                            }
                                        } else {
                                            // Market buy check.
                                            if (boughtAmount >= data.fillAmount) {
                                                break;
                                            }
                                        }
                                        // Ensure we have enough ETH to cover the protocol fee.
                                        if (ethRemaining < singleProtocolFee) {
                                            LibTransformERC20RichErrors
                                                .InsufficientProtocolFeeError(ethRemaining, singleProtocolFee)
                                                .rrevert();
                                        }
                                        // Fill the order.
                                        FillOrderResults memory results;
                                        if (data.side == Side.Sell) {
                                            // Market sell.
                                            results = _sellToOrder(
                                                data.buyToken,
                                                data.sellToken,
                                                data.orders[i],
                                                data.signatures[i],
                                                data.fillAmount.safeSub(soldAmount).min256(
                                                    data.maxOrderFillAmounts.length > i
                                                    ? data.maxOrderFillAmounts[i]
                                                    : MAX_UINT256
                                                ),
                                                singleProtocolFee
                                            );
                                        } else {
                                            // Market buy.
                                            results = _buyFromOrder(
                                                data.buyToken,
                                                data.sellToken,
                                                data.orders[i],
                                                data.signatures[i],
                                                data.fillAmount.safeSub(boughtAmount).min256(
                                                    data.maxOrderFillAmounts.length > i
                                                    ? data.maxOrderFillAmounts[i]
                                                    : MAX_UINT256
                                                ),
                                                singleProtocolFee
                                            );
                                        }
                                        // Accumulate totals.
                                        soldAmount = soldAmount.safeAdd(results.takerTokenSoldAmount);
                                        boughtAmount = boughtAmount.safeAdd(results.makerTokenBoughtAmount);
                                        ethRemaining = ethRemaining.safeSub(results.protocolFeePaid);
                                    }
                                    // Ensure we hit our targets.
                                    if (data.side == Side.Sell) {
                                        // Market sell check.
                                        if (soldAmount < data.fillAmount) {
                                            LibTransformERC20RichErrors
                                                .IncompleteFillSellQuoteError(
                                                    address(data.sellToken),
                                                    soldAmount,
                                                    data.fillAmount
                                                ).rrevert();
                                        }
                                    } else {
                                        // Market buy check.
                                        if (boughtAmount < data.fillAmount) {
                                            LibTransformERC20RichErrors
                                                .IncompleteFillBuyQuoteError(
                                                    address(data.buyToken),
                                                    boughtAmount,
                                                    data.fillAmount
                                                ).rrevert();
                                        }
                                    }
                                    return LibERC20Transformer.TRANSFORMER_SUCCESS;
                                }
                                /// @dev Try to sell up to `sellAmount` from an order.
                                /// @param makerToken The maker/buy token.
                                /// @param takerToken The taker/sell token.
                                /// @param order The order to fill.
                                /// @param signature The signature for `order`.
                                /// @param sellAmount Amount of taker token to sell.
                                /// @param protocolFee The protocol fee needed to fill `order`.
                                function _sellToOrder(
                                    IERC20TokenV06 makerToken,
                                    IERC20TokenV06 takerToken,
                                    IExchange.Order memory order,
                                    bytes memory signature,
                                    uint256 sellAmount,
                                    uint256 protocolFee
                                )
                                    private
                                    returns (FillOrderResults memory results)
                                {
                                    IERC20TokenV06 takerFeeToken =
                                        _getTokenFromERC20AssetData(order.takerFeeAssetData);
                                    uint256 takerTokenFillAmount = sellAmount;
                                    if (order.takerFee != 0) {
                                        if (takerFeeToken == makerToken) {
                                            // Taker fee is payable in the maker token, so we need to
                                            // approve the proxy to spend the maker token.
                                            // It isn't worth computing the actual taker fee
                                            // since `approveIfBelow()` will set the allowance to infinite. We
                                            // just need a reasonable upper bound to avoid unnecessarily re-approving.
                                            takerFeeToken.approveIfBelow(erc20Proxy, order.takerFee);
                                        } else if (takerFeeToken == takerToken){
                                            // Taker fee is payable in the taker token, so we need to
                                            // reduce the fill amount to cover the fee.
                                            // takerTokenFillAmount' =
                                            //   (takerTokenFillAmount * order.takerAssetAmount) /
                                            //   (order.takerAssetAmount + order.takerFee)
                                            takerTokenFillAmount = LibMathV06.getPartialAmountCeil(
                                                order.takerAssetAmount,
                                                order.takerAssetAmount.safeAdd(order.takerFee),
                                                sellAmount
                                            );
                                        } else {
                                            //  Only support taker or maker asset denominated taker fees.
                                            LibTransformERC20RichErrors.InvalidTakerFeeTokenError(
                                                address(takerFeeToken)
                                            ).rrevert();
                                        }
                                    }
                                    // Clamp fill amount to order size.
                                    takerTokenFillAmount = LibSafeMathV06.min256(
                                        takerTokenFillAmount,
                                        order.takerAssetAmount
                                    );
                                    // Perform the fill.
                                    return _fillOrder(
                                        order,
                                        signature,
                                        takerTokenFillAmount,
                                        protocolFee,
                                        makerToken,
                                        takerFeeToken == takerToken
                                    );
                                }
                                /// @dev Try to buy up to `buyAmount` from an order.
                                /// @param makerToken The maker/buy token.
                                /// @param takerToken The taker/sell token.
                                /// @param order The order to fill.
                                /// @param signature The signature for `order`.
                                /// @param buyAmount Amount of maker token to buy.
                                /// @param protocolFee The protocol fee needed to fill `order`.
                                function _buyFromOrder(
                                    IERC20TokenV06 makerToken,
                                    IERC20TokenV06 takerToken,
                                    IExchange.Order memory order,
                                    bytes memory signature,
                                    uint256 buyAmount,
                                    uint256 protocolFee
                                )
                                    private
                                    returns (FillOrderResults memory results)
                                {
                                    IERC20TokenV06 takerFeeToken =
                                        _getTokenFromERC20AssetData(order.takerFeeAssetData);
                                    // Compute the default taker token fill amount.
                                    uint256 takerTokenFillAmount = LibMathV06.getPartialAmountCeil(
                                        buyAmount,
                                        order.makerAssetAmount,
                                        order.takerAssetAmount
                                    );
                                    if (order.takerFee != 0) {
                                        if (takerFeeToken == makerToken) {
                                            // Taker fee is payable in the maker token.
                                            // Adjust the taker token fill amount to account for maker
                                            // tokens being lost to the taker fee.
                                            // takerTokenFillAmount' =
                                            //  (order.takerAssetAmount * buyAmount) /
                                            //  (order.makerAssetAmount - order.takerFee)
                                            takerTokenFillAmount = LibMathV06.getPartialAmountCeil(
                                                buyAmount,
                                                order.makerAssetAmount.safeSub(order.takerFee),
                                                order.takerAssetAmount
                                            );
                                            // Approve the proxy to spend the maker token.
                                            // It isn't worth computing the actual taker fee
                                            // since `approveIfBelow()` will set the allowance to infinite. We
                                            // just need a reasonable upper bound to avoid unnecessarily re-approving.
                                            takerFeeToken.approveIfBelow(erc20Proxy, order.takerFee);
                                        } else if (takerFeeToken != takerToken) {
                                            //  Only support taker or maker asset denominated taker fees.
                                            LibTransformERC20RichErrors.InvalidTakerFeeTokenError(
                                                address(takerFeeToken)
                                            ).rrevert();
                                        }
                                    }
                                    // Clamp to order size.
                                    takerTokenFillAmount = LibSafeMathV06.min256(
                                        order.takerAssetAmount,
                                        takerTokenFillAmount
                                    );
                                    // Perform the fill.
                                    return _fillOrder(
                                        order,
                                        signature,
                                        takerTokenFillAmount,
                                        protocolFee,
                                        makerToken,
                                        takerFeeToken == takerToken
                                    );
                                }
                                /// @dev Attempt to fill an order. If the fill reverts, the revert will be
                                ///      swallowed and `results` will be zeroed out.
                                /// @param order The order to fill.
                                /// @param signature The order signature.
                                /// @param takerAssetFillAmount How much taker asset to fill.
                                /// @param protocolFee The protocol fee needed to fill this order.
                                /// @param makerToken The maker token.
                                /// @param isTakerFeeInTakerToken Whether the taker fee token is the same as the
                                ///        taker token.
                                function _fillOrder(
                                    IExchange.Order memory order,
                                    bytes memory signature,
                                    uint256 takerAssetFillAmount,
                                    uint256 protocolFee,
                                    IERC20TokenV06 makerToken,
                                    bool isTakerFeeInTakerToken
                                )
                                    private
                                    returns (FillOrderResults memory results)
                                {
                                    // Track changes in the maker token balance.
                                    uint256 initialMakerTokenBalance = makerToken.balanceOf(address(this));
                                    try
                                        exchange.fillOrder
                                            {value: protocolFee}
                                            (order, takerAssetFillAmount, signature)
                                        returns (IExchange.FillResults memory fillResults)
                                    {
                                        // Update maker quantity based on changes in token balances.
                                        results.makerTokenBoughtAmount = makerToken.balanceOf(address(this))
                                            .safeSub(initialMakerTokenBalance);
                                        // We can trust the other fill result quantities.
                                        results.protocolFeePaid = fillResults.protocolFeePaid;
                                        results.takerTokenSoldAmount = fillResults.takerAssetFilledAmount;
                                        // If the taker fee is payable in the taker asset, include the
                                        // taker fee in the total amount sold.
                                        if (isTakerFeeInTakerToken) {
                                            results.takerTokenSoldAmount =
                                                results.takerTokenSoldAmount.safeAdd(fillResults.takerFeePaid);
                                        }
                                    } catch (bytes memory) {
                                        // Swallow failures, leaving all results as zero.
                                    }
                                }
                                /// @dev Extract the token from plain ERC20 asset data.
                                ///      If the asset-data is empty, a zero token address will be returned.
                                /// @param assetData The order asset data.
                                function _getTokenFromERC20AssetData(bytes memory assetData)
                                    private
                                    pure
                                    returns (IERC20TokenV06 token)
                                {
                                    if (assetData.length == 0) {
                                        return IERC20TokenV06(address(0));
                                    }
                                    if (assetData.length != 36 ||
                                        LibBytesV06.readBytes4(assetData, 0) != ERC20_ASSET_PROXY_ID)
                                    {
                                        LibTransformERC20RichErrors
                                            .InvalidERC20AssetDataError(assetData)
                                            .rrevert();
                                    }
                                    return IERC20TokenV06(LibBytesV06.readAddress(assetData, 16));
                                }
                            }
                            /*
                              Copyright 2019 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./LibSafeMathV06.sol";
                            import "./errors/LibRichErrorsV06.sol";
                            import "./errors/LibMathRichErrorsV06.sol";
                            library LibMathV06 {
                                using LibSafeMathV06 for uint256;
                                /// @dev Calculates partial value given a numerator and denominator rounded down.
                                ///      Reverts if rounding error is >= 0.1%
                                /// @param numerator Numerator.
                                /// @param denominator Denominator.
                                /// @param target Value to calculate partial of.
                                /// @return partialAmount Partial value of target rounded down.
                                function safeGetPartialAmountFloor(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                )
                                    internal
                                    pure
                                    returns (uint256 partialAmount)
                                {
                                    if (isRoundingErrorFloor(
                                            numerator,
                                            denominator,
                                            target
                                    )) {
                                        LibRichErrorsV06.rrevert(LibMathRichErrorsV06.RoundingError(
                                            numerator,
                                            denominator,
                                            target
                                        ));
                                    }
                                    partialAmount = numerator.safeMul(target).safeDiv(denominator);
                                    return partialAmount;
                                }
                                /// @dev Calculates partial value given a numerator and denominator rounded down.
                                ///      Reverts if rounding error is >= 0.1%
                                /// @param numerator Numerator.
                                /// @param denominator Denominator.
                                /// @param target Value to calculate partial of.
                                /// @return partialAmount Partial value of target rounded up.
                                function safeGetPartialAmountCeil(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                )
                                    internal
                                    pure
                                    returns (uint256 partialAmount)
                                {
                                    if (isRoundingErrorCeil(
                                            numerator,
                                            denominator,
                                            target
                                    )) {
                                        LibRichErrorsV06.rrevert(LibMathRichErrorsV06.RoundingError(
                                            numerator,
                                            denominator,
                                            target
                                        ));
                                    }
                                    // safeDiv computes `floor(a / b)`. We use the identity (a, b integer):
                                    //       ceil(a / b) = floor((a + b - 1) / b)
                                    // To implement `ceil(a / b)` using safeDiv.
                                    partialAmount = numerator.safeMul(target)
                                        .safeAdd(denominator.safeSub(1))
                                        .safeDiv(denominator);
                                    return partialAmount;
                                }
                                /// @dev Calculates partial value given a numerator and denominator rounded down.
                                /// @param numerator Numerator.
                                /// @param denominator Denominator.
                                /// @param target Value to calculate partial of.
                                /// @return partialAmount Partial value of target rounded down.
                                function getPartialAmountFloor(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                )
                                    internal
                                    pure
                                    returns (uint256 partialAmount)
                                {
                                    partialAmount = numerator.safeMul(target).safeDiv(denominator);
                                    return partialAmount;
                                }
                                /// @dev Calculates partial value given a numerator and denominator rounded down.
                                /// @param numerator Numerator.
                                /// @param denominator Denominator.
                                /// @param target Value to calculate partial of.
                                /// @return partialAmount Partial value of target rounded up.
                                function getPartialAmountCeil(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                )
                                    internal
                                    pure
                                    returns (uint256 partialAmount)
                                {
                                    // safeDiv computes `floor(a / b)`. We use the identity (a, b integer):
                                    //       ceil(a / b) = floor((a + b - 1) / b)
                                    // To implement `ceil(a / b)` using safeDiv.
                                    partialAmount = numerator.safeMul(target)
                                        .safeAdd(denominator.safeSub(1))
                                        .safeDiv(denominator);
                                    return partialAmount;
                                }
                                /// @dev Checks if rounding error >= 0.1% when rounding down.
                                /// @param numerator Numerator.
                                /// @param denominator Denominator.
                                /// @param target Value to multiply with numerator/denominator.
                                /// @return isError Rounding error is present.
                                function isRoundingErrorFloor(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                )
                                    internal
                                    pure
                                    returns (bool isError)
                                {
                                    if (denominator == 0) {
                                        LibRichErrorsV06.rrevert(LibMathRichErrorsV06.DivisionByZeroError());
                                    }
                                    // The absolute rounding error is the difference between the rounded
                                    // value and the ideal value. The relative rounding error is the
                                    // absolute rounding error divided by the absolute value of the
                                    // ideal value. This is undefined when the ideal value is zero.
                                    //
                                    // The ideal value is `numerator * target / denominator`.
                                    // Let's call `numerator * target % denominator` the remainder.
                                    // The absolute error is `remainder / denominator`.
                                    //
                                    // When the ideal value is zero, we require the absolute error to
                                    // be zero. Fortunately, this is always the case. The ideal value is
                                    // zero iff `numerator == 0` and/or `target == 0`. In this case the
                                    // remainder and absolute error are also zero.
                                    if (target == 0 || numerator == 0) {
                                        return false;
                                    }
                                    // Otherwise, we want the relative rounding error to be strictly
                                    // less than 0.1%.
                                    // The relative error is `remainder / (numerator * target)`.
                                    // We want the relative error less than 1 / 1000:
                                    //        remainder / (numerator * denominator)  <  1 / 1000
                                    // or equivalently:
                                    //        1000 * remainder  <  numerator * target
                                    // so we have a rounding error iff:
                                    //        1000 * remainder  >=  numerator * target
                                    uint256 remainder = mulmod(
                                        target,
                                        numerator,
                                        denominator
                                    );
                                    isError = remainder.safeMul(1000) >= numerator.safeMul(target);
                                    return isError;
                                }
                                /// @dev Checks if rounding error >= 0.1% when rounding up.
                                /// @param numerator Numerator.
                                /// @param denominator Denominator.
                                /// @param target Value to multiply with numerator/denominator.
                                /// @return isError Rounding error is present.
                                function isRoundingErrorCeil(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                )
                                    internal
                                    pure
                                    returns (bool isError)
                                {
                                    if (denominator == 0) {
                                        LibRichErrorsV06.rrevert(LibMathRichErrorsV06.DivisionByZeroError());
                                    }
                                    // See the comments in `isRoundingError`.
                                    if (target == 0 || numerator == 0) {
                                        // When either is zero, the ideal value and rounded value are zero
                                        // and there is no rounding error. (Although the relative error
                                        // is undefined.)
                                        return false;
                                    }
                                    // Compute remainder as before
                                    uint256 remainder = mulmod(
                                        target,
                                        numerator,
                                        denominator
                                    );
                                    remainder = denominator.safeSub(remainder) % denominator;
                                    isError = remainder.safeMul(1000) >= numerator.safeMul(target);
                                    return isError;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibMathRichErrorsV06 {
                                // bytes4(keccak256("DivisionByZeroError()"))
                                bytes internal constant DIVISION_BY_ZERO_ERROR =
                                    hex"a791837c";
                                // bytes4(keccak256("RoundingError(uint256,uint256,uint256)"))
                                bytes4 internal constant ROUNDING_ERROR_SELECTOR =
                                    0x339f3de2;
                                // solhint-disable func-name-mixedcase
                                function DivisionByZeroError()
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return DIVISION_BY_ZERO_ERROR;
                                }
                                function RoundingError(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                )
                                    internal
                                    pure
                                    returns (bytes memory)
                                {
                                    return abi.encodeWithSelector(
                                        ROUNDING_ERROR_SELECTOR,
                                        numerator,
                                        denominator,
                                        target
                                    );
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            /// @dev Interface to the V3 Exchange.
                            interface IExchange {
                                /// @dev V3 Order structure.
                                struct Order {
                                    // Address that created the order.
                                    address makerAddress;
                                    // Address that is allowed to fill the order.
                                    // If set to 0, any address is allowed to fill the order.
                                    address takerAddress;
                                    // Address that will recieve fees when order is filled.
                                    address feeRecipientAddress;
                                    // Address that is allowed to call Exchange contract methods that affect this order.
                                    // If set to 0, any address is allowed to call these methods.
                                    address senderAddress;
                                    // Amount of makerAsset being offered by maker. Must be greater than 0.
                                    uint256 makerAssetAmount;
                                    // Amount of takerAsset being bid on by maker. Must be greater than 0.
                                    uint256 takerAssetAmount;
                                    // Fee paid to feeRecipient by maker when order is filled.
                                    uint256 makerFee;
                                    // Fee paid to feeRecipient by taker when order is filled.
                                    uint256 takerFee;
                                    // Timestamp in seconds at which order expires.
                                    uint256 expirationTimeSeconds;
                                    // Arbitrary number to facilitate uniqueness of the order's hash.
                                    uint256 salt;
                                    // Encoded data that can be decoded by a specified proxy contract when transferring makerAsset.
                                    // The leading bytes4 references the id of the asset proxy.
                                    bytes makerAssetData;
                                    // Encoded data that can be decoded by a specified proxy contract when transferring takerAsset.
                                    // The leading bytes4 references the id of the asset proxy.
                                    bytes takerAssetData;
                                    // Encoded data that can be decoded by a specified proxy contract when transferring makerFeeAsset.
                                    // The leading bytes4 references the id of the asset proxy.
                                    bytes makerFeeAssetData;
                                    // Encoded data that can be decoded by a specified proxy contract when transferring takerFeeAsset.
                                    // The leading bytes4 references the id of the asset proxy.
                                    bytes takerFeeAssetData;
                                }
                                /// @dev V3 `fillOrder()` results.`
                                struct FillResults {
                                    // Total amount of makerAsset(s) filled.
                                    uint256 makerAssetFilledAmount;
                                    // Total amount of takerAsset(s) filled.
                                    uint256 takerAssetFilledAmount;
                                    // Total amount of fees paid by maker(s) to feeRecipient(s).
                                    uint256 makerFeePaid;
                                    // Total amount of fees paid by taker to feeRecipients(s).
                                    uint256 takerFeePaid;
                                    // Total amount of fees paid by taker to the staking contract.
                                    uint256 protocolFeePaid;
                                }
                                /// @dev Fills the input order.
                                /// @param order Order struct containing order specifications.
                                /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
                                /// @param signature Proof that order has been created by maker.
                                /// @return fillResults Amounts filled and fees paid by maker and taker.
                                function fillOrder(
                                    Order calldata order,
                                    uint256 takerAssetFillAmount,
                                    bytes calldata signature
                                )
                                    external
                                    payable
                                    returns (FillResults memory fillResults);
                                /// @dev Returns the protocolFeeMultiplier
                                /// @return multiplier The multiplier for protocol fees.
                                function protocolFeeMultiplier()
                                    external
                                    view
                                    returns (uint256 multiplier);
                                /// @dev Gets an asset proxy.
                                /// @param assetProxyId Id of the asset proxy.
                                /// @return proxyAddress The asset proxy registered to assetProxyId.
                                ///         Returns 0x0 if no proxy is registered.
                                function getAssetProxy(bytes4 assetProxyId)
                                    external
                                    view
                                    returns (address proxyAddress);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/LibERC20TokenV06.sol";
                            import "../errors/LibTransformERC20RichErrors.sol";
                            import "./Transformer.sol";
                            import "./LibERC20Transformer.sol";
                            /// @dev A transformer that transfers tokens to the taker.
                            contract PayTakerTransformer is
                                Transformer
                            {
                                // solhint-disable no-empty-blocks
                                using LibRichErrorsV06 for bytes;
                                using LibSafeMathV06 for uint256;
                                using LibERC20Transformer for IERC20TokenV06;
                                /// @dev Transform data to ABI-encode and pass into `transform()`.
                                struct TransformData {
                                    // The tokens to transfer to the taker.
                                    IERC20TokenV06[] tokens;
                                    // Amount of each token in `tokens` to transfer to the taker.
                                    // `uint(-1)` will transfer the entire balance.
                                    uint256[] amounts;
                                }
                                /// @dev Maximum uint256 value.
                                uint256 private constant MAX_UINT256 = uint256(-1);
                                /// @dev Create this contract.
                                constructor()
                                    public
                                    Transformer()
                                {}
                                /// @dev Forwards tokens to the taker.
                                /// @param taker The taker address (caller of `TransformERC20.transformERC20()`).
                                /// @param data_ ABI-encoded `TransformData`, indicating which tokens to transfer.
                                /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
                                function transform(
                                    bytes32, // callDataHash,
                                    address payable taker,
                                    bytes calldata data_
                                )
                                    external
                                    override
                                    returns (bytes4 success)
                                {
                                    TransformData memory data = abi.decode(data_, (TransformData));
                                    // Transfer tokens directly to the taker.
                                    for (uint256 i = 0; i < data.tokens.length; ++i) {
                                        // The `amounts` array can be shorter than the `tokens` array.
                                        // Missing elements are treated as `uint256(-1)`.
                                        uint256 amount = data.amounts.length > i ? data.amounts[i] : uint256(-1);
                                        if (amount == MAX_UINT256) {
                                            amount = data.tokens[i].getTokenBalanceOf(address(this));
                                        }
                                        if (amount != 0) {
                                            data.tokens[i].transformerTransfer(taker, amount);
                                        }
                                    }
                                    return LibERC20Transformer.TRANSFORMER_SUCCESS;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/IEtherTokenV06.sol";
                            import "../errors/LibTransformERC20RichErrors.sol";
                            import "./Transformer.sol";
                            import "./LibERC20Transformer.sol";
                            /// @dev A transformer that wraps or unwraps WETH.
                            contract WethTransformer is
                                Transformer
                            {
                                using LibRichErrorsV06 for bytes;
                                using LibSafeMathV06 for uint256;
                                using LibERC20Transformer for IERC20TokenV06;
                                /// @dev Transform data to ABI-encode and pass into `transform()`.
                                struct TransformData {
                                    // The token to wrap/unwrap. Must be either ETH or WETH.
                                    IERC20TokenV06 token;
                                    // Amount of `token` to wrap or unwrap.
                                    // `uint(-1)` will unwrap the entire balance.
                                    uint256 amount;
                                }
                                /// @dev The WETH contract address.
                                IEtherTokenV06 public immutable weth;
                                /// @dev Maximum uint256 value.
                                uint256 private constant MAX_UINT256 = uint256(-1);
                                /// @dev Construct the transformer and store the WETH address in an immutable.
                                /// @param weth_ The weth token.
                                constructor(IEtherTokenV06 weth_)
                                    public
                                    Transformer()
                                {
                                    weth = weth_;
                                }
                                /// @dev Wraps and unwraps WETH.
                                /// @param data_ ABI-encoded `TransformData`, indicating which token to wrap/umwrap.
                                /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
                                function transform(
                                    bytes32, // callDataHash,
                                    address payable, // taker,
                                    bytes calldata data_
                                )
                                    external
                                    override
                                    returns (bytes4 success)
                                {
                                    TransformData memory data = abi.decode(data_, (TransformData));
                                    if (!data.token.isTokenETH() && data.token != weth) {
                                        LibTransformERC20RichErrors.InvalidTransformDataError(
                                            LibTransformERC20RichErrors.InvalidTransformDataErrorCode.INVALID_TOKENS,
                                            data_
                                        ).rrevert();
                                    }
                                    uint256 amount = data.amount;
                                    if (amount == MAX_UINT256) {
                                        amount = data.token.getTokenBalanceOf(address(this));
                                    }
                                    if (amount != 0) {
                                        if (data.token.isTokenETH()) {
                                            // Wrap ETH.
                                            weth.deposit{value: amount}();
                                        } else {
                                            // Unwrap WETH.
                                            weth.withdraw(amount);
                                        }
                                    }
                                    return LibERC20Transformer.TRANSFORMER_SUCCESS;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./IERC20TokenV06.sol";
                            interface IEtherTokenV06 is
                                IERC20TokenV06
                            {
                                /// @dev Wrap ether.
                                function deposit() external payable;
                                /// @dev Unwrap ether.
                                function withdraw(uint256 amount) external;
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            interface ITestSimpleFunctionRegistryFeature {
                                function testFn() external view returns (uint256 id);
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            contract TestCallTarget {
                                event CallTargetCalled(
                                    address context,
                                    address sender,
                                    bytes data,
                                    uint256 value
                                );
                                bytes4 private constant MAGIC_BYTES = 0x12345678;
                                bytes private constant REVERTING_DATA = hex"1337";
                                fallback() external payable {
                                    if (keccak256(msg.data) == keccak256(REVERTING_DATA)) {
                                        revert("TestCallTarget/REVERT");
                                    }
                                    emit CallTargetCalled(
                                        address(this),
                                        msg.sender,
                                        msg.data,
                                        msg.value
                                    );
                                    bytes4 rval = MAGIC_BYTES;
                                    assembly {
                                        mstore(0, rval)
                                        return(0, 32)
                                    }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            contract TestDelegateCaller {
                                function executeDelegateCall(
                                    address target,
                                    bytes calldata callData
                                )
                                    external
                                {
                                    (bool success, bytes memory resultData) = target.delegatecall(callData);
                                    if (!success) {
                                        assembly { revert(add(resultData, 32), mload(resultData)) }
                                    }
                                    assembly { return(add(resultData, 32), mload(resultData)) }
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibMathV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            import "../src/vendor/v3/IExchange.sol";
                            import "./TestMintableERC20Token.sol";
                            contract TestFillQuoteTransformerExchange {
                                struct FillBehavior {
                                    // How much of the order is filled, in taker asset amount.
                                    uint256 filledTakerAssetAmount;
                                    // Scaling for maker assets minted, in 1e18.
                                    uint256 makerAssetMintRatio;
                                }
                                uint256 private constant PROTOCOL_FEE_MULTIPLIER = 1337;
                                using LibSafeMathV06 for uint256;
                                function fillOrder(
                                    IExchange.Order calldata order,
                                    uint256 takerAssetFillAmount,
                                    bytes calldata signature
                                )
                                    external
                                    payable
                                    returns (IExchange.FillResults memory fillResults)
                                {
                                    require(
                                        signature.length != 0,
                                        "TestFillQuoteTransformerExchange/INVALID_SIGNATURE"
                                    );
                                    // The signature is the ABI-encoded FillBehavior data.
                                    FillBehavior memory behavior = abi.decode(signature, (FillBehavior));
                                    uint256 protocolFee = PROTOCOL_FEE_MULTIPLIER * tx.gasprice;
                                    require(
                                        msg.value == protocolFee,
                                        "TestFillQuoteTransformerExchange/INSUFFICIENT_PROTOCOL_FEE"
                                    );
                                    // Return excess protocol fee.
                                    msg.sender.transfer(msg.value - protocolFee);
                                    // Take taker tokens.
                                    TestMintableERC20Token takerToken = _getTokenFromAssetData(order.takerAssetData);
                                    takerAssetFillAmount = LibSafeMathV06.min256(
                                        order.takerAssetAmount.safeSub(behavior.filledTakerAssetAmount),
                                        takerAssetFillAmount
                                    );
                                    require(
                                        takerToken.getSpendableAmount(msg.sender, address(this)) >= takerAssetFillAmount,
                                        "TestFillQuoteTransformerExchange/INSUFFICIENT_TAKER_FUNDS"
                                    );
                                    takerToken.transferFrom(msg.sender, order.makerAddress, takerAssetFillAmount);
                                    // Mint maker tokens.
                                    uint256 makerAssetFilledAmount = LibMathV06.getPartialAmountFloor(
                                        takerAssetFillAmount,
                                        order.takerAssetAmount,
                                        order.makerAssetAmount
                                    );
                                    TestMintableERC20Token makerToken = _getTokenFromAssetData(order.makerAssetData);
                                    makerToken.mint(
                                        msg.sender,
                                        LibMathV06.getPartialAmountFloor(
                                            behavior.makerAssetMintRatio,
                                            1e18,
                                            makerAssetFilledAmount
                                        )
                                    );
                                    // Take taker fee.
                                    TestMintableERC20Token takerFeeToken = _getTokenFromAssetData(order.takerFeeAssetData);
                                    uint256 takerFee = LibMathV06.getPartialAmountFloor(
                                        takerAssetFillAmount,
                                        order.takerAssetAmount,
                                        order.takerFee
                                    );
                                    require(
                                        takerFeeToken.getSpendableAmount(msg.sender, address(this)) >= takerFee,
                                        "TestFillQuoteTransformerExchange/INSUFFICIENT_TAKER_FEE_FUNDS"
                                    );
                                    takerFeeToken.transferFrom(msg.sender, order.feeRecipientAddress, takerFee);
                                    fillResults.makerAssetFilledAmount = makerAssetFilledAmount;
                                    fillResults.takerAssetFilledAmount = takerAssetFillAmount;
                                    fillResults.makerFeePaid = uint256(-1);
                                    fillResults.takerFeePaid = takerFee;
                                    fillResults.protocolFeePaid = protocolFee;
                                }
                                function encodeBehaviorData(FillBehavior calldata behavior)
                                    external
                                    pure
                                    returns (bytes memory encoded)
                                {
                                    return abi.encode(behavior);
                                }
                                function protocolFeeMultiplier()
                                    external
                                    pure
                                    returns (uint256)
                                {
                                    return PROTOCOL_FEE_MULTIPLIER;
                                }
                                function getAssetProxy(bytes4)
                                    external
                                    view
                                    returns (address)
                                {
                                    return address(this);
                                }
                                function _getTokenFromAssetData(bytes memory assetData)
                                    private
                                    pure
                                    returns (TestMintableERC20Token token)
                                {
                                    return TestMintableERC20Token(LibBytesV06.readAddress(assetData, 16));
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            contract TestMintableERC20Token {
                                mapping(address => uint256) public balanceOf;
                                mapping(address => mapping(address => uint256)) public allowance;
                                function transfer(address to, uint256 amount)
                                    external
                                    virtual
                                    returns (bool)
                                {
                                    return transferFrom(msg.sender, to, amount);
                                }
                                function approve(address spender, uint256 amount)
                                    external
                                    virtual
                                    returns (bool)
                                {
                                    allowance[msg.sender][spender] = amount;
                                    return true;
                                }
                                function mint(address owner, uint256 amount)
                                    external
                                    virtual
                                {
                                    balanceOf[owner] += amount;
                                }
                                function burn(address owner, uint256 amount)
                                    external
                                    virtual
                                {
                                    require(balanceOf[owner] >= amount, "TestMintableERC20Token/INSUFFICIENT_FUNDS");
                                    balanceOf[owner] -= amount;
                                }
                                function transferFrom(address from, address to, uint256 amount)
                                    public
                                    virtual
                                    returns (bool)
                                {
                                    if (from != msg.sender) {
                                        require(
                                            allowance[from][msg.sender] >= amount,
                                            "TestMintableERC20Token/INSUFFICIENT_ALLOWANCE"
                                        );
                                        allowance[from][msg.sender] -= amount;
                                    }
                                    require(balanceOf[from] >= amount, "TestMintableERC20Token/INSUFFICIENT_FUNDS");
                                    balanceOf[from] -= amount;
                                    balanceOf[to] += amount;
                                    return true;
                                }
                                function getSpendableAmount(address owner, address spender)
                                    external
                                    view
                                    returns (uint256)
                                {
                                    return balanceOf[owner] < allowance[owner][spender]
                                        ? balanceOf[owner]
                                        : allowance[owner][spender];
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/transformers/IERC20Transformer.sol";
                            import "./TestMintableERC20Token.sol";
                            import "./TestTransformerHost.sol";
                            contract TestFillQuoteTransformerHost is
                                TestTransformerHost
                            {
                                function executeTransform(
                                    IERC20Transformer transformer,
                                    TestMintableERC20Token inputToken,
                                    uint256 inputTokenAmount,
                                    bytes calldata data
                                )
                                    external
                                    payable
                                {
                                    if (inputTokenAmount != 0) {
                                        inputToken.mint(address(this), inputTokenAmount);
                                    }
                                    // Have to make this call externally because transformers aren't payable.
                                    this.rawExecuteTransform(transformer, bytes32(0), msg.sender, data);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "../src/transformers/IERC20Transformer.sol";
                            import "../src/transformers/LibERC20Transformer.sol";
                            contract TestTransformerHost {
                                using LibERC20Transformer for IERC20TokenV06;
                                using LibRichErrorsV06 for bytes;
                                function rawExecuteTransform(
                                    IERC20Transformer transformer,
                                    bytes32 callDataHash,
                                    address taker,
                                    bytes calldata data
                                )
                                    external
                                {
                                    (bool _success, bytes memory resultData) =
                                        address(transformer).delegatecall(abi.encodeWithSelector(
                                            transformer.transform.selector,
                                            callDataHash,
                                            taker,
                                            data
                                        ));
                                    if (!_success) {
                                        resultData.rrevert();
                                    }
                                    require(
                                        abi.decode(resultData, (bytes4)) == LibERC20Transformer.TRANSFORMER_SUCCESS,
                                        "TestTransformerHost/INVALID_TRANSFORMER_RESULT"
                                    );
                                }
                                // solhint-disable
                                receive() external payable {}
                                // solhint-enable
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/ZeroEx.sol";
                            import "../src/features/IBootstrap.sol";
                            import "../src/migrations/FullMigration.sol";
                            contract TestFullMigration is
                                FullMigration
                            {
                                address public dieRecipient;
                                // solhint-disable-next-line no-empty-blocks
                                constructor(address payable deployer) public FullMigration(deployer) {}
                                function die(address payable ethRecipient) external override {
                                    dieRecipient = ethRecipient;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/ZeroEx.sol";
                            import "../src/features/IBootstrap.sol";
                            import "../src/migrations/InitialMigration.sol";
                            contract TestInitialMigration is
                                InitialMigration
                            {
                                address public bootstrapFeature;
                                address public dieRecipient;
                                // solhint-disable-next-line no-empty-blocks
                                constructor(address deployer) public InitialMigration(deployer) {}
                                function callBootstrap(ZeroEx zeroEx) external {
                                    IBootstrap(address(zeroEx)).bootstrap(address(this), new bytes(0));
                                }
                                function bootstrap(address owner, BootstrapFeatures memory features)
                                    public
                                    override
                                    returns (bytes4 success)
                                {
                                    success = InitialMigration.bootstrap(owner, features);
                                    // Snoop the bootstrap feature contract.
                                    bootstrapFeature = ZeroEx(address(uint160(address(this))))
                                        .getFunctionImplementation(IBootstrap.bootstrap.selector);
                                }
                                function die(address payable ethRecipient) public override {
                                    dieRecipient = ethRecipient;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/features/TransformERC20.sol";
                            contract TestMetaTransactionsTransformERC20Feature is
                                TransformERC20
                            {
                                event TransformERC20Called(
                                    address sender,
                                    uint256 value,
                                    bytes32 callDataHash,
                                    address taker,
                                    IERC20TokenV06 inputToken,
                                    IERC20TokenV06 outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 minOutputTokenAmount,
                                    Transformation[] transformations
                                );
                                function _transformERC20(
                                    bytes32 callDataHash,
                                    address payable taker,
                                    IERC20TokenV06 inputToken,
                                    IERC20TokenV06 outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 minOutputTokenAmount,
                                    Transformation[] memory transformations
                                )
                                    public
                                    override
                                    payable
                                    returns (uint256 outputTokenAmount)
                                {
                                    if (msg.value == 666) {
                                        revert('FAIL');
                                    }
                                    emit TransformERC20Called(
                                        msg.sender,
                                        msg.value,
                                        callDataHash,
                                        taker,
                                        inputToken,
                                        outputToken,
                                        inputTokenAmount,
                                        minOutputTokenAmount,
                                        transformations
                                    );
                                    return 1337;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/migrations/LibMigrate.sol";
                            import "../src/features/IOwnable.sol";
                            contract TestMigrator {
                                event TestMigrateCalled(
                                    bytes callData,
                                    address owner
                                );
                                function succeedingMigrate() external returns (bytes4 success) {
                                    emit TestMigrateCalled(
                                        msg.data,
                                        IOwnable(address(this)).owner()
                                    );
                                    return LibMigrate.MIGRATE_SUCCESS;
                                }
                                function failingMigrate() external returns (bytes4 success) {
                                    emit TestMigrateCalled(
                                        msg.data,
                                        IOwnable(address(this)).owner()
                                    );
                                    return 0xdeadbeef;
                                }
                                function revertingMigrate() external pure {
                                    revert("OOPSIE");
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/contracts/src/v06/IERC20TokenV06.sol";
                            import "../src/transformers/IERC20Transformer.sol";
                            import "../src/transformers/LibERC20Transformer.sol";
                            import "./TestMintableERC20Token.sol";
                            contract TestMintTokenERC20Transformer is
                                IERC20Transformer
                            {
                                struct TransformData {
                                    IERC20TokenV06 inputToken;
                                    TestMintableERC20Token outputToken;
                                    uint256 burnAmount;
                                    uint256 mintAmount;
                                    uint256 feeAmount;
                                }
                                event MintTransform(
                                    address context,
                                    address caller,
                                    bytes32 callDataHash,
                                    address taker,
                                    bytes data,
                                    uint256 inputTokenBalance,
                                    uint256 ethBalance
                                );
                                function transform(
                                    bytes32 callDataHash,
                                    address payable taker,
                                    bytes calldata data_
                                )
                                    external
                                    override
                                    returns (bytes4 success)
                                {
                                    TransformData memory data = abi.decode(data_, (TransformData));
                                    emit MintTransform(
                                        address(this),
                                        msg.sender,
                                        callDataHash,
                                        taker,
                                        data_,
                                        data.inputToken.balanceOf(address(this)),
                                        address(this).balance
                                    );
                                    // "Burn" input tokens.
                                    data.inputToken.transfer(address(0), data.burnAmount);
                                    // Mint output tokens.
                                    if (LibERC20Transformer.isTokenETH(IERC20TokenV06(address(data.outputToken)))) {
                                        taker.transfer(data.mintAmount);
                                    } else {
                                        data.outputToken.mint(
                                            taker,
                                            data.mintAmount
                                        );
                                        // Burn fees from output.
                                        data.outputToken.burn(taker, data.feeAmount);
                                    }
                                    return LibERC20Transformer.TRANSFORMER_SUCCESS;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/fixins/FixinCommon.sol";
                            contract TestSimpleFunctionRegistryFeatureImpl1 is
                                FixinCommon
                            {
                                function testFn()
                                    external
                                    pure
                                    returns (uint256 id)
                                {
                                    return 1337;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/fixins/FixinCommon.sol";
                            contract TestSimpleFunctionRegistryFeatureImpl2 is
                                FixinCommon
                            {
                                function testFn()
                                    external
                                    pure
                                    returns (uint256 id)
                                {
                                    return 1338;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/features/TokenSpender.sol";
                            contract TestTokenSpender is
                                TokenSpender
                            {
                                modifier onlySelf() override {
                                    _;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "./TestMintableERC20Token.sol";
                            contract TestTokenSpenderERC20Token is
                                TestMintableERC20Token
                            {
                                event TransferFromCalled(
                                    address sender,
                                    address from,
                                    address to,
                                    uint256 amount
                                );
                                // `transferFrom()` behavior depends on the value of `amount`.
                                uint256 constant private EMPTY_RETURN_AMOUNT = 1337;
                                uint256 constant private FALSE_RETURN_AMOUNT = 1338;
                                uint256 constant private REVERT_RETURN_AMOUNT = 1339;
                                function transferFrom(address from, address to, uint256 amount)
                                    public
                                    override
                                    returns (bool)
                                {
                                    emit TransferFromCalled(msg.sender, from, to, amount);
                                    if (amount == EMPTY_RETURN_AMOUNT) {
                                        assembly { return(0, 0) }
                                    }
                                    if (amount == FALSE_RETURN_AMOUNT) {
                                        return false;
                                    }
                                    if (amount == REVERT_RETURN_AMOUNT) {
                                        revert("TestTokenSpenderERC20Token/Revert");
                                    }
                                    return true;
                                }
                                function setBalanceAndAllowanceOf(
                                    address owner,
                                    uint256 balance,
                                    address spender,
                                    uint256 allowance_
                                )
                                    external
                                {
                                    balanceOf[owner] = balance;
                                    allowance[owner][spender] = allowance_;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/features/TransformERC20.sol";
                            contract TestTransformERC20 is
                                TransformERC20
                            {
                                // solhint-disable no-empty-blocks
                                constructor()
                                    TransformERC20()
                                    public
                                {}
                                modifier onlySelf() override {
                                    _;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/transformers/Transformer.sol";
                            import "../src/transformers/LibERC20Transformer.sol";
                            contract TestTransformerBase is
                                Transformer
                            {
                                function transform(
                                    bytes32,
                                    address payable,
                                    bytes calldata
                                )
                                    external
                                    override
                                    returns (bytes4 success)
                                {
                                    return LibERC20Transformer.TRANSFORMER_SUCCESS;
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/transformers/LibERC20Transformer.sol";
                            contract TestTransformerDeployerTransformer {
                                address payable public immutable deployer;
                                constructor() public payable {
                                    deployer = msg.sender;
                                }
                                modifier onlyDeployer() {
                                    require(msg.sender == deployer, "TestTransformerDeployerTransformer/ONLY_DEPLOYER");
                                    _;
                                }
                                function die()
                                    external
                                    onlyDeployer
                                {
                                    selfdestruct(deployer);
                                }
                                function isDeployedByDeployer(uint32 nonce)
                                    external
                                    view
                                    returns (bool)
                                {
                                    return LibERC20Transformer.getDeployedAddress(deployer, nonce) == address(this);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "./TestMintableERC20Token.sol";
                            contract TestWeth is
                                TestMintableERC20Token
                            {
                                function deposit()
                                    external
                                    payable
                                {
                                    this.mint(msg.sender, msg.value);
                                }
                                function withdraw(uint256 amount)
                                    external
                                {
                                    require(balanceOf[msg.sender] >= amount, "TestWeth/INSUFFICIENT_FUNDS");
                                    balanceOf[msg.sender] -= amount;
                                    msg.sender.transfer(amount);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/transformers/IERC20Transformer.sol";
                            import "./TestMintableERC20Token.sol";
                            import "./TestTransformerHost.sol";
                            import "./TestWeth.sol";
                            contract TestWethTransformerHost is
                                TestTransformerHost
                            {
                                // solhint-disable
                                TestWeth private immutable _weth;
                                // solhint-enable
                                constructor(TestWeth weth) public {
                                    _weth = weth;
                                }
                                function executeTransform(
                                    uint256 wethAmount,
                                    IERC20Transformer transformer,
                                    bytes calldata data
                                )
                                    external
                                    payable
                                {
                                    if (wethAmount != 0) {
                                        _weth.deposit{value: wethAmount}();
                                    }
                                    // Have to make this call externally because transformers aren't payable.
                                    this.rawExecuteTransform(transformer, bytes32(0), msg.sender, data);
                                }
                            }
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../src/fixins/FixinCommon.sol";
                            import "../src/ZeroEx.sol";
                            contract TestZeroExFeature is
                                FixinCommon
                            {
                                event PayableFnCalled(uint256 value);
                                event NotPayableFnCalled();
                                function payableFn()
                                    external
                                    payable
                                {
                                    emit PayableFnCalled(msg.value);
                                }
                                function notPayableFn()
                                    external
                                {
                                    emit NotPayableFnCalled();
                                }
                                // solhint-disable no-empty-blocks
                                function unimplmentedFn()
                                    external
                                {}
                                function internalFn()
                                    external
                                    onlySelf
                                {}
                            }
                            

                            File 6 of 9: FillQuoteTransformer
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibMathV06.sol";
                            import "../errors/LibTransformERC20RichErrors.sol";
                            import "../features/interfaces/INativeOrdersFeature.sol";
                            import "../features/libs/LibNativeOrder.sol";
                            import "./bridges/IBridgeAdapter.sol";
                            import "./Transformer.sol";
                            import "./LibERC20Transformer.sol";
                            import "../IZeroEx.sol";
                            /// @dev A transformer that fills an ERC20 market sell/buy quote.
                            ///      This transformer shortcuts bridge orders and fills them directly
                            contract FillQuoteTransformer is Transformer {
                                using LibERC20TokenV06 for IERC20Token;
                                using LibERC20Transformer for IERC20Token;
                                using LibSafeMathV06 for uint256;
                                using LibSafeMathV06 for uint128;
                                using LibRichErrorsV06 for bytes;
                                /// @dev Whether we are performing a market sell or buy.
                                enum Side {
                                    Sell,
                                    Buy
                                }
                                enum OrderType {
                                    Bridge,
                                    Limit,
                                    Rfq,
                                    Otc
                                }
                                struct LimitOrderInfo {
                                    LibNativeOrder.LimitOrder order;
                                    LibSignature.Signature signature;
                                    // Maximum taker token amount of this limit order to fill.
                                    uint256 maxTakerTokenFillAmount;
                                }
                                struct RfqOrderInfo {
                                    LibNativeOrder.RfqOrder order;
                                    LibSignature.Signature signature;
                                    // Maximum taker token amount of this limit order to fill.
                                    uint256 maxTakerTokenFillAmount;
                                }
                                struct OtcOrderInfo {
                                    LibNativeOrder.OtcOrder order;
                                    LibSignature.Signature signature;
                                    // Maximum taker token amount of this limit order to fill.
                                    uint256 maxTakerTokenFillAmount;
                                }
                                /// @dev Transform data to ABI-encode and pass into `transform()`.
                                struct TransformData {
                                    // Whether we are performing a market sell or buy.
                                    Side side;
                                    // The token being sold.
                                    // This should be an actual token, not the ETH pseudo-token.
                                    IERC20Token sellToken;
                                    // The token being bought.
                                    // This should be an actual token, not the ETH pseudo-token.
                                    IERC20Token buyToken;
                                    // External liquidity bridge orders. Sorted by fill sequence.
                                    IBridgeAdapter.BridgeOrder[] bridgeOrders;
                                    // Native limit orders. Sorted by fill sequence.
                                    LimitOrderInfo[] limitOrders;
                                    // Native RFQ orders. Sorted by fill sequence.
                                    RfqOrderInfo[] rfqOrders;
                                    // The sequence to fill the orders in. Each item will fill the next
                                    // order of that type in either `bridgeOrders`, `limitOrders`,
                                    // or `rfqOrders.`
                                    OrderType[] fillSequence;
                                    // Amount of `sellToken` to sell or `buyToken` to buy.
                                    // For sells, setting the high-bit indicates that
                                    // `sellAmount & LOW_BITS` should be treated as a `1e18` fraction of
                                    // the current balance of `sellToken`, where
                                    // `1e18+ == 100%` and `0.5e18 == 50%`, etc.
                                    uint256 fillAmount;
                                    // Who to transfer unused protocol fees to.
                                    // May be a valid address or one of:
                                    // `address(0)`: Stay in flash wallet.
                                    // `address(1)`: Send to the taker.
                                    // `address(2)`: Send to the sender (caller of `transformERC20()`).
                                    address payable refundReceiver;
                                    // Otc orders. Sorted by fill sequence.
                                    OtcOrderInfo[] otcOrders;
                                }
                                struct FillOrderResults {
                                    // The amount of taker tokens sold, according to balance checks.
                                    uint256 takerTokenSoldAmount;
                                    // The amount of maker tokens sold, according to balance checks.
                                    uint256 makerTokenBoughtAmount;
                                    // The amount of protocol fee paid.
                                    uint256 protocolFeePaid;
                                }
                                /// @dev Intermediate state variables to get around stack limits.
                                struct FillState {
                                    uint256 ethRemaining;
                                    uint256 boughtAmount;
                                    uint256 soldAmount;
                                    uint256 protocolFee;
                                    uint256 takerTokenBalanceRemaining;
                                    uint256[4] currentIndices;
                                    OrderType currentOrderType;
                                }
                                /// @dev Emitted when a trade is skipped due to a lack of funds
                                ///      to pay the 0x Protocol fee.
                                /// @param orderHash The hash of the order that was skipped.
                                event ProtocolFeeUnfunded(bytes32 orderHash);
                                /// @dev The highest bit of a uint256 value.
                                uint256 private constant HIGH_BIT = 2 ** 255;
                                /// @dev Mask of the lower 255 bits of a uint256 value.
                                uint256 private constant LOWER_255_BITS = HIGH_BIT - 1;
                                /// @dev If `refundReceiver` is set to this address, unpsent
                                ///      protocol fees will be sent to the transform recipient.
                                address private constant REFUND_RECEIVER_RECIPIENT = address(1);
                                /// @dev If `refundReceiver` is set to this address, unpsent
                                ///      protocol fees will be sent to the sender.
                                address private constant REFUND_RECEIVER_SENDER = address(2);
                                /// @dev The BridgeAdapter address
                                IBridgeAdapter public immutable bridgeAdapter;
                                /// @dev The exchange proxy contract.
                                IZeroEx public immutable zeroEx;
                                /// @dev Create this contract.
                                /// @param bridgeAdapter_ The bridge adapter contract.
                                /// @param zeroEx_ The Exchange Proxy contract.
                                constructor(IBridgeAdapter bridgeAdapter_, IZeroEx zeroEx_) public Transformer() {
                                    bridgeAdapter = bridgeAdapter_;
                                    zeroEx = zeroEx_;
                                }
                                /// @dev Sell this contract's entire balance of of `sellToken` in exchange
                                ///      for `buyToken` by filling `orders`. Protocol fees should be attached
                                ///      to this call. `buyToken` and excess ETH will be transferred back to the caller.
                                /// @param context Context information.
                                /// @return magicBytes The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
                                /* solhint-disable function-max-lines */
                                function transform(TransformContext calldata context) external override returns (bytes4 magicBytes) {
                                    TransformData memory data = abi.decode(context.data, (TransformData));
                                    FillState memory state;
                                    // Validate data fields.
                                    if (data.sellToken.isTokenETH() || data.buyToken.isTokenETH()) {
                                        LibTransformERC20RichErrors
                                            .InvalidTransformDataError(
                                                LibTransformERC20RichErrors.InvalidTransformDataErrorCode.INVALID_TOKENS,
                                                context.data
                                            )
                                            .rrevert();
                                    }
                                    if (
                                        data.bridgeOrders.length + data.limitOrders.length + data.rfqOrders.length + data.otcOrders.length !=
                                        data.fillSequence.length
                                    ) {
                                        LibTransformERC20RichErrors
                                            .InvalidTransformDataError(
                                                LibTransformERC20RichErrors.InvalidTransformDataErrorCode.INVALID_ARRAY_LENGTH,
                                                context.data
                                            )
                                            .rrevert();
                                    }
                                    state.takerTokenBalanceRemaining = data.sellToken.getTokenBalanceOf(address(this));
                                    if (data.side == Side.Sell) {
                                        data.fillAmount = _normalizeFillAmount(data.fillAmount, state.takerTokenBalanceRemaining);
                                    }
                                    // Approve the exchange proxy to spend our sell tokens if native orders
                                    // are present.
                                    if (data.limitOrders.length + data.rfqOrders.length + data.otcOrders.length != 0) {
                                        data.sellToken.approveIfBelow(address(zeroEx), data.fillAmount);
                                        // Compute the protocol fee if a limit order is present.
                                        if (data.limitOrders.length != 0) {
                                            state.protocolFee = uint256(zeroEx.getProtocolFeeMultiplier()).safeMul(tx.gasprice);
                                        }
                                    }
                                    state.ethRemaining = address(this).balance;
                                    // Fill the orders.
                                    for (uint256 i = 0; i < data.fillSequence.length; ++i) {
                                        // Check if we've hit our targets.
                                        if (data.side == Side.Sell) {
                                            // Market sell check.
                                            if (state.soldAmount >= data.fillAmount) {
                                                break;
                                            }
                                        } else {
                                            // Market buy check.
                                            if (state.boughtAmount >= data.fillAmount) {
                                                break;
                                            }
                                        }
                                        state.currentOrderType = OrderType(data.fillSequence[i]);
                                        uint256 orderIndex = state.currentIndices[uint256(state.currentOrderType)];
                                        // Fill the order.
                                        FillOrderResults memory results;
                                        if (state.currentOrderType == OrderType.Bridge) {
                                            results = _fillBridgeOrder(data.bridgeOrders[orderIndex], data, state);
                                        } else if (state.currentOrderType == OrderType.Limit) {
                                            results = _fillLimitOrder(data.limitOrders[orderIndex], data, state);
                                        } else if (state.currentOrderType == OrderType.Rfq) {
                                            results = _fillRfqOrder(data.rfqOrders[orderIndex], data, state);
                                        } else if (state.currentOrderType == OrderType.Otc) {
                                            results = _fillOtcOrder(data.otcOrders[orderIndex], data, state);
                                        } else {
                                            revert("INVALID_ORDER_TYPE");
                                        }
                                        // Accumulate totals.
                                        state.soldAmount = state.soldAmount.safeAdd(results.takerTokenSoldAmount);
                                        state.boughtAmount = state.boughtAmount.safeAdd(results.makerTokenBoughtAmount);
                                        state.ethRemaining = state.ethRemaining.safeSub(results.protocolFeePaid);
                                        state.takerTokenBalanceRemaining = state.takerTokenBalanceRemaining.safeSub(results.takerTokenSoldAmount);
                                        state.currentIndices[uint256(state.currentOrderType)]++;
                                    }
                                    // Ensure we hit our targets.
                                    if (data.side == Side.Sell) {
                                        // Market sell check.
                                        if (state.soldAmount < data.fillAmount) {
                                            LibTransformERC20RichErrors
                                                .IncompleteFillSellQuoteError(address(data.sellToken), state.soldAmount, data.fillAmount)
                                                .rrevert();
                                        }
                                    } else {
                                        // Market buy check.
                                        if (state.boughtAmount < data.fillAmount) {
                                            LibTransformERC20RichErrors
                                                .IncompleteFillBuyQuoteError(address(data.buyToken), state.boughtAmount, data.fillAmount)
                                                .rrevert();
                                        }
                                    }
                                    // Refund unspent protocol fees.
                                    if (state.ethRemaining > 0 && data.refundReceiver != address(0)) {
                                        bool transferSuccess;
                                        if (data.refundReceiver == REFUND_RECEIVER_RECIPIENT) {
                                            (transferSuccess, ) = context.recipient.call{value: state.ethRemaining}("");
                                        } else if (data.refundReceiver == REFUND_RECEIVER_SENDER) {
                                            (transferSuccess, ) = context.sender.call{value: state.ethRemaining}("");
                                        } else {
                                            (transferSuccess, ) = data.refundReceiver.call{value: state.ethRemaining}("");
                                        }
                                        require(transferSuccess, "FillQuoteTransformer/ETHER_TRANSFER_FALIED");
                                    }
                                    return LibERC20Transformer.TRANSFORMER_SUCCESS;
                                }
                                /* solhint-enable function-max-lines */
                                // Fill a single bridge order.
                                function _fillBridgeOrder(
                                    IBridgeAdapter.BridgeOrder memory order,
                                    TransformData memory data,
                                    FillState memory state
                                ) private returns (FillOrderResults memory results) {
                                    uint256 takerTokenFillAmount = _computeTakerTokenFillAmount(
                                        data,
                                        state,
                                        order.takerTokenAmount,
                                        order.makerTokenAmount,
                                        0
                                    );
                                    (bool success, bytes memory resultData) = address(bridgeAdapter).delegatecall(
                                        abi.encodeWithSelector(
                                            IBridgeAdapter.trade.selector,
                                            order,
                                            data.sellToken,
                                            data.buyToken,
                                            takerTokenFillAmount
                                        )
                                    );
                                    if (success) {
                                        results.makerTokenBoughtAmount = abi.decode(resultData, (uint256));
                                        results.takerTokenSoldAmount = takerTokenFillAmount;
                                    }
                                }
                                // Fill a single limit order.
                                function _fillLimitOrder(
                                    LimitOrderInfo memory orderInfo,
                                    TransformData memory data,
                                    FillState memory state
                                ) private returns (FillOrderResults memory results) {
                                    uint256 takerTokenFillAmount = LibSafeMathV06.min256(
                                        _computeTakerTokenFillAmount(
                                            data,
                                            state,
                                            orderInfo.order.takerAmount,
                                            orderInfo.order.makerAmount,
                                            orderInfo.order.takerTokenFeeAmount
                                        ),
                                        orderInfo.maxTakerTokenFillAmount
                                    );
                                    // Emit an event if we do not have sufficient ETH to cover the protocol fee.
                                    if (state.ethRemaining < state.protocolFee) {
                                        bytes32 orderHash = zeroEx.getLimitOrderHash(orderInfo.order);
                                        emit ProtocolFeeUnfunded(orderHash);
                                        return results; // Empty results.
                                    }
                                    try
                                        zeroEx.fillLimitOrder{value: state.protocolFee}(
                                            orderInfo.order,
                                            orderInfo.signature,
                                            takerTokenFillAmount.safeDowncastToUint128()
                                        )
                                    returns (uint128 takerTokenFilledAmount, uint128 makerTokenFilledAmount) {
                                        if (orderInfo.order.takerTokenFeeAmount > 0) {
                                            takerTokenFilledAmount = takerTokenFilledAmount.safeAdd128(
                                                LibMathV06
                                                    .getPartialAmountFloor(
                                                        takerTokenFilledAmount,
                                                        orderInfo.order.takerAmount,
                                                        orderInfo.order.takerTokenFeeAmount
                                                    )
                                                    .safeDowncastToUint128()
                                            );
                                        }
                                        results.takerTokenSoldAmount = takerTokenFilledAmount;
                                        results.makerTokenBoughtAmount = makerTokenFilledAmount;
                                        results.protocolFeePaid = state.protocolFee;
                                    } catch {}
                                }
                                // Fill a single RFQ order.
                                function _fillRfqOrder(
                                    RfqOrderInfo memory orderInfo,
                                    TransformData memory data,
                                    FillState memory state
                                ) private returns (FillOrderResults memory results) {
                                    uint256 takerTokenFillAmount = LibSafeMathV06.min256(
                                        _computeTakerTokenFillAmount(data, state, orderInfo.order.takerAmount, orderInfo.order.makerAmount, 0),
                                        orderInfo.maxTakerTokenFillAmount
                                    );
                                    try
                                        zeroEx.fillRfqOrder(orderInfo.order, orderInfo.signature, takerTokenFillAmount.safeDowncastToUint128())
                                    returns (uint128 takerTokenFilledAmount, uint128 makerTokenFilledAmount) {
                                        results.takerTokenSoldAmount = takerTokenFilledAmount;
                                        results.makerTokenBoughtAmount = makerTokenFilledAmount;
                                    } catch {}
                                }
                                // Fill a single OTC order.
                                function _fillOtcOrder(
                                    OtcOrderInfo memory orderInfo,
                                    TransformData memory data,
                                    FillState memory state
                                ) private returns (FillOrderResults memory results) {
                                    uint256 takerTokenFillAmount = LibSafeMathV06.min256(
                                        _computeTakerTokenFillAmount(data, state, orderInfo.order.takerAmount, orderInfo.order.makerAmount, 0),
                                        orderInfo.maxTakerTokenFillAmount
                                    );
                                    try
                                        zeroEx.fillOtcOrder(orderInfo.order, orderInfo.signature, takerTokenFillAmount.safeDowncastToUint128())
                                    returns (uint128 takerTokenFilledAmount, uint128 makerTokenFilledAmount) {
                                        results.takerTokenSoldAmount = takerTokenFilledAmount;
                                        results.makerTokenBoughtAmount = makerTokenFilledAmount;
                                    } catch {
                                        revert("FillQuoteTransformer/OTC_ORDER_FILL_FAILED");
                                    }
                                }
                                // Compute the next taker token fill amount of a generic order.
                                function _computeTakerTokenFillAmount(
                                    TransformData memory data,
                                    FillState memory state,
                                    uint256 orderTakerAmount,
                                    uint256 orderMakerAmount,
                                    uint256 orderTakerTokenFeeAmount
                                ) private pure returns (uint256 takerTokenFillAmount) {
                                    if (data.side == Side.Sell) {
                                        takerTokenFillAmount = data.fillAmount.safeSub(state.soldAmount);
                                        if (orderTakerTokenFeeAmount != 0) {
                                            takerTokenFillAmount = LibMathV06.getPartialAmountCeil(
                                                takerTokenFillAmount,
                                                orderTakerAmount.safeAdd(orderTakerTokenFeeAmount),
                                                orderTakerAmount
                                            );
                                        }
                                    } else {
                                        // Buy
                                        takerTokenFillAmount = LibMathV06.getPartialAmountCeil(
                                            data.fillAmount.safeSub(state.boughtAmount),
                                            orderMakerAmount,
                                            orderTakerAmount
                                        );
                                    }
                                    return
                                        LibSafeMathV06.min256(
                                            LibSafeMathV06.min256(takerTokenFillAmount, orderTakerAmount),
                                            state.takerTokenBalanceRemaining
                                        );
                                }
                                // Convert possible proportional values to absolute quantities.
                                function _normalizeFillAmount(uint256 rawAmount, uint256 balance) private pure returns (uint256 normalized) {
                                    if ((rawAmount & HIGH_BIT) == HIGH_BIT) {
                                        // If the high bit of `rawAmount` is set then the lower 255 bits
                                        // specify a fraction of `balance`.
                                        return
                                            LibSafeMathV06.min256(
                                                (balance * LibSafeMathV06.min256(rawAmount & LOWER_255_BITS, 1e18)) / 1e18,
                                                balance
                                            );
                                    }
                                    return rawAmount;
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibRichErrorsV06 {
                                // bytes4(keccak256("Error(string)"))
                                bytes4 internal constant STANDARD_ERROR_SELECTOR = 0x08c379a0;
                                /// @dev ABI encode a standard, string revert error payload.
                                ///      This is the same payload that would be included by a `revert(string)`
                                ///      solidity statement. It has the function signature `Error(string)`.
                                /// @param message The error string.
                                /// @return The ABI encoded error.
                                function StandardError(string memory message) internal pure returns (bytes memory) {
                                    return abi.encodeWithSelector(STANDARD_ERROR_SELECTOR, bytes(message));
                                }
                                /// @dev Reverts an encoded rich revert reason `errorData`.
                                /// @param errorData ABI encoded error data.
                                function rrevert(bytes memory errorData) internal pure {
                                    assembly {
                                        revert(add(errorData, 0x20), mload(errorData))
                                    }
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity >=0.6.5 <0.9;
                            interface IERC20Token {
                                event Transfer(address indexed from, address indexed to, uint256 value);
                                event Approval(address indexed owner, address indexed spender, uint256 value);
                                /// @dev send `value` token to `to` from `msg.sender`
                                /// @param to The address of the recipient
                                /// @param value The amount of token to be transferred
                                /// @return True if transfer was successful
                                function transfer(address to, uint256 value) external returns (bool);
                                /// @dev send `value` token to `to` from `from` on the condition it is approved by `from`
                                /// @param from The address of the sender
                                /// @param to The address of the recipient
                                /// @param value The amount of token to be transferred
                                /// @return True if transfer was successful
                                function transferFrom(address from, address to, uint256 value) external returns (bool);
                                /// @dev `msg.sender` approves `spender` to spend `value` tokens
                                /// @param spender The address of the account able to transfer the tokens
                                /// @param value The amount of wei to be approved for transfer
                                /// @return Always true if the call has enough gas to complete execution
                                function approve(address spender, uint256 value) external returns (bool);
                                /// @dev Query total supply of token
                                /// @return Total supply of token
                                function totalSupply() external view returns (uint256);
                                /// @dev Get the balance of `owner`.
                                /// @param owner The address from which the balance will be retrieved
                                /// @return Balance of owner
                                function balanceOf(address owner) external view returns (uint256);
                                /// @dev Get the allowance for `spender` to spend from `owner`.
                                /// @param owner The address of the account owning tokens
                                /// @param spender The address of the account able to transfer the tokens
                                /// @return Amount of remaining tokens allowed to spent
                                function allowance(address owner, address spender) external view returns (uint256);
                                /// @dev Get the number of decimals this token has.
                                function decimals() external view returns (uint8);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
                            import "../IERC20Token.sol";
                            library LibERC20TokenV06 {
                                bytes private constant DECIMALS_CALL_DATA = hex"313ce567";
                                /// @dev Calls `IERC20Token(token).approve()`.
                                ///      Reverts if the return data is invalid or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param spender The address that receives an allowance.
                                /// @param allowance The allowance to set.
                                function compatApprove(IERC20Token token, address spender, uint256 allowance) internal {
                                    bytes memory callData = abi.encodeWithSelector(token.approve.selector, spender, allowance);
                                    _callWithOptionalBooleanResult(address(token), callData);
                                }
                                /// @dev Calls `IERC20Token(token).approve()` and sets the allowance to the
                                ///      maximum if the current approval is not already >= an amount.
                                ///      Reverts if the return data is invalid or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param spender The address that receives an allowance.
                                /// @param amount The minimum allowance needed.
                                function approveIfBelow(IERC20Token token, address spender, uint256 amount) internal {
                                    if (token.allowance(address(this), spender) < amount) {
                                        compatApprove(token, spender, uint256(-1));
                                    }
                                }
                                /// @dev Calls `IERC20Token(token).transfer()`.
                                ///      Reverts if the return data is invalid or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param to The address that receives the tokens
                                /// @param amount Number of tokens to transfer.
                                function compatTransfer(IERC20Token token, address to, uint256 amount) internal {
                                    bytes memory callData = abi.encodeWithSelector(token.transfer.selector, to, amount);
                                    _callWithOptionalBooleanResult(address(token), callData);
                                }
                                /// @dev Calls `IERC20Token(token).transferFrom()`.
                                ///      Reverts if the return data is invalid or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param from The owner of the tokens.
                                /// @param to The address that receives the tokens
                                /// @param amount Number of tokens to transfer.
                                function compatTransferFrom(IERC20Token token, address from, address to, uint256 amount) internal {
                                    bytes memory callData = abi.encodeWithSelector(token.transferFrom.selector, from, to, amount);
                                    _callWithOptionalBooleanResult(address(token), callData);
                                }
                                /// @dev Retrieves the number of decimals for a token.
                                ///      Returns `18` if the call reverts.
                                /// @param token The address of the token contract.
                                /// @return tokenDecimals The number of decimals places for the token.
                                function compatDecimals(IERC20Token token) internal view returns (uint8 tokenDecimals) {
                                    tokenDecimals = 18;
                                    (bool didSucceed, bytes memory resultData) = address(token).staticcall(DECIMALS_CALL_DATA);
                                    if (didSucceed && resultData.length >= 32) {
                                        tokenDecimals = uint8(LibBytesV06.readUint256(resultData, 0));
                                    }
                                }
                                /// @dev Retrieves the allowance for a token, owner, and spender.
                                ///      Returns `0` if the call reverts.
                                /// @param token The address of the token contract.
                                /// @param owner The owner of the tokens.
                                /// @param spender The address the spender.
                                /// @return allowance_ The allowance for a token, owner, and spender.
                                function compatAllowance(
                                    IERC20Token token,
                                    address owner,
                                    address spender
                                ) internal view returns (uint256 allowance_) {
                                    (bool didSucceed, bytes memory resultData) = address(token).staticcall(
                                        abi.encodeWithSelector(token.allowance.selector, owner, spender)
                                    );
                                    if (didSucceed && resultData.length >= 32) {
                                        allowance_ = LibBytesV06.readUint256(resultData, 0);
                                    }
                                }
                                /// @dev Retrieves the balance for a token owner.
                                ///      Returns `0` if the call reverts.
                                /// @param token The address of the token contract.
                                /// @param owner The owner of the tokens.
                                /// @return balance The token balance of an owner.
                                function compatBalanceOf(IERC20Token token, address owner) internal view returns (uint256 balance) {
                                    (bool didSucceed, bytes memory resultData) = address(token).staticcall(
                                        abi.encodeWithSelector(token.balanceOf.selector, owner)
                                    );
                                    if (didSucceed && resultData.length >= 32) {
                                        balance = LibBytesV06.readUint256(resultData, 0);
                                    }
                                }
                                /// @dev Executes a call on address `target` with calldata `callData`
                                ///      and asserts that either nothing was returned or a single boolean
                                ///      was returned equal to `true`.
                                /// @param target The call target.
                                /// @param callData The abi-encoded call data.
                                function _callWithOptionalBooleanResult(address target, bytes memory callData) private {
                                    (bool didSucceed, bytes memory resultData) = target.call(callData);
                                    // Revert if the call reverted.
                                    if (!didSucceed) {
                                        LibRichErrorsV06.rrevert(resultData);
                                    }
                                    // If we get back 0 returndata, this may be a non-standard ERC-20 that
                                    // does not return a boolean. Check that it at least contains code.
                                    if (resultData.length == 0) {
                                        uint256 size;
                                        assembly {
                                            size := extcodesize(target)
                                        }
                                        require(size > 0, "invalid token address, contains no code");
                                        return;
                                    }
                                    // If we get back at least 32 bytes, we know the target address
                                    // contains code, and we assume it is a token that returned a boolean
                                    // success value, which must be true.
                                    if (resultData.length >= 32) {
                                        uint256 result = LibBytesV06.readUint256(resultData, 0);
                                        if (result == 1) {
                                            return;
                                        } else {
                                            LibRichErrorsV06.rrevert(resultData);
                                        }
                                    }
                                    // If 0 < returndatasize < 32, the target is a contract, but not a
                                    // valid token.
                                    LibRichErrorsV06.rrevert(resultData);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./errors/LibBytesRichErrorsV06.sol";
                            import "./errors/LibRichErrorsV06.sol";
                            library LibBytesV06 {
                                using LibBytesV06 for bytes;
                                /// @dev Gets the memory address for a byte array.
                                /// @param input Byte array to lookup.
                                /// @return memoryAddress Memory address of byte array. This
                                ///         points to the header of the byte array which contains
                                ///         the length.
                                function rawAddress(bytes memory input) internal pure returns (uint256 memoryAddress) {
                                    assembly {
                                        memoryAddress := input
                                    }
                                    return memoryAddress;
                                }
                                /// @dev Gets the memory address for the contents of a byte array.
                                /// @param input Byte array to lookup.
                                /// @return memoryAddress Memory address of the contents of the byte array.
                                function contentAddress(bytes memory input) internal pure returns (uint256 memoryAddress) {
                                    assembly {
                                        memoryAddress := add(input, 32)
                                    }
                                    return memoryAddress;
                                }
                                /// @dev Copies `length` bytes from memory location `source` to `dest`.
                                /// @param dest memory address to copy bytes to.
                                /// @param source memory address to copy bytes from.
                                /// @param length number of bytes to copy.
                                function memCopy(uint256 dest, uint256 source, uint256 length) internal pure {
                                    if (length < 32) {
                                        // Handle a partial word by reading destination and masking
                                        // off the bits we are interested in.
                                        // This correctly handles overlap, zero lengths and source == dest
                                        assembly {
                                            let mask := sub(exp(256, sub(32, length)), 1)
                                            let s := and(mload(source), not(mask))
                                            let d := and(mload(dest), mask)
                                            mstore(dest, or(s, d))
                                        }
                                    } else {
                                        // Skip the O(length) loop when source == dest.
                                        if (source == dest) {
                                            return;
                                        }
                                        // For large copies we copy whole words at a time. The final
                                        // word is aligned to the end of the range (instead of after the
                                        // previous) to handle partial words. So a copy will look like this:
                                        //
                                        //  ####
                                        //      ####
                                        //          ####
                                        //            ####
                                        //
                                        // We handle overlap in the source and destination range by
                                        // changing the copying direction. This prevents us from
                                        // overwriting parts of source that we still need to copy.
                                        //
                                        // This correctly handles source == dest
                                        //
                                        if (source > dest) {
                                            assembly {
                                                // We subtract 32 from `sEnd` and `dEnd` because it
                                                // is easier to compare with in the loop, and these
                                                // are also the addresses we need for copying the
                                                // last bytes.
                                                length := sub(length, 32)
                                                let sEnd := add(source, length)
                                                let dEnd := add(dest, length)
                                                // Remember the last 32 bytes of source
                                                // This needs to be done here and not after the loop
                                                // because we may have overwritten the last bytes in
                                                // source already due to overlap.
                                                let last := mload(sEnd)
                                                // Copy whole words front to back
                                                // Note: the first check is always true,
                                                // this could have been a do-while loop.
                                                for {
                                                } lt(source, sEnd) {
                                                } {
                                                    mstore(dest, mload(source))
                                                    source := add(source, 32)
                                                    dest := add(dest, 32)
                                                }
                                                // Write the last 32 bytes
                                                mstore(dEnd, last)
                                            }
                                        } else {
                                            assembly {
                                                // We subtract 32 from `sEnd` and `dEnd` because those
                                                // are the starting points when copying a word at the end.
                                                length := sub(length, 32)
                                                let sEnd := add(source, length)
                                                let dEnd := add(dest, length)
                                                // Remember the first 32 bytes of source
                                                // This needs to be done here and not after the loop
                                                // because we may have overwritten the first bytes in
                                                // source already due to overlap.
                                                let first := mload(source)
                                                // Copy whole words back to front
                                                // We use a signed comparisson here to allow dEnd to become
                                                // negative (happens when source and dest < 32). Valid
                                                // addresses in local memory will never be larger than
                                                // 2**255, so they can be safely re-interpreted as signed.
                                                // Note: the first check is always true,
                                                // this could have been a do-while loop.
                                                for {
                                                } slt(dest, dEnd) {
                                                } {
                                                    mstore(dEnd, mload(sEnd))
                                                    sEnd := sub(sEnd, 32)
                                                    dEnd := sub(dEnd, 32)
                                                }
                                                // Write the first 32 bytes
                                                mstore(dest, first)
                                            }
                                        }
                                    }
                                }
                                /// @dev Returns a slices from a byte array.
                                /// @param b The byte array to take a slice from.
                                /// @param from The starting index for the slice (inclusive).
                                /// @param to The final index for the slice (exclusive).
                                /// @return result The slice containing bytes at indices [from, to)
                                function slice(bytes memory b, uint256 from, uint256 to) internal pure returns (bytes memory result) {
                                    // Ensure that the from and to positions are valid positions for a slice within
                                    // the byte array that is being used.
                                    if (from > to) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.FromLessThanOrEqualsToRequired,
                                                from,
                                                to
                                            )
                                        );
                                    }
                                    if (to > b.length) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.ToLessThanOrEqualsLengthRequired,
                                                to,
                                                b.length
                                            )
                                        );
                                    }
                                    // Create a new bytes structure and copy contents
                                    result = new bytes(to - from);
                                    memCopy(result.contentAddress(), b.contentAddress() + from, result.length);
                                    return result;
                                }
                                /// @dev Returns a slice from a byte array without preserving the input.
                                ///      When `from == 0`, the original array will match the slice.
                                ///      In other cases its state will be corrupted.
                                /// @param b The byte array to take a slice from. Will be destroyed in the process.
                                /// @param from The starting index for the slice (inclusive).
                                /// @param to The final index for the slice (exclusive).
                                /// @return result The slice containing bytes at indices [from, to)
                                function sliceDestructive(bytes memory b, uint256 from, uint256 to) internal pure returns (bytes memory result) {
                                    // Ensure that the from and to positions are valid positions for a slice within
                                    // the byte array that is being used.
                                    if (from > to) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.FromLessThanOrEqualsToRequired,
                                                from,
                                                to
                                            )
                                        );
                                    }
                                    if (to > b.length) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.ToLessThanOrEqualsLengthRequired,
                                                to,
                                                b.length
                                            )
                                        );
                                    }
                                    // Create a new bytes structure around [from, to) in-place.
                                    assembly {
                                        result := add(b, from)
                                        mstore(result, sub(to, from))
                                    }
                                    return result;
                                }
                                /// @dev Pops the last byte off of a byte array by modifying its length.
                                /// @param b Byte array that will be modified.
                                /// @return result The byte that was popped off.
                                function popLastByte(bytes memory b) internal pure returns (bytes1 result) {
                                    if (b.length == 0) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanZeroRequired,
                                                b.length,
                                                0
                                            )
                                        );
                                    }
                                    // Store last byte.
                                    result = b[b.length - 1];
                                    assembly {
                                        // Decrement length of byte array.
                                        let newLen := sub(mload(b), 1)
                                        mstore(b, newLen)
                                    }
                                    return result;
                                }
                                /// @dev Tests equality of two byte arrays.
                                /// @param lhs First byte array to compare.
                                /// @param rhs Second byte array to compare.
                                /// @return equal True if arrays are the same. False otherwise.
                                function equals(bytes memory lhs, bytes memory rhs) internal pure returns (bool equal) {
                                    // Keccak gas cost is 30 + numWords * 6. This is a cheap way to compare.
                                    // We early exit on unequal lengths, but keccak would also correctly
                                    // handle this.
                                    return lhs.length == rhs.length && keccak256(lhs) == keccak256(rhs);
                                }
                                /// @dev Reads an address from a position in a byte array.
                                /// @param b Byte array containing an address.
                                /// @param index Index in byte array of address.
                                /// @return result address from byte array.
                                function readAddress(bytes memory b, uint256 index) internal pure returns (address result) {
                                    if (b.length < index + 20) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsTwentyRequired,
                                                b.length,
                                                index + 20 // 20 is length of address
                                            )
                                        );
                                    }
                                    // Add offset to index:
                                    // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
                                    // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
                                    index += 20;
                                    // Read address from array memory
                                    assembly {
                                        // 1. Add index to address of bytes array
                                        // 2. Load 32-byte word from memory
                                        // 3. Apply 20-byte mask to obtain address
                                        result := and(mload(add(b, index)), 0xffffffffffffffffffffffffffffffffffffffff)
                                    }
                                    return result;
                                }
                                /// @dev Writes an address into a specific position in a byte array.
                                /// @param b Byte array to insert address into.
                                /// @param index Index in byte array of address.
                                /// @param input Address to put into byte array.
                                function writeAddress(bytes memory b, uint256 index, address input) internal pure {
                                    if (b.length < index + 20) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsTwentyRequired,
                                                b.length,
                                                index + 20 // 20 is length of address
                                            )
                                        );
                                    }
                                    // Add offset to index:
                                    // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
                                    // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
                                    index += 20;
                                    // Store address into array memory
                                    assembly {
                                        // The address occupies 20 bytes and mstore stores 32 bytes.
                                        // First fetch the 32-byte word where we'll be storing the address, then
                                        // apply a mask so we have only the bytes in the word that the address will not occupy.
                                        // Then combine these bytes with the address and store the 32 bytes back to memory with mstore.
                                        // 1. Add index to address of bytes array
                                        // 2. Load 32-byte word from memory
                                        // 3. Apply 12-byte mask to obtain extra bytes occupying word of memory where we'll store the address
                                        let neighbors := and(
                                            mload(add(b, index)),
                                            0xffffffffffffffffffffffff0000000000000000000000000000000000000000
                                        )
                                        // Make sure input address is clean.
                                        // (Solidity does not guarantee this)
                                        input := and(input, 0xffffffffffffffffffffffffffffffffffffffff)
                                        // Store the neighbors and address into memory
                                        mstore(add(b, index), xor(input, neighbors))
                                    }
                                }
                                /// @dev Reads a bytes32 value from a position in a byte array.
                                /// @param b Byte array containing a bytes32 value.
                                /// @param index Index in byte array of bytes32 value.
                                /// @return result bytes32 value from byte array.
                                function readBytes32(bytes memory b, uint256 index) internal pure returns (bytes32 result) {
                                    if (b.length < index + 32) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsThirtyTwoRequired,
                                                b.length,
                                                index + 32
                                            )
                                        );
                                    }
                                    // Arrays are prefixed by a 256 bit length parameter
                                    index += 32;
                                    // Read the bytes32 from array memory
                                    assembly {
                                        result := mload(add(b, index))
                                    }
                                    return result;
                                }
                                /// @dev Writes a bytes32 into a specific position in a byte array.
                                /// @param b Byte array to insert <input> into.
                                /// @param index Index in byte array of <input>.
                                /// @param input bytes32 to put into byte array.
                                function writeBytes32(bytes memory b, uint256 index, bytes32 input) internal pure {
                                    if (b.length < index + 32) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsThirtyTwoRequired,
                                                b.length,
                                                index + 32
                                            )
                                        );
                                    }
                                    // Arrays are prefixed by a 256 bit length parameter
                                    index += 32;
                                    // Read the bytes32 from array memory
                                    assembly {
                                        mstore(add(b, index), input)
                                    }
                                }
                                /// @dev Reads a uint256 value from a position in a byte array.
                                /// @param b Byte array containing a uint256 value.
                                /// @param index Index in byte array of uint256 value.
                                /// @return result uint256 value from byte array.
                                function readUint256(bytes memory b, uint256 index) internal pure returns (uint256 result) {
                                    result = uint256(readBytes32(b, index));
                                    return result;
                                }
                                /// @dev Writes a uint256 into a specific position in a byte array.
                                /// @param b Byte array to insert <input> into.
                                /// @param index Index in byte array of <input>.
                                /// @param input uint256 to put into byte array.
                                function writeUint256(bytes memory b, uint256 index, uint256 input) internal pure {
                                    writeBytes32(b, index, bytes32(input));
                                }
                                /// @dev Reads an unpadded bytes4 value from a position in a byte array.
                                /// @param b Byte array containing a bytes4 value.
                                /// @param index Index in byte array of bytes4 value.
                                /// @return result bytes4 value from byte array.
                                function readBytes4(bytes memory b, uint256 index) internal pure returns (bytes4 result) {
                                    if (b.length < index + 4) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsFourRequired,
                                                b.length,
                                                index + 4
                                            )
                                        );
                                    }
                                    // Arrays are prefixed by a 32 byte length field
                                    index += 32;
                                    // Read the bytes4 from array memory
                                    assembly {
                                        result := mload(add(b, index))
                                        // Solidity does not require us to clean the trailing bytes.
                                        // We do it anyway
                                        result := and(result, 0xFFFFFFFF00000000000000000000000000000000000000000000000000000000)
                                    }
                                    return result;
                                }
                                /// @dev Writes a new length to a byte array.
                                ///      Decreasing length will lead to removing the corresponding lower order bytes from the byte array.
                                ///      Increasing length may lead to appending adjacent in-memory bytes to the end of the byte array.
                                /// @param b Bytes array to write new length to.
                                /// @param length New length of byte array.
                                function writeLength(bytes memory b, uint256 length) internal pure {
                                    assembly {
                                        mstore(b, length)
                                    }
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibBytesRichErrorsV06 {
                                enum InvalidByteOperationErrorCodes {
                                    FromLessThanOrEqualsToRequired,
                                    ToLessThanOrEqualsLengthRequired,
                                    LengthGreaterThanZeroRequired,
                                    LengthGreaterThanOrEqualsFourRequired,
                                    LengthGreaterThanOrEqualsTwentyRequired,
                                    LengthGreaterThanOrEqualsThirtyTwoRequired,
                                    LengthGreaterThanOrEqualsNestedBytesLengthRequired,
                                    DestinationLengthGreaterThanOrEqualSourceLengthRequired
                                }
                                // bytes4(keccak256("InvalidByteOperationError(uint8,uint256,uint256)"))
                                bytes4 internal constant INVALID_BYTE_OPERATION_ERROR_SELECTOR = 0x28006595;
                                function InvalidByteOperationError(
                                    InvalidByteOperationErrorCodes errorCode,
                                    uint256 offset,
                                    uint256 required
                                ) internal pure returns (bytes memory) {
                                    return abi.encodeWithSelector(INVALID_BYTE_OPERATION_ERROR_SELECTOR, errorCode, offset, required);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./errors/LibRichErrorsV06.sol";
                            import "./errors/LibSafeMathRichErrorsV06.sol";
                            library LibSafeMathV06 {
                                function safeMul(uint256 a, uint256 b) internal pure returns (uint256) {
                                    if (a == 0) {
                                        return 0;
                                    }
                                    uint256 c = a * b;
                                    if (c / a != b) {
                                        LibRichErrorsV06.rrevert(
                                            LibSafeMathRichErrorsV06.Uint256BinOpError(
                                                LibSafeMathRichErrorsV06.BinOpErrorCodes.MULTIPLICATION_OVERFLOW,
                                                a,
                                                b
                                            )
                                        );
                                    }
                                    return c;
                                }
                                function safeDiv(uint256 a, uint256 b) internal pure returns (uint256) {
                                    if (b == 0) {
                                        LibRichErrorsV06.rrevert(
                                            LibSafeMathRichErrorsV06.Uint256BinOpError(
                                                LibSafeMathRichErrorsV06.BinOpErrorCodes.DIVISION_BY_ZERO,
                                                a,
                                                b
                                            )
                                        );
                                    }
                                    uint256 c = a / b;
                                    return c;
                                }
                                function safeSub(uint256 a, uint256 b) internal pure returns (uint256) {
                                    if (b > a) {
                                        LibRichErrorsV06.rrevert(
                                            LibSafeMathRichErrorsV06.Uint256BinOpError(
                                                LibSafeMathRichErrorsV06.BinOpErrorCodes.SUBTRACTION_UNDERFLOW,
                                                a,
                                                b
                                            )
                                        );
                                    }
                                    return a - b;
                                }
                                function safeAdd(uint256 a, uint256 b) internal pure returns (uint256) {
                                    uint256 c = a + b;
                                    if (c < a) {
                                        LibRichErrorsV06.rrevert(
                                            LibSafeMathRichErrorsV06.Uint256BinOpError(
                                                LibSafeMathRichErrorsV06.BinOpErrorCodes.ADDITION_OVERFLOW,
                                                a,
                                                b
                                            )
                                        );
                                    }
                                    return c;
                                }
                                function max256(uint256 a, uint256 b) internal pure returns (uint256) {
                                    return a >= b ? a : b;
                                }
                                function min256(uint256 a, uint256 b) internal pure returns (uint256) {
                                    return a < b ? a : b;
                                }
                                function safeMul128(uint128 a, uint128 b) internal pure returns (uint128) {
                                    if (a == 0) {
                                        return 0;
                                    }
                                    uint128 c = a * b;
                                    if (c / a != b) {
                                        LibRichErrorsV06.rrevert(
                                            LibSafeMathRichErrorsV06.Uint256BinOpError(
                                                LibSafeMathRichErrorsV06.BinOpErrorCodes.MULTIPLICATION_OVERFLOW,
                                                a,
                                                b
                                            )
                                        );
                                    }
                                    return c;
                                }
                                function safeDiv128(uint128 a, uint128 b) internal pure returns (uint128) {
                                    if (b == 0) {
                                        LibRichErrorsV06.rrevert(
                                            LibSafeMathRichErrorsV06.Uint256BinOpError(
                                                LibSafeMathRichErrorsV06.BinOpErrorCodes.DIVISION_BY_ZERO,
                                                a,
                                                b
                                            )
                                        );
                                    }
                                    uint128 c = a / b;
                                    return c;
                                }
                                function safeSub128(uint128 a, uint128 b) internal pure returns (uint128) {
                                    if (b > a) {
                                        LibRichErrorsV06.rrevert(
                                            LibSafeMathRichErrorsV06.Uint256BinOpError(
                                                LibSafeMathRichErrorsV06.BinOpErrorCodes.SUBTRACTION_UNDERFLOW,
                                                a,
                                                b
                                            )
                                        );
                                    }
                                    return a - b;
                                }
                                function safeAdd128(uint128 a, uint128 b) internal pure returns (uint128) {
                                    uint128 c = a + b;
                                    if (c < a) {
                                        LibRichErrorsV06.rrevert(
                                            LibSafeMathRichErrorsV06.Uint256BinOpError(
                                                LibSafeMathRichErrorsV06.BinOpErrorCodes.ADDITION_OVERFLOW,
                                                a,
                                                b
                                            )
                                        );
                                    }
                                    return c;
                                }
                                function max128(uint128 a, uint128 b) internal pure returns (uint128) {
                                    return a >= b ? a : b;
                                }
                                function min128(uint128 a, uint128 b) internal pure returns (uint128) {
                                    return a < b ? a : b;
                                }
                                function safeDowncastToUint128(uint256 a) internal pure returns (uint128) {
                                    if (a > type(uint128).max) {
                                        LibRichErrorsV06.rrevert(
                                            LibSafeMathRichErrorsV06.Uint256DowncastError(
                                                LibSafeMathRichErrorsV06.DowncastErrorCodes.VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT128,
                                                a
                                            )
                                        );
                                    }
                                    return uint128(a);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibSafeMathRichErrorsV06 {
                                // bytes4(keccak256("Uint256BinOpError(uint8,uint256,uint256)"))
                                bytes4 internal constant UINT256_BINOP_ERROR_SELECTOR = 0xe946c1bb;
                                // bytes4(keccak256("Uint256DowncastError(uint8,uint256)"))
                                bytes4 internal constant UINT256_DOWNCAST_ERROR_SELECTOR = 0xc996af7b;
                                enum BinOpErrorCodes {
                                    ADDITION_OVERFLOW,
                                    MULTIPLICATION_OVERFLOW,
                                    SUBTRACTION_UNDERFLOW,
                                    DIVISION_BY_ZERO
                                }
                                enum DowncastErrorCodes {
                                    VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT32,
                                    VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT64,
                                    VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT96,
                                    VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT128
                                }
                                function Uint256BinOpError(BinOpErrorCodes errorCode, uint256 a, uint256 b) internal pure returns (bytes memory) {
                                    return abi.encodeWithSelector(UINT256_BINOP_ERROR_SELECTOR, errorCode, a, b);
                                }
                                function Uint256DowncastError(DowncastErrorCodes errorCode, uint256 a) internal pure returns (bytes memory) {
                                    return abi.encodeWithSelector(UINT256_DOWNCAST_ERROR_SELECTOR, errorCode, a);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2019 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./LibSafeMathV06.sol";
                            import "./errors/LibRichErrorsV06.sol";
                            import "./errors/LibMathRichErrorsV06.sol";
                            library LibMathV06 {
                                using LibSafeMathV06 for uint256;
                                /// @dev Calculates partial value given a numerator and denominator rounded down.
                                ///      Reverts if rounding error is >= 0.1%
                                /// @param numerator Numerator.
                                /// @param denominator Denominator.
                                /// @param target Value to calculate partial of.
                                /// @return partialAmount Partial value of target rounded down.
                                function safeGetPartialAmountFloor(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                ) internal pure returns (uint256 partialAmount) {
                                    if (isRoundingErrorFloor(numerator, denominator, target)) {
                                        LibRichErrorsV06.rrevert(LibMathRichErrorsV06.RoundingError(numerator, denominator, target));
                                    }
                                    partialAmount = numerator.safeMul(target).safeDiv(denominator);
                                    return partialAmount;
                                }
                                /// @dev Calculates partial value given a numerator and denominator rounded down.
                                ///      Reverts if rounding error is >= 0.1%
                                /// @param numerator Numerator.
                                /// @param denominator Denominator.
                                /// @param target Value to calculate partial of.
                                /// @return partialAmount Partial value of target rounded up.
                                function safeGetPartialAmountCeil(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                ) internal pure returns (uint256 partialAmount) {
                                    if (isRoundingErrorCeil(numerator, denominator, target)) {
                                        LibRichErrorsV06.rrevert(LibMathRichErrorsV06.RoundingError(numerator, denominator, target));
                                    }
                                    // safeDiv computes `floor(a / b)`. We use the identity (a, b integer):
                                    //       ceil(a / b) = floor((a + b - 1) / b)
                                    // To implement `ceil(a / b)` using safeDiv.
                                    partialAmount = numerator.safeMul(target).safeAdd(denominator.safeSub(1)).safeDiv(denominator);
                                    return partialAmount;
                                }
                                /// @dev Calculates partial value given a numerator and denominator rounded down.
                                /// @param numerator Numerator.
                                /// @param denominator Denominator.
                                /// @param target Value to calculate partial of.
                                /// @return partialAmount Partial value of target rounded down.
                                function getPartialAmountFloor(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                ) internal pure returns (uint256 partialAmount) {
                                    partialAmount = numerator.safeMul(target).safeDiv(denominator);
                                    return partialAmount;
                                }
                                /// @dev Calculates partial value given a numerator and denominator rounded down.
                                /// @param numerator Numerator.
                                /// @param denominator Denominator.
                                /// @param target Value to calculate partial of.
                                /// @return partialAmount Partial value of target rounded up.
                                function getPartialAmountCeil(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                ) internal pure returns (uint256 partialAmount) {
                                    // safeDiv computes `floor(a / b)`. We use the identity (a, b integer):
                                    //       ceil(a / b) = floor((a + b - 1) / b)
                                    // To implement `ceil(a / b)` using safeDiv.
                                    partialAmount = numerator.safeMul(target).safeAdd(denominator.safeSub(1)).safeDiv(denominator);
                                    return partialAmount;
                                }
                                /// @dev Checks if rounding error >= 0.1% when rounding down.
                                /// @param numerator Numerator.
                                /// @param denominator Denominator.
                                /// @param target Value to multiply with numerator/denominator.
                                /// @return isError Rounding error is present.
                                function isRoundingErrorFloor(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                ) internal pure returns (bool isError) {
                                    if (denominator == 0) {
                                        LibRichErrorsV06.rrevert(LibMathRichErrorsV06.DivisionByZeroError());
                                    }
                                    // The absolute rounding error is the difference between the rounded
                                    // value and the ideal value. The relative rounding error is the
                                    // absolute rounding error divided by the absolute value of the
                                    // ideal value. This is undefined when the ideal value is zero.
                                    //
                                    // The ideal value is `numerator * target / denominator`.
                                    // Let's call `numerator * target % denominator` the remainder.
                                    // The absolute error is `remainder / denominator`.
                                    //
                                    // When the ideal value is zero, we require the absolute error to
                                    // be zero. Fortunately, this is always the case. The ideal value is
                                    // zero iff `numerator == 0` and/or `target == 0`. In this case the
                                    // remainder and absolute error are also zero.
                                    if (target == 0 || numerator == 0) {
                                        return false;
                                    }
                                    // Otherwise, we want the relative rounding error to be strictly
                                    // less than 0.1%.
                                    // The relative error is `remainder / (numerator * target)`.
                                    // We want the relative error less than 1 / 1000:
                                    //        remainder / (numerator * denominator)  <  1 / 1000
                                    // or equivalently:
                                    //        1000 * remainder  <  numerator * target
                                    // so we have a rounding error iff:
                                    //        1000 * remainder  >=  numerator * target
                                    uint256 remainder = mulmod(target, numerator, denominator);
                                    isError = remainder.safeMul(1000) >= numerator.safeMul(target);
                                    return isError;
                                }
                                /// @dev Checks if rounding error >= 0.1% when rounding up.
                                /// @param numerator Numerator.
                                /// @param denominator Denominator.
                                /// @param target Value to multiply with numerator/denominator.
                                /// @return isError Rounding error is present.
                                function isRoundingErrorCeil(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                ) internal pure returns (bool isError) {
                                    if (denominator == 0) {
                                        LibRichErrorsV06.rrevert(LibMathRichErrorsV06.DivisionByZeroError());
                                    }
                                    // See the comments in `isRoundingError`.
                                    if (target == 0 || numerator == 0) {
                                        // When either is zero, the ideal value and rounded value are zero
                                        // and there is no rounding error. (Although the relative error
                                        // is undefined.)
                                        return false;
                                    }
                                    // Compute remainder as before
                                    uint256 remainder = mulmod(target, numerator, denominator);
                                    remainder = denominator.safeSub(remainder) % denominator;
                                    isError = remainder.safeMul(1000) >= numerator.safeMul(target);
                                    return isError;
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibMathRichErrorsV06 {
                                // bytes4(keccak256("DivisionByZeroError()"))
                                bytes internal constant DIVISION_BY_ZERO_ERROR = hex"a791837c";
                                // bytes4(keccak256("RoundingError(uint256,uint256,uint256)"))
                                bytes4 internal constant ROUNDING_ERROR_SELECTOR = 0x339f3de2;
                                function DivisionByZeroError() internal pure returns (bytes memory) {
                                    return DIVISION_BY_ZERO_ERROR;
                                }
                                function RoundingError(
                                    uint256 numerator,
                                    uint256 denominator,
                                    uint256 target
                                ) internal pure returns (bytes memory) {
                                    return abi.encodeWithSelector(ROUNDING_ERROR_SELECTOR, numerator, denominator, target);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibTransformERC20RichErrors {
                                function InsufficientEthAttachedError(uint256 ethAttached, uint256 ethNeeded) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("InsufficientEthAttachedError(uint256,uint256)")),
                                            ethAttached,
                                            ethNeeded
                                        );
                                }
                                function IncompleteTransformERC20Error(
                                    address outputToken,
                                    uint256 outputTokenAmount,
                                    uint256 minOutputTokenAmount
                                ) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("IncompleteTransformERC20Error(address,uint256,uint256)")),
                                            outputToken,
                                            outputTokenAmount,
                                            minOutputTokenAmount
                                        );
                                }
                                function NegativeTransformERC20OutputError(
                                    address outputToken,
                                    uint256 outputTokenLostAmount
                                ) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("NegativeTransformERC20OutputError(address,uint256)")),
                                            outputToken,
                                            outputTokenLostAmount
                                        );
                                }
                                function TransformerFailedError(
                                    address transformer,
                                    bytes memory transformerData,
                                    bytes memory resultData
                                ) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("TransformerFailedError(address,bytes,bytes)")),
                                            transformer,
                                            transformerData,
                                            resultData
                                        );
                                }
                                // Common Transformer errors ///////////////////////////////////////////////
                                function OnlyCallableByDeployerError(address caller, address deployer) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(bytes4(keccak256("OnlyCallableByDeployerError(address,address)")), caller, deployer);
                                }
                                function InvalidExecutionContextError(
                                    address actualContext,
                                    address expectedContext
                                ) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("InvalidExecutionContextError(address,address)")),
                                            actualContext,
                                            expectedContext
                                        );
                                }
                                enum InvalidTransformDataErrorCode {
                                    INVALID_TOKENS,
                                    INVALID_ARRAY_LENGTH
                                }
                                function InvalidTransformDataError(
                                    InvalidTransformDataErrorCode errorCode,
                                    bytes memory transformData
                                ) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("InvalidTransformDataError(uint8,bytes)")),
                                            errorCode,
                                            transformData
                                        );
                                }
                                // FillQuoteTransformer errors /////////////////////////////////////////////
                                function IncompleteFillSellQuoteError(
                                    address sellToken,
                                    uint256 soldAmount,
                                    uint256 sellAmount
                                ) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("IncompleteFillSellQuoteError(address,uint256,uint256)")),
                                            sellToken,
                                            soldAmount,
                                            sellAmount
                                        );
                                }
                                function IncompleteFillBuyQuoteError(
                                    address buyToken,
                                    uint256 boughtAmount,
                                    uint256 buyAmount
                                ) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("IncompleteFillBuyQuoteError(address,uint256,uint256)")),
                                            buyToken,
                                            boughtAmount,
                                            buyAmount
                                        );
                                }
                                function InsufficientTakerTokenError(
                                    uint256 tokenBalance,
                                    uint256 tokensNeeded
                                ) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("InsufficientTakerTokenError(uint256,uint256)")),
                                            tokenBalance,
                                            tokensNeeded
                                        );
                                }
                                function InsufficientProtocolFeeError(uint256 ethBalance, uint256 ethNeeded) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("InsufficientProtocolFeeError(uint256,uint256)")),
                                            ethBalance,
                                            ethNeeded
                                        );
                                }
                                function InvalidERC20AssetDataError(bytes memory assetData) internal pure returns (bytes memory) {
                                    return abi.encodeWithSelector(bytes4(keccak256("InvalidERC20AssetDataError(bytes)")), assetData);
                                }
                                function InvalidTakerFeeTokenError(address token) internal pure returns (bytes memory) {
                                    return abi.encodeWithSelector(bytes4(keccak256("InvalidTakerFeeTokenError(address)")), token);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "../libs/LibSignature.sol";
                            import "../libs/LibNativeOrder.sol";
                            import "./INativeOrdersEvents.sol";
                            /// @dev Feature for interacting with limit orders.
                            interface INativeOrdersFeature is INativeOrdersEvents {
                                /// @dev Transfers protocol fees from the `FeeCollector` pools into
                                ///      the staking contract.
                                /// @param poolIds Staking pool IDs
                                function transferProtocolFeesForPools(bytes32[] calldata poolIds) external;
                                /// @dev Fill a limit order. The taker and sender will be the caller.
                                /// @param order The limit order. ETH protocol fees can be
                                ///      attached to this call. Any unspent ETH will be refunded to
                                ///      the caller.
                                /// @param signature The order signature.
                                /// @param takerTokenFillAmount Maximum taker token amount to fill this order with.
                                /// @return takerTokenFilledAmount How much maker token was filled.
                                /// @return makerTokenFilledAmount How much maker token was filled.
                                function fillLimitOrder(
                                    LibNativeOrder.LimitOrder calldata order,
                                    LibSignature.Signature calldata signature,
                                    uint128 takerTokenFillAmount
                                ) external payable returns (uint128 takerTokenFilledAmount, uint128 makerTokenFilledAmount);
                                /// @dev Fill an RFQ order for up to `takerTokenFillAmount` taker tokens.
                                ///      The taker will be the caller.
                                /// @param order The RFQ order.
                                /// @param signature The order signature.
                                /// @param takerTokenFillAmount Maximum taker token amount to fill this order with.
                                /// @return takerTokenFilledAmount How much maker token was filled.
                                /// @return makerTokenFilledAmount How much maker token was filled.
                                function fillRfqOrder(
                                    LibNativeOrder.RfqOrder calldata order,
                                    LibSignature.Signature calldata signature,
                                    uint128 takerTokenFillAmount
                                ) external returns (uint128 takerTokenFilledAmount, uint128 makerTokenFilledAmount);
                                /// @dev Fill an RFQ order for exactly `takerTokenFillAmount` taker tokens.
                                ///      The taker will be the caller. ETH protocol fees can be
                                ///      attached to this call. Any unspent ETH will be refunded to
                                ///      the caller.
                                /// @param order The limit order.
                                /// @param signature The order signature.
                                /// @param takerTokenFillAmount How much taker token to fill this order with.
                                /// @return makerTokenFilledAmount How much maker token was filled.
                                function fillOrKillLimitOrder(
                                    LibNativeOrder.LimitOrder calldata order,
                                    LibSignature.Signature calldata signature,
                                    uint128 takerTokenFillAmount
                                ) external payable returns (uint128 makerTokenFilledAmount);
                                /// @dev Fill an RFQ order for exactly `takerTokenFillAmount` taker tokens.
                                ///      The taker will be the caller.
                                /// @param order The RFQ order.
                                /// @param signature The order signature.
                                /// @param takerTokenFillAmount How much taker token to fill this order with.
                                /// @return makerTokenFilledAmount How much maker token was filled.
                                function fillOrKillRfqOrder(
                                    LibNativeOrder.RfqOrder calldata order,
                                    LibSignature.Signature calldata signature,
                                    uint128 takerTokenFillAmount
                                ) external returns (uint128 makerTokenFilledAmount);
                                /// @dev Fill a limit order. Internal variant. ETH protocol fees can be
                                ///      attached to this call. Any unspent ETH will be refunded to
                                ///      `msg.sender` (not `sender`).
                                /// @param order The limit order.
                                /// @param signature The order signature.
                                /// @param takerTokenFillAmount Maximum taker token to fill this order with.
                                /// @param taker The order taker.
                                /// @param sender The order sender.
                                /// @return takerTokenFilledAmount How much maker token was filled.
                                /// @return makerTokenFilledAmount How much maker token was filled.
                                function _fillLimitOrder(
                                    LibNativeOrder.LimitOrder calldata order,
                                    LibSignature.Signature calldata signature,
                                    uint128 takerTokenFillAmount,
                                    address taker,
                                    address sender
                                ) external payable returns (uint128 takerTokenFilledAmount, uint128 makerTokenFilledAmount);
                                /// @dev Fill an RFQ order. Internal variant.
                                /// @param order The RFQ order.
                                /// @param signature The order signature.
                                /// @param takerTokenFillAmount Maximum taker token to fill this order with.
                                /// @param taker The order taker.
                                /// @param useSelfBalance Whether to use the ExchangeProxy's transient
                                ///        balance of taker tokens to fill the order.
                                /// @param recipient The recipient of the maker tokens.
                                /// @return takerTokenFilledAmount How much maker token was filled.
                                /// @return makerTokenFilledAmount How much maker token was filled.
                                function _fillRfqOrder(
                                    LibNativeOrder.RfqOrder calldata order,
                                    LibSignature.Signature calldata signature,
                                    uint128 takerTokenFillAmount,
                                    address taker,
                                    bool useSelfBalance,
                                    address recipient
                                ) external returns (uint128 takerTokenFilledAmount, uint128 makerTokenFilledAmount);
                                /// @dev Cancel a single limit order. The caller must be the maker or a valid order signer.
                                ///      Silently succeeds if the order has already been cancelled.
                                /// @param order The limit order.
                                function cancelLimitOrder(LibNativeOrder.LimitOrder calldata order) external;
                                /// @dev Cancel a single RFQ order. The caller must be the maker or a valid order signer.
                                ///      Silently succeeds if the order has already been cancelled.
                                /// @param order The RFQ order.
                                function cancelRfqOrder(LibNativeOrder.RfqOrder calldata order) external;
                                /// @dev Mark what tx.origin addresses are allowed to fill an order that
                                ///      specifies the message sender as its txOrigin.
                                /// @param origins An array of origin addresses to update.
                                /// @param allowed True to register, false to unregister.
                                function registerAllowedRfqOrigins(address[] memory origins, bool allowed) external;
                                /// @dev Cancel multiple limit orders. The caller must be the maker or a valid order signer.
                                ///      Silently succeeds if the order has already been cancelled.
                                /// @param orders The limit orders.
                                function batchCancelLimitOrders(LibNativeOrder.LimitOrder[] calldata orders) external;
                                /// @dev Cancel multiple RFQ orders. The caller must be the maker or a valid order signer.
                                ///      Silently succeeds if the order has already been cancelled.
                                /// @param orders The RFQ orders.
                                function batchCancelRfqOrders(LibNativeOrder.RfqOrder[] calldata orders) external;
                                /// @dev Cancel all limit orders for a given maker and pair with a salt less
                                ///      than the value provided. The caller must be the maker. Subsequent
                                ///      calls to this function with the same caller and pair require the
                                ///      new salt to be >= the old salt.
                                /// @param makerToken The maker token.
                                /// @param takerToken The taker token.
                                /// @param minValidSalt The new minimum valid salt.
                                function cancelPairLimitOrders(IERC20Token makerToken, IERC20Token takerToken, uint256 minValidSalt) external;
                                /// @dev Cancel all limit orders for a given maker and pair with a salt less
                                ///      than the value provided. The caller must be a signer registered to the maker.
                                ///      Subsequent calls to this function with the same maker and pair require the
                                ///      new salt to be >= the old salt.
                                /// @param maker The maker for which to cancel.
                                /// @param makerToken The maker token.
                                /// @param takerToken The taker token.
                                /// @param minValidSalt The new minimum valid salt.
                                function cancelPairLimitOrdersWithSigner(
                                    address maker,
                                    IERC20Token makerToken,
                                    IERC20Token takerToken,
                                    uint256 minValidSalt
                                ) external;
                                /// @dev Cancel all limit orders for a given maker and pairs with salts less
                                ///      than the values provided. The caller must be the maker. Subsequent
                                ///      calls to this function with the same caller and pair require the
                                ///      new salt to be >= the old salt.
                                /// @param makerTokens The maker tokens.
                                /// @param takerTokens The taker tokens.
                                /// @param minValidSalts The new minimum valid salts.
                                function batchCancelPairLimitOrders(
                                    IERC20Token[] calldata makerTokens,
                                    IERC20Token[] calldata takerTokens,
                                    uint256[] calldata minValidSalts
                                ) external;
                                /// @dev Cancel all limit orders for a given maker and pairs with salts less
                                ///      than the values provided. The caller must be a signer registered to the maker.
                                ///      Subsequent calls to this function with the same maker and pair require the
                                ///      new salt to be >= the old salt.
                                /// @param maker The maker for which to cancel.
                                /// @param makerTokens The maker tokens.
                                /// @param takerTokens The taker tokens.
                                /// @param minValidSalts The new minimum valid salts.
                                function batchCancelPairLimitOrdersWithSigner(
                                    address maker,
                                    IERC20Token[] memory makerTokens,
                                    IERC20Token[] memory takerTokens,
                                    uint256[] memory minValidSalts
                                ) external;
                                /// @dev Cancel all RFQ orders for a given maker and pair with a salt less
                                ///      than the value provided. The caller must be the maker. Subsequent
                                ///      calls to this function with the same caller and pair require the
                                ///      new salt to be >= the old salt.
                                /// @param makerToken The maker token.
                                /// @param takerToken The taker token.
                                /// @param minValidSalt The new minimum valid salt.
                                function cancelPairRfqOrders(IERC20Token makerToken, IERC20Token takerToken, uint256 minValidSalt) external;
                                /// @dev Cancel all RFQ orders for a given maker and pair with a salt less
                                ///      than the value provided. The caller must be a signer registered to the maker.
                                ///      Subsequent calls to this function with the same maker and pair require the
                                ///      new salt to be >= the old salt.
                                /// @param maker The maker for which to cancel.
                                /// @param makerToken The maker token.
                                /// @param takerToken The taker token.
                                /// @param minValidSalt The new minimum valid salt.
                                function cancelPairRfqOrdersWithSigner(
                                    address maker,
                                    IERC20Token makerToken,
                                    IERC20Token takerToken,
                                    uint256 minValidSalt
                                ) external;
                                /// @dev Cancel all RFQ orders for a given maker and pairs with salts less
                                ///      than the values provided. The caller must be the maker. Subsequent
                                ///      calls to this function with the same caller and pair require the
                                ///      new salt to be >= the old salt.
                                /// @param makerTokens The maker tokens.
                                /// @param takerTokens The taker tokens.
                                /// @param minValidSalts The new minimum valid salts.
                                function batchCancelPairRfqOrders(
                                    IERC20Token[] calldata makerTokens,
                                    IERC20Token[] calldata takerTokens,
                                    uint256[] calldata minValidSalts
                                ) external;
                                /// @dev Cancel all RFQ orders for a given maker and pairs with salts less
                                ///      than the values provided. The caller must be a signer registered to the maker.
                                ///      Subsequent calls to this function with the same maker and pair require the
                                ///      new salt to be >= the old salt.
                                /// @param maker The maker for which to cancel.
                                /// @param makerTokens The maker tokens.
                                /// @param takerTokens The taker tokens.
                                /// @param minValidSalts The new minimum valid salts.
                                function batchCancelPairRfqOrdersWithSigner(
                                    address maker,
                                    IERC20Token[] memory makerTokens,
                                    IERC20Token[] memory takerTokens,
                                    uint256[] memory minValidSalts
                                ) external;
                                /// @dev Get the order info for a limit order.
                                /// @param order The limit order.
                                /// @return orderInfo Info about the order.
                                function getLimitOrderInfo(
                                    LibNativeOrder.LimitOrder calldata order
                                ) external view returns (LibNativeOrder.OrderInfo memory orderInfo);
                                /// @dev Get the order info for an RFQ order.
                                /// @param order The RFQ order.
                                /// @return orderInfo Info about the order.
                                function getRfqOrderInfo(
                                    LibNativeOrder.RfqOrder calldata order
                                ) external view returns (LibNativeOrder.OrderInfo memory orderInfo);
                                /// @dev Get the canonical hash of a limit order.
                                /// @param order The limit order.
                                /// @return orderHash The order hash.
                                function getLimitOrderHash(LibNativeOrder.LimitOrder calldata order) external view returns (bytes32 orderHash);
                                /// @dev Get the canonical hash of an RFQ order.
                                /// @param order The RFQ order.
                                /// @return orderHash The order hash.
                                function getRfqOrderHash(LibNativeOrder.RfqOrder calldata order) external view returns (bytes32 orderHash);
                                /// @dev Get the protocol fee multiplier. This should be multiplied by the
                                ///      gas price to arrive at the required protocol fee to fill a native order.
                                /// @return multiplier The protocol fee multiplier.
                                function getProtocolFeeMultiplier() external view returns (uint32 multiplier);
                                /// @dev Get order info, fillable amount, and signature validity for a limit order.
                                ///      Fillable amount is determined using balances and allowances of the maker.
                                /// @param order The limit order.
                                /// @param signature The order signature.
                                /// @return orderInfo Info about the order.
                                /// @return actualFillableTakerTokenAmount How much of the order is fillable
                                ///         based on maker funds, in taker tokens.
                                /// @return isSignatureValid Whether the signature is valid.
                                function getLimitOrderRelevantState(
                                    LibNativeOrder.LimitOrder calldata order,
                                    LibSignature.Signature calldata signature
                                )
                                    external
                                    view
                                    returns (
                                        LibNativeOrder.OrderInfo memory orderInfo,
                                        uint128 actualFillableTakerTokenAmount,
                                        bool isSignatureValid
                                    );
                                /// @dev Get order info, fillable amount, and signature validity for an RFQ order.
                                ///      Fillable amount is determined using balances and allowances of the maker.
                                /// @param order The RFQ order.
                                /// @param signature The order signature.
                                /// @return orderInfo Info about the order.
                                /// @return actualFillableTakerTokenAmount How much of the order is fillable
                                ///         based on maker funds, in taker tokens.
                                /// @return isSignatureValid Whether the signature is valid.
                                function getRfqOrderRelevantState(
                                    LibNativeOrder.RfqOrder calldata order,
                                    LibSignature.Signature calldata signature
                                )
                                    external
                                    view
                                    returns (
                                        LibNativeOrder.OrderInfo memory orderInfo,
                                        uint128 actualFillableTakerTokenAmount,
                                        bool isSignatureValid
                                    );
                                /// @dev Batch version of `getLimitOrderRelevantState()`, without reverting.
                                ///      Orders that would normally cause `getLimitOrderRelevantState()`
                                ///      to revert will have empty results.
                                /// @param orders The limit orders.
                                /// @param signatures The order signatures.
                                /// @return orderInfos Info about the orders.
                                /// @return actualFillableTakerTokenAmounts How much of each order is fillable
                                ///         based on maker funds, in taker tokens.
                                /// @return isSignatureValids Whether each signature is valid for the order.
                                function batchGetLimitOrderRelevantStates(
                                    LibNativeOrder.LimitOrder[] calldata orders,
                                    LibSignature.Signature[] calldata signatures
                                )
                                    external
                                    view
                                    returns (
                                        LibNativeOrder.OrderInfo[] memory orderInfos,
                                        uint128[] memory actualFillableTakerTokenAmounts,
                                        bool[] memory isSignatureValids
                                    );
                                /// @dev Batch version of `getRfqOrderRelevantState()`, without reverting.
                                ///      Orders that would normally cause `getRfqOrderRelevantState()`
                                ///      to revert will have empty results.
                                /// @param orders The RFQ orders.
                                /// @param signatures The order signatures.
                                /// @return orderInfos Info about the orders.
                                /// @return actualFillableTakerTokenAmounts How much of each order is fillable
                                ///         based on maker funds, in taker tokens.
                                /// @return isSignatureValids Whether each signature is valid for the order.
                                function batchGetRfqOrderRelevantStates(
                                    LibNativeOrder.RfqOrder[] calldata orders,
                                    LibSignature.Signature[] calldata signatures
                                )
                                    external
                                    view
                                    returns (
                                        LibNativeOrder.OrderInfo[] memory orderInfos,
                                        uint128[] memory actualFillableTakerTokenAmounts,
                                        bool[] memory isSignatureValids
                                    );
                                /// @dev Register a signer who can sign on behalf of msg.sender
                                ///      This allows one to sign on behalf of a contract that calls this function
                                /// @param signer The address from which you plan to generate signatures
                                /// @param allowed True to register, false to unregister.
                                function registerAllowedOrderSigner(address signer, bool allowed) external;
                                /// @dev checks if a given address is registered to sign on behalf of a maker address
                                /// @param maker The maker address encoded in an order (can be a contract)
                                /// @param signer The address that is providing a signature
                                function isValidOrderSigner(address maker, address signer) external view returns (bool isAllowed);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "../../errors/LibSignatureRichErrors.sol";
                            /// @dev A library for validating signatures.
                            library LibSignature {
                                using LibRichErrorsV06 for bytes;
                                // '\\x19Ethereum Signed Message:\
                            32\\x00\\x00\\x00\\x00' in a word.
                                uint256 private constant ETH_SIGN_HASH_PREFIX = 0x19457468657265756d205369676e6564204d6573736167653a0a333200000000;
                                /// @dev Exclusive upper limit on ECDSA signatures 'R' values.
                                ///      The valid range is given by fig (282) of the yellow paper.
                                uint256 private constant ECDSA_SIGNATURE_R_LIMIT =
                                    uint256(0xfffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141);
                                /// @dev Exclusive upper limit on ECDSA signatures 'S' values.
                                ///      The valid range is given by fig (283) of the yellow paper.
                                uint256 private constant ECDSA_SIGNATURE_S_LIMIT = ECDSA_SIGNATURE_R_LIMIT / 2 + 1;
                                /// @dev Allowed signature types.
                                enum SignatureType {
                                    ILLEGAL,
                                    INVALID,
                                    EIP712,
                                    ETHSIGN,
                                    PRESIGNED
                                }
                                /// @dev Encoded EC signature.
                                struct Signature {
                                    // How to validate the signature.
                                    SignatureType signatureType;
                                    // EC Signature data.
                                    uint8 v;
                                    // EC Signature data.
                                    bytes32 r;
                                    // EC Signature data.
                                    bytes32 s;
                                }
                                /// @dev Retrieve the signer of a signature.
                                ///      Throws if the signature can't be validated.
                                /// @param hash The hash that was signed.
                                /// @param signature The signature.
                                /// @return recovered The recovered signer address.
                                function getSignerOfHash(bytes32 hash, Signature memory signature) internal pure returns (address recovered) {
                                    // Ensure this is a signature type that can be validated against a hash.
                                    _validateHashCompatibleSignature(hash, signature);
                                    if (signature.signatureType == SignatureType.EIP712) {
                                        // Signed using EIP712
                                        recovered = ecrecover(hash, signature.v, signature.r, signature.s);
                                    } else if (signature.signatureType == SignatureType.ETHSIGN) {
                                        // Signed using `eth_sign`
                                        // Need to hash `hash` with "\\x19Ethereum Signed Message:\
                            32" prefix
                                        // in packed encoding.
                                        bytes32 ethSignHash;
                                        assembly {
                                            // Use scratch space
                                            mstore(0, ETH_SIGN_HASH_PREFIX) // length of 28 bytes
                                            mstore(28, hash) // length of 32 bytes
                                            ethSignHash := keccak256(0, 60)
                                        }
                                        recovered = ecrecover(ethSignHash, signature.v, signature.r, signature.s);
                                    }
                                    // `recovered` can be null if the signature values are out of range.
                                    if (recovered == address(0)) {
                                        LibSignatureRichErrors
                                            .SignatureValidationError(LibSignatureRichErrors.SignatureValidationErrorCodes.BAD_SIGNATURE_DATA, hash)
                                            .rrevert();
                                    }
                                }
                                /// @dev Validates that a signature is compatible with a hash signee.
                                /// @param hash The hash that was signed.
                                /// @param signature The signature.
                                function _validateHashCompatibleSignature(bytes32 hash, Signature memory signature) private pure {
                                    // Ensure the r and s are within malleability limits.
                                    if (uint256(signature.r) >= ECDSA_SIGNATURE_R_LIMIT || uint256(signature.s) >= ECDSA_SIGNATURE_S_LIMIT) {
                                        LibSignatureRichErrors
                                            .SignatureValidationError(LibSignatureRichErrors.SignatureValidationErrorCodes.BAD_SIGNATURE_DATA, hash)
                                            .rrevert();
                                    }
                                    // Always illegal signature.
                                    if (signature.signatureType == SignatureType.ILLEGAL) {
                                        LibSignatureRichErrors
                                            .SignatureValidationError(LibSignatureRichErrors.SignatureValidationErrorCodes.ILLEGAL, hash)
                                            .rrevert();
                                    }
                                    // Always invalid.
                                    if (signature.signatureType == SignatureType.INVALID) {
                                        LibSignatureRichErrors
                                            .SignatureValidationError(LibSignatureRichErrors.SignatureValidationErrorCodes.ALWAYS_INVALID, hash)
                                            .rrevert();
                                    }
                                    // If a feature supports pre-signing, it wouldn't use
                                    // `getSignerOfHash` on a pre-signed order.
                                    if (signature.signatureType == SignatureType.PRESIGNED) {
                                        LibSignatureRichErrors
                                            .SignatureValidationError(LibSignatureRichErrors.SignatureValidationErrorCodes.UNSUPPORTED, hash)
                                            .rrevert();
                                    }
                                    // Solidity should check that the signature type is within enum range for us
                                    // when abi-decoding.
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibSignatureRichErrors {
                                enum SignatureValidationErrorCodes {
                                    ALWAYS_INVALID,
                                    INVALID_LENGTH,
                                    UNSUPPORTED,
                                    ILLEGAL,
                                    WRONG_SIGNER,
                                    BAD_SIGNATURE_DATA
                                }
                                function SignatureValidationError(
                                    SignatureValidationErrorCodes code,
                                    bytes32 hash,
                                    address signerAddress,
                                    bytes memory signature
                                ) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("SignatureValidationError(uint8,bytes32,address,bytes)")),
                                            code,
                                            hash,
                                            signerAddress,
                                            signature
                                        );
                                }
                                function SignatureValidationError(
                                    SignatureValidationErrorCodes code,
                                    bytes32 hash
                                ) internal pure returns (bytes memory) {
                                    return abi.encodeWithSelector(bytes4(keccak256("SignatureValidationError(uint8,bytes32)")), code, hash);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            import "../../errors/LibNativeOrdersRichErrors.sol";
                            /// @dev A library for common native order operations.
                            library LibNativeOrder {
                                using LibSafeMathV06 for uint256;
                                using LibRichErrorsV06 for bytes;
                                enum OrderStatus {
                                    INVALID,
                                    FILLABLE,
                                    FILLED,
                                    CANCELLED,
                                    EXPIRED
                                }
                                /// @dev A standard OTC or OO limit order.
                                struct LimitOrder {
                                    IERC20Token makerToken;
                                    IERC20Token takerToken;
                                    uint128 makerAmount;
                                    uint128 takerAmount;
                                    uint128 takerTokenFeeAmount;
                                    address maker;
                                    address taker;
                                    address sender;
                                    address feeRecipient;
                                    bytes32 pool;
                                    uint64 expiry;
                                    uint256 salt;
                                }
                                /// @dev An RFQ limit order.
                                struct RfqOrder {
                                    IERC20Token makerToken;
                                    IERC20Token takerToken;
                                    uint128 makerAmount;
                                    uint128 takerAmount;
                                    address maker;
                                    address taker;
                                    address txOrigin;
                                    bytes32 pool;
                                    uint64 expiry;
                                    uint256 salt;
                                }
                                /// @dev An OTC limit order.
                                struct OtcOrder {
                                    IERC20Token makerToken;
                                    IERC20Token takerToken;
                                    uint128 makerAmount;
                                    uint128 takerAmount;
                                    address maker;
                                    address taker;
                                    address txOrigin;
                                    uint256 expiryAndNonce; // [uint64 expiry, uint64 nonceBucket, uint128 nonce]
                                }
                                /// @dev Info on a limit or RFQ order.
                                struct OrderInfo {
                                    bytes32 orderHash;
                                    OrderStatus status;
                                    uint128 takerTokenFilledAmount;
                                }
                                /// @dev Info on an OTC order.
                                struct OtcOrderInfo {
                                    bytes32 orderHash;
                                    OrderStatus status;
                                }
                                uint256 private constant UINT_128_MASK = (1 << 128) - 1;
                                uint256 private constant UINT_64_MASK = (1 << 64) - 1;
                                uint256 private constant ADDRESS_MASK = (1 << 160) - 1;
                                // The type hash for limit orders, which is:
                                // keccak256(abi.encodePacked(
                                //     "LimitOrder(",
                                //       "address makerToken,",
                                //       "address takerToken,",
                                //       "uint128 makerAmount,",
                                //       "uint128 takerAmount,",
                                //       "uint128 takerTokenFeeAmount,",
                                //       "address maker,",
                                //       "address taker,",
                                //       "address sender,",
                                //       "address feeRecipient,",
                                //       "bytes32 pool,",
                                //       "uint64 expiry,",
                                //       "uint256 salt"
                                //     ")"
                                // ))
                                uint256 private constant _LIMIT_ORDER_TYPEHASH = 0xce918627cb55462ddbb85e73de69a8b322f2bc88f4507c52fcad6d4c33c29d49;
                                // The type hash for RFQ orders, which is:
                                // keccak256(abi.encodePacked(
                                //     "RfqOrder(",
                                //       "address makerToken,",
                                //       "address takerToken,",
                                //       "uint128 makerAmount,",
                                //       "uint128 takerAmount,",
                                //       "address maker,",
                                //       "address taker,",
                                //       "address txOrigin,",
                                //       "bytes32 pool,",
                                //       "uint64 expiry,",
                                //       "uint256 salt"
                                //     ")"
                                // ))
                                uint256 private constant _RFQ_ORDER_TYPEHASH = 0xe593d3fdfa8b60e5e17a1b2204662ecbe15c23f2084b9ad5bae40359540a7da9;
                                // The type hash for OTC orders, which is:
                                // keccak256(abi.encodePacked(
                                //     "OtcOrder(",
                                //       "address makerToken,",
                                //       "address takerToken,",
                                //       "uint128 makerAmount,",
                                //       "uint128 takerAmount,",
                                //       "address maker,",
                                //       "address taker,",
                                //       "address txOrigin,",
                                //       "uint256 expiryAndNonce"
                                //     ")"
                                // ))
                                uint256 private constant _OTC_ORDER_TYPEHASH = 0x2f754524de756ae72459efbe1ec88c19a745639821de528ac3fb88f9e65e35c8;
                                /// @dev Get the struct hash of a limit order.
                                /// @param order The limit order.
                                /// @return structHash The struct hash of the order.
                                function getLimitOrderStructHash(LimitOrder memory order) internal pure returns (bytes32 structHash) {
                                    // The struct hash is:
                                    // keccak256(abi.encode(
                                    //   TYPE_HASH,
                                    //   order.makerToken,
                                    //   order.takerToken,
                                    //   order.makerAmount,
                                    //   order.takerAmount,
                                    //   order.takerTokenFeeAmount,
                                    //   order.maker,
                                    //   order.taker,
                                    //   order.sender,
                                    //   order.feeRecipient,
                                    //   order.pool,
                                    //   order.expiry,
                                    //   order.salt,
                                    // ))
                                    assembly {
                                        let mem := mload(0x40)
                                        mstore(mem, _LIMIT_ORDER_TYPEHASH)
                                        // order.makerToken;
                                        mstore(add(mem, 0x20), and(ADDRESS_MASK, mload(order)))
                                        // order.takerToken;
                                        mstore(add(mem, 0x40), and(ADDRESS_MASK, mload(add(order, 0x20))))
                                        // order.makerAmount;
                                        mstore(add(mem, 0x60), and(UINT_128_MASK, mload(add(order, 0x40))))
                                        // order.takerAmount;
                                        mstore(add(mem, 0x80), and(UINT_128_MASK, mload(add(order, 0x60))))
                                        // order.takerTokenFeeAmount;
                                        mstore(add(mem, 0xA0), and(UINT_128_MASK, mload(add(order, 0x80))))
                                        // order.maker;
                                        mstore(add(mem, 0xC0), and(ADDRESS_MASK, mload(add(order, 0xA0))))
                                        // order.taker;
                                        mstore(add(mem, 0xE0), and(ADDRESS_MASK, mload(add(order, 0xC0))))
                                        // order.sender;
                                        mstore(add(mem, 0x100), and(ADDRESS_MASK, mload(add(order, 0xE0))))
                                        // order.feeRecipient;
                                        mstore(add(mem, 0x120), and(ADDRESS_MASK, mload(add(order, 0x100))))
                                        // order.pool;
                                        mstore(add(mem, 0x140), mload(add(order, 0x120)))
                                        // order.expiry;
                                        mstore(add(mem, 0x160), and(UINT_64_MASK, mload(add(order, 0x140))))
                                        // order.salt;
                                        mstore(add(mem, 0x180), mload(add(order, 0x160)))
                                        structHash := keccak256(mem, 0x1A0)
                                    }
                                }
                                /// @dev Get the struct hash of a RFQ order.
                                /// @param order The RFQ order.
                                /// @return structHash The struct hash of the order.
                                function getRfqOrderStructHash(RfqOrder memory order) internal pure returns (bytes32 structHash) {
                                    // The struct hash is:
                                    // keccak256(abi.encode(
                                    //   TYPE_HASH,
                                    //   order.makerToken,
                                    //   order.takerToken,
                                    //   order.makerAmount,
                                    //   order.takerAmount,
                                    //   order.maker,
                                    //   order.taker,
                                    //   order.txOrigin,
                                    //   order.pool,
                                    //   order.expiry,
                                    //   order.salt,
                                    // ))
                                    assembly {
                                        let mem := mload(0x40)
                                        mstore(mem, _RFQ_ORDER_TYPEHASH)
                                        // order.makerToken;
                                        mstore(add(mem, 0x20), and(ADDRESS_MASK, mload(order)))
                                        // order.takerToken;
                                        mstore(add(mem, 0x40), and(ADDRESS_MASK, mload(add(order, 0x20))))
                                        // order.makerAmount;
                                        mstore(add(mem, 0x60), and(UINT_128_MASK, mload(add(order, 0x40))))
                                        // order.takerAmount;
                                        mstore(add(mem, 0x80), and(UINT_128_MASK, mload(add(order, 0x60))))
                                        // order.maker;
                                        mstore(add(mem, 0xA0), and(ADDRESS_MASK, mload(add(order, 0x80))))
                                        // order.taker;
                                        mstore(add(mem, 0xC0), and(ADDRESS_MASK, mload(add(order, 0xA0))))
                                        // order.txOrigin;
                                        mstore(add(mem, 0xE0), and(ADDRESS_MASK, mload(add(order, 0xC0))))
                                        // order.pool;
                                        mstore(add(mem, 0x100), mload(add(order, 0xE0)))
                                        // order.expiry;
                                        mstore(add(mem, 0x120), and(UINT_64_MASK, mload(add(order, 0x100))))
                                        // order.salt;
                                        mstore(add(mem, 0x140), mload(add(order, 0x120)))
                                        structHash := keccak256(mem, 0x160)
                                    }
                                }
                                /// @dev Get the struct hash of an OTC order.
                                /// @param order The OTC order.
                                /// @return structHash The struct hash of the order.
                                function getOtcOrderStructHash(OtcOrder memory order) internal pure returns (bytes32 structHash) {
                                    // The struct hash is:
                                    // keccak256(abi.encode(
                                    //   TYPE_HASH,
                                    //   order.makerToken,
                                    //   order.takerToken,
                                    //   order.makerAmount,
                                    //   order.takerAmount,
                                    //   order.maker,
                                    //   order.taker,
                                    //   order.txOrigin,
                                    //   order.expiryAndNonce,
                                    // ))
                                    assembly {
                                        let mem := mload(0x40)
                                        mstore(mem, _OTC_ORDER_TYPEHASH)
                                        // order.makerToken;
                                        mstore(add(mem, 0x20), and(ADDRESS_MASK, mload(order)))
                                        // order.takerToken;
                                        mstore(add(mem, 0x40), and(ADDRESS_MASK, mload(add(order, 0x20))))
                                        // order.makerAmount;
                                        mstore(add(mem, 0x60), and(UINT_128_MASK, mload(add(order, 0x40))))
                                        // order.takerAmount;
                                        mstore(add(mem, 0x80), and(UINT_128_MASK, mload(add(order, 0x60))))
                                        // order.maker;
                                        mstore(add(mem, 0xA0), and(ADDRESS_MASK, mload(add(order, 0x80))))
                                        // order.taker;
                                        mstore(add(mem, 0xC0), and(ADDRESS_MASK, mload(add(order, 0xA0))))
                                        // order.txOrigin;
                                        mstore(add(mem, 0xE0), and(ADDRESS_MASK, mload(add(order, 0xC0))))
                                        // order.expiryAndNonce;
                                        mstore(add(mem, 0x100), mload(add(order, 0xE0)))
                                        structHash := keccak256(mem, 0x120)
                                    }
                                }
                                /// @dev Refund any leftover protocol fees in `msg.value` to `msg.sender`.
                                /// @param ethProtocolFeePaid How much ETH was paid in protocol fees.
                                function refundExcessProtocolFeeToSender(uint256 ethProtocolFeePaid) internal {
                                    if (msg.value > ethProtocolFeePaid && msg.sender != address(this)) {
                                        uint256 refundAmount = msg.value.safeSub(ethProtocolFeePaid);
                                        (bool success, ) = msg.sender.call{value: refundAmount}("");
                                        if (!success) {
                                            LibNativeOrdersRichErrors.ProtocolFeeRefundFailed(msg.sender, refundAmount).rrevert();
                                        }
                                    }
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibNativeOrdersRichErrors {
                                function ProtocolFeeRefundFailed(address receiver, uint256 refundAmount) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("ProtocolFeeRefundFailed(address,uint256)")),
                                            receiver,
                                            refundAmount
                                        );
                                }
                                function OrderNotFillableByOriginError(
                                    bytes32 orderHash,
                                    address txOrigin,
                                    address orderTxOrigin
                                ) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("OrderNotFillableByOriginError(bytes32,address,address)")),
                                            orderHash,
                                            txOrigin,
                                            orderTxOrigin
                                        );
                                }
                                function OrderNotFillableError(bytes32 orderHash, uint8 orderStatus) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(bytes4(keccak256("OrderNotFillableError(bytes32,uint8)")), orderHash, orderStatus);
                                }
                                function OrderNotSignedByMakerError(
                                    bytes32 orderHash,
                                    address signer,
                                    address maker
                                ) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("OrderNotSignedByMakerError(bytes32,address,address)")),
                                            orderHash,
                                            signer,
                                            maker
                                        );
                                }
                                function InvalidSignerError(address maker, address signer) internal pure returns (bytes memory) {
                                    return abi.encodeWithSelector(bytes4(keccak256("InvalidSignerError(address,address)")), maker, signer);
                                }
                                function OrderNotFillableBySenderError(
                                    bytes32 orderHash,
                                    address sender,
                                    address orderSender
                                ) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("OrderNotFillableBySenderError(bytes32,address,address)")),
                                            orderHash,
                                            sender,
                                            orderSender
                                        );
                                }
                                function OrderNotFillableByTakerError(
                                    bytes32 orderHash,
                                    address taker,
                                    address orderTaker
                                ) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("OrderNotFillableByTakerError(bytes32,address,address)")),
                                            orderHash,
                                            taker,
                                            orderTaker
                                        );
                                }
                                function CancelSaltTooLowError(uint256 minValidSalt, uint256 oldMinValidSalt) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("CancelSaltTooLowError(uint256,uint256)")),
                                            minValidSalt,
                                            oldMinValidSalt
                                        );
                                }
                                function FillOrKillFailedError(
                                    bytes32 orderHash,
                                    uint256 takerTokenFilledAmount,
                                    uint256 takerTokenFillAmount
                                ) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("FillOrKillFailedError(bytes32,uint256,uint256)")),
                                            orderHash,
                                            takerTokenFilledAmount,
                                            takerTokenFillAmount
                                        );
                                }
                                function OnlyOrderMakerAllowed(
                                    bytes32 orderHash,
                                    address sender,
                                    address maker
                                ) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("OnlyOrderMakerAllowed(bytes32,address,address)")),
                                            orderHash,
                                            sender,
                                            maker
                                        );
                                }
                                function BatchFillIncompleteError(
                                    bytes32 orderHash,
                                    uint256 takerTokenFilledAmount,
                                    uint256 takerTokenFillAmount
                                ) internal pure returns (bytes memory) {
                                    return
                                        abi.encodeWithSelector(
                                            bytes4(keccak256("BatchFillIncompleteError(bytes32,uint256,uint256)")),
                                            orderHash,
                                            takerTokenFilledAmount,
                                            takerTokenFillAmount
                                        );
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../libs/LibSignature.sol";
                            import "../libs/LibNativeOrder.sol";
                            /// @dev Events emitted by NativeOrdersFeature.
                            interface INativeOrdersEvents {
                                /// @dev Emitted whenever a `LimitOrder` is filled.
                                /// @param orderHash The canonical hash of the order.
                                /// @param maker The maker of the order.
                                /// @param taker The taker of the order.
                                /// @param feeRecipient Fee recipient of the order.
                                /// @param takerTokenFilledAmount How much taker token was filled.
                                /// @param makerTokenFilledAmount How much maker token was filled.
                                /// @param protocolFeePaid How much protocol fee was paid.
                                /// @param pool The fee pool associated with this order.
                                event LimitOrderFilled(
                                    bytes32 orderHash,
                                    address maker,
                                    address taker,
                                    address feeRecipient,
                                    address makerToken,
                                    address takerToken,
                                    uint128 takerTokenFilledAmount,
                                    uint128 makerTokenFilledAmount,
                                    uint128 takerTokenFeeFilledAmount,
                                    uint256 protocolFeePaid,
                                    bytes32 pool
                                );
                                /// @dev Emitted whenever an `RfqOrder` is filled.
                                /// @param orderHash The canonical hash of the order.
                                /// @param maker The maker of the order.
                                /// @param taker The taker of the order.
                                /// @param takerTokenFilledAmount How much taker token was filled.
                                /// @param makerTokenFilledAmount How much maker token was filled.
                                /// @param pool The fee pool associated with this order.
                                event RfqOrderFilled(
                                    bytes32 orderHash,
                                    address maker,
                                    address taker,
                                    address makerToken,
                                    address takerToken,
                                    uint128 takerTokenFilledAmount,
                                    uint128 makerTokenFilledAmount,
                                    bytes32 pool
                                );
                                /// @dev Emitted whenever a limit or RFQ order is cancelled.
                                /// @param orderHash The canonical hash of the order.
                                /// @param maker The order maker.
                                event OrderCancelled(bytes32 orderHash, address maker);
                                /// @dev Emitted whenever Limit orders are cancelled by pair by a maker.
                                /// @param maker The maker of the order.
                                /// @param makerToken The maker token in a pair for the orders cancelled.
                                /// @param takerToken The taker token in a pair for the orders cancelled.
                                /// @param minValidSalt The new minimum valid salt an order with this pair must
                                ///        have.
                                event PairCancelledLimitOrders(address maker, address makerToken, address takerToken, uint256 minValidSalt);
                                /// @dev Emitted whenever RFQ orders are cancelled by pair by a maker.
                                /// @param maker The maker of the order.
                                /// @param makerToken The maker token in a pair for the orders cancelled.
                                /// @param takerToken The taker token in a pair for the orders cancelled.
                                /// @param minValidSalt The new minimum valid salt an order with this pair must
                                ///        have.
                                event PairCancelledRfqOrders(address maker, address makerToken, address takerToken, uint256 minValidSalt);
                                /// @dev Emitted when new addresses are allowed or disallowed to fill
                                ///      orders with a given txOrigin.
                                /// @param origin The address doing the allowing.
                                /// @param addrs The address being allowed/disallowed.
                                /// @param allowed Indicates whether the address should be allowed.
                                event RfqOrderOriginsAllowed(address origin, address[] addrs, bool allowed);
                                /// @dev Emitted when new order signers are registered
                                /// @param maker The maker address that is registering a designated signer.
                                /// @param signer The address that will sign on behalf of maker.
                                /// @param allowed Indicates whether the address should be allowed.
                                event OrderSignerRegistered(address maker, address signer, bool allowed);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            interface IBridgeAdapter {
                                struct BridgeOrder {
                                    // Upper 16 bytes: uint128 protocol ID (right-aligned)
                                    // Lower 16 bytes: ASCII source name (left-aligned)
                                    bytes32 source;
                                    uint256 takerTokenAmount;
                                    uint256 makerTokenAmount;
                                    bytes bridgeData;
                                }
                                /// @dev Emitted when tokens are swapped with an external source.
                                /// @param source A unique ID for the source, where the upper 16 bytes
                                ///        encodes the (right-aligned) uint128 protocol ID and the
                                ///        lower 16 bytes encodes an ASCII source name.
                                /// @param inputToken The token the bridge is converting from.
                                /// @param outputToken The token the bridge is converting to.
                                /// @param inputTokenAmount Amount of input token sold.
                                /// @param outputTokenAmount Amount of output token bought.
                                event BridgeFill(
                                    bytes32 source,
                                    IERC20Token inputToken,
                                    IERC20Token outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 outputTokenAmount
                                );
                                function isSupportedSource(bytes32 source) external returns (bool isSupported);
                                function trade(
                                    BridgeOrder calldata order,
                                    IERC20Token sellToken,
                                    IERC20Token buyToken,
                                    uint256 sellAmount
                                ) external returns (uint256 boughtAmount);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "../errors/LibTransformERC20RichErrors.sol";
                            import "./IERC20Transformer.sol";
                            /// @dev Abstract base class for transformers.
                            abstract contract Transformer is IERC20Transformer {
                                using LibRichErrorsV06 for bytes;
                                /// @dev The address of the deployer.
                                address public immutable deployer;
                                /// @dev The original address of this contract.
                                address internal immutable _implementation;
                                /// @dev Create this contract.
                                constructor() public {
                                    deployer = msg.sender;
                                    _implementation = address(this);
                                }
                                /// @dev Destruct this contract. Only callable by the deployer and will not
                                ///      succeed in the context of a delegatecall (from another contract).
                                /// @param ethRecipient The recipient of ETH held in this contract.
                                function die(address payable ethRecipient) external virtual {
                                    // Only the deployer can call this.
                                    if (msg.sender != deployer) {
                                        LibTransformERC20RichErrors.OnlyCallableByDeployerError(msg.sender, deployer).rrevert();
                                    }
                                    // Must be executing our own context.
                                    if (address(this) != _implementation) {
                                        LibTransformERC20RichErrors.InvalidExecutionContextError(address(this), _implementation).rrevert();
                                    }
                                    selfdestruct(ethRecipient);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            /// @dev A transformation callback used in `TransformERC20.transformERC20()`.
                            interface IERC20Transformer {
                                /// @dev Context information to pass into `transform()` by `TransformERC20.transformERC20()`.
                                struct TransformContext {
                                    // The caller of `TransformERC20.transformERC20()`.
                                    address payable sender;
                                    // The recipient address, which may be distinct from `sender` e.g. in
                                    // meta-transactions.
                                    address payable recipient;
                                    // Arbitrary data to pass to the transformer.
                                    bytes data;
                                }
                                /// @dev Called from `TransformERC20.transformERC20()`. This will be
                                ///      delegatecalled in the context of the FlashWallet instance being used.
                                /// @param context Context information.
                                /// @return success The success bytes (`LibERC20Transformer.TRANSFORMER_SUCCESS`).
                                function transform(TransformContext calldata context) external returns (bytes4 success);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            library LibERC20Transformer {
                                using LibERC20TokenV06 for IERC20Token;
                                /// @dev ETH pseudo-token address.
                                address internal constant ETH_TOKEN_ADDRESS = 0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE;
                                /// @dev ETH pseudo-token.
                                IERC20Token internal constant ETH_TOKEN = IERC20Token(ETH_TOKEN_ADDRESS);
                                /// @dev Return value indicating success in `IERC20Transformer.transform()`.
                                ///      This is just `keccak256('TRANSFORMER_SUCCESS')`.
                                bytes4 internal constant TRANSFORMER_SUCCESS = 0x13c9929e;
                                /// @dev Transfer ERC20 tokens and ETH. Since it relies on `transfer` it may run out of gas when
                                /// the `recipient` is a smart contract wallet. See `unsafeTransformerTransfer` for smart contract
                                /// compatible transfer.
                                /// @param token An ERC20 or the ETH pseudo-token address (`ETH_TOKEN_ADDRESS`).
                                /// @param to The recipient.
                                /// @param amount The transfer amount.
                                function transformerTransfer(IERC20Token token, address payable to, uint256 amount) internal {
                                    if (isTokenETH(token)) {
                                        to.transfer(amount);
                                    } else {
                                        token.compatTransfer(to, amount);
                                    }
                                }
                                /// @dev Transfer ERC20 tokens and ETH. For ETH transfer. It's not safe from re-entrancy attacks and the
                                /// caller is responsible for gurading against a potential re-entrancy attack.
                                /// @param token An ERC20 or the ETH pseudo-token address (`ETH_TOKEN_ADDRESS`).
                                /// @param to The recipient.
                                /// @param amount The transfer amount.
                                function unsafeTransformerTransfer(IERC20Token token, address payable to, uint256 amount) internal {
                                    if (isTokenETH(token)) {
                                        (bool sent, ) = to.call{value: amount}("");
                                        require(sent, "LibERC20Transformer/FAILED_TO_SEND_ETHER");
                                    } else {
                                        token.compatTransfer(to, amount);
                                    }
                                }
                                /// @dev Check if a token is the ETH pseudo-token.
                                /// @param token The token to check.
                                /// @return isETH `true` if the token is the ETH pseudo-token.
                                function isTokenETH(IERC20Token token) internal pure returns (bool isETH) {
                                    return address(token) == ETH_TOKEN_ADDRESS;
                                }
                                /// @dev Check the balance of an ERC20 token or ETH.
                                /// @param token An ERC20 or the ETH pseudo-token address (`ETH_TOKEN_ADDRESS`).
                                /// @param owner Holder of the tokens.
                                /// @return tokenBalance The balance of `owner`.
                                function getTokenBalanceOf(IERC20Token token, address owner) internal view returns (uint256 tokenBalance) {
                                    if (isTokenETH(token)) {
                                        return owner.balance;
                                    }
                                    return token.balanceOf(owner);
                                }
                                /// @dev RLP-encode a 32-bit or less account nonce.
                                /// @param nonce A positive integer in the range 0 <= nonce < 2^32.
                                /// @return rlpNonce The RLP encoding.
                                function rlpEncodeNonce(uint32 nonce) internal pure returns (bytes memory rlpNonce) {
                                    // See https://github.com/ethereum/wiki/wiki/RLP for RLP encoding rules.
                                    if (nonce == 0) {
                                        rlpNonce = new bytes(1);
                                        rlpNonce[0] = 0x80;
                                    } else if (nonce < 0x80) {
                                        rlpNonce = new bytes(1);
                                        rlpNonce[0] = bytes1(uint8(nonce));
                                    } else if (nonce <= 0xFF) {
                                        rlpNonce = new bytes(2);
                                        rlpNonce[0] = 0x81;
                                        rlpNonce[1] = bytes1(uint8(nonce));
                                    } else if (nonce <= 0xFFFF) {
                                        rlpNonce = new bytes(3);
                                        rlpNonce[0] = 0x82;
                                        rlpNonce[1] = bytes1(uint8((nonce & 0xFF00) >> 8));
                                        rlpNonce[2] = bytes1(uint8(nonce));
                                    } else if (nonce <= 0xFFFFFF) {
                                        rlpNonce = new bytes(4);
                                        rlpNonce[0] = 0x83;
                                        rlpNonce[1] = bytes1(uint8((nonce & 0xFF0000) >> 16));
                                        rlpNonce[2] = bytes1(uint8((nonce & 0xFF00) >> 8));
                                        rlpNonce[3] = bytes1(uint8(nonce));
                                    } else {
                                        rlpNonce = new bytes(5);
                                        rlpNonce[0] = 0x84;
                                        rlpNonce[1] = bytes1(uint8((nonce & 0xFF000000) >> 24));
                                        rlpNonce[2] = bytes1(uint8((nonce & 0xFF0000) >> 16));
                                        rlpNonce[3] = bytes1(uint8((nonce & 0xFF00) >> 8));
                                        rlpNonce[4] = bytes1(uint8(nonce));
                                    }
                                }
                                /// @dev Compute the expected deployment address by `deployer` at
                                ///      the nonce given by `deploymentNonce`.
                                /// @param deployer The address of the deployer.
                                /// @param deploymentNonce The nonce that the deployer had when deploying
                                ///        a contract.
                                /// @return deploymentAddress The deployment address.
                                function getDeployedAddress(
                                    address deployer,
                                    uint32 deploymentNonce
                                ) internal pure returns (address payable deploymentAddress) {
                                    // The address of if a deployed contract is the lower 20 bytes of the
                                    // hash of the RLP-encoded deployer's account address + account nonce.
                                    // See: https://ethereum.stackexchange.com/questions/760/how-is-the-address-of-an-ethereum-contract-computed
                                    bytes memory rlpNonce = rlpEncodeNonce(deploymentNonce);
                                    return
                                        address(
                                            uint160(
                                                uint256(
                                                    keccak256(
                                                        abi.encodePacked(
                                                            bytes1(uint8(0xC0 + 21 + rlpNonce.length)),
                                                            bytes1(uint8(0x80 + 20)),
                                                            deployer,
                                                            rlpNonce
                                                        )
                                                    )
                                                )
                                            )
                                        );
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "./features/interfaces/IOwnableFeature.sol";
                            import "./features/interfaces/ISimpleFunctionRegistryFeature.sol";
                            import "./features/interfaces/ITokenSpenderFeature.sol";
                            import "./features/interfaces/ITransformERC20Feature.sol";
                            import "./features/interfaces/IMetaTransactionsFeature.sol";
                            import "./features/interfaces/IMetaTransactionsFeatureV2.sol";
                            import "./features/interfaces/IUniswapFeature.sol";
                            import "./features/interfaces/IUniswapV3Feature.sol";
                            import "./features/interfaces/IPancakeSwapFeature.sol";
                            import "./features/interfaces/ILiquidityProviderFeature.sol";
                            import "./features/interfaces/INativeOrdersFeature.sol";
                            import "./features/interfaces/IBatchFillNativeOrdersFeature.sol";
                            import "./features/interfaces/IMultiplexFeature.sol";
                            import "./features/interfaces/IOtcOrdersFeature.sol";
                            import "./features/interfaces/IFundRecoveryFeature.sol";
                            import "./features/interfaces/IERC721OrdersFeature.sol";
                            import "./features/interfaces/IERC1155OrdersFeature.sol";
                            import "./features/interfaces/IERC165Feature.sol";
                            /// @dev Interface for a fully featured Exchange Proxy.
                            interface IZeroEx is
                                IOwnableFeature,
                                ISimpleFunctionRegistryFeature,
                                ITransformERC20Feature,
                                IMetaTransactionsFeature,
                                IMetaTransactionsFeatureV2,
                                IUniswapFeature,
                                IUniswapV3Feature,
                                IPancakeSwapFeature,
                                ILiquidityProviderFeature,
                                INativeOrdersFeature,
                                IBatchFillNativeOrdersFeature,
                                IMultiplexFeature,
                                IOtcOrdersFeature,
                                IFundRecoveryFeature,
                                IERC721OrdersFeature,
                                IERC1155OrdersFeature,
                                IERC165Feature
                            {
                                /// @dev Fallback for just receiving ether.
                                receive() external payable;
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/interfaces/IOwnableV06.sol";
                            /// @dev Owner management and migration features.
                            interface IOwnableFeature is IOwnableV06 {
                                /// @dev Emitted when `migrate()` is called.
                                /// @param caller The caller of `migrate()`.
                                /// @param migrator The migration contract.
                                /// @param newOwner The address of the new owner.
                                event Migrated(address caller, address migrator, address newOwner);
                                /// @dev Execute a migration function in the context of the ZeroEx contract.
                                ///      The result of the function being called should be the magic bytes
                                ///      0x2c64c5ef (`keccack('MIGRATE_SUCCESS')`). Only callable by the owner.
                                ///      The owner will be temporarily set to `address(this)` inside the call.
                                ///      Before returning, the owner will be set to `newOwner`.
                                /// @param target The migrator contract address.
                                /// @param newOwner The address of the new owner.
                                /// @param data The call data.
                                function migrate(address target, bytes calldata data, address newOwner) external;
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            interface IOwnableV06 {
                                /// @dev Emitted by Ownable when ownership is transferred.
                                /// @param previousOwner The previous owner of the contract.
                                /// @param newOwner The new owner of the contract.
                                event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
                                /// @dev Transfers ownership of the contract to a new address.
                                /// @param newOwner The address that will become the owner.
                                function transferOwnership(address newOwner) external;
                                /// @dev The owner of this contract.
                                /// @return ownerAddress The owner address.
                                function owner() external view returns (address ownerAddress);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            /// @dev Basic registry management features.
                            interface ISimpleFunctionRegistryFeature {
                                /// @dev A function implementation was updated via `extend()` or `rollback()`.
                                /// @param selector The function selector.
                                /// @param oldImpl The implementation contract address being replaced.
                                /// @param newImpl The replacement implementation contract address.
                                event ProxyFunctionUpdated(bytes4 indexed selector, address oldImpl, address newImpl);
                                /// @dev Roll back to a prior implementation of a function.
                                /// @param selector The function selector.
                                /// @param targetImpl The address of an older implementation of the function.
                                function rollback(bytes4 selector, address targetImpl) external;
                                /// @dev Register or replace a function.
                                /// @param selector The function selector.
                                /// @param impl The implementation contract for the function.
                                function extend(bytes4 selector, address impl) external;
                                /// @dev Retrieve the length of the rollback history for a function.
                                /// @param selector The function selector.
                                /// @return rollbackLength The number of items in the rollback history for
                                ///         the function.
                                function getRollbackLength(bytes4 selector) external view returns (uint256 rollbackLength);
                                /// @dev Retrieve an entry in the rollback history for a function.
                                /// @param selector The function selector.
                                /// @param idx The index in the rollback history.
                                /// @return impl An implementation address for the function at
                                ///         index `idx`.
                                function getRollbackEntryAtIndex(bytes4 selector, uint256 idx) external view returns (address impl);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            /// @dev Feature that allows spending token allowances.
                            interface ITokenSpenderFeature {
                                /// @dev Transfers ERC20 tokens from `owner` to `to`.
                                ///      Only callable from within.
                                /// @param token The token to spend.
                                /// @param owner The owner of the tokens.
                                /// @param to The recipient of the tokens.
                                /// @param amount The amount of `token` to transfer.
                                function _spendERC20Tokens(IERC20Token token, address owner, address to, uint256 amount) external;
                                /// @dev Gets the maximum amount of an ERC20 token `token` that can be
                                ///      pulled from `owner`.
                                /// @param token The token to spend.
                                /// @param owner The owner of the tokens.
                                /// @return amount The amount of tokens that can be pulled.
                                function getSpendableERC20BalanceOf(IERC20Token token, address owner) external view returns (uint256 amount);
                                /// @dev Get the address of the allowance target.
                                /// @return target The target of token allowances.
                                function getAllowanceTarget() external view returns (address target);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "../../transformers/IERC20Transformer.sol";
                            import "../../external/IFlashWallet.sol";
                            /// @dev Feature to composably transform between ERC20 tokens.
                            interface ITransformERC20Feature {
                                /// @dev Defines a transformation to run in `transformERC20()`.
                                struct Transformation {
                                    // The deployment nonce for the transformer.
                                    // The address of the transformer contract will be derived from this
                                    // value.
                                    uint32 deploymentNonce;
                                    // Arbitrary data to pass to the transformer.
                                    bytes data;
                                }
                                /// @dev Arguments for `_transformERC20()`.
                                struct TransformERC20Args {
                                    // The taker address.
                                    address payable taker;
                                    // The token being provided by the taker.
                                    // If `0xeee...`, ETH is implied and should be provided with the call.`
                                    IERC20Token inputToken;
                                    // The token to be acquired by the taker.
                                    // `0xeee...` implies ETH.
                                    IERC20Token outputToken;
                                    // The amount of `inputToken` to take from the taker.
                                    // If set to `uint256(-1)`, the entire spendable balance of the taker
                                    // will be solt.
                                    uint256 inputTokenAmount;
                                    // The minimum amount of `outputToken` the taker
                                    // must receive for the entire transformation to succeed. If set to zero,
                                    // the minimum output token transfer will not be asserted.
                                    uint256 minOutputTokenAmount;
                                    // The transformations to execute on the token balance(s)
                                    // in sequence.
                                    Transformation[] transformations;
                                    // Whether to use the Exchange Proxy's balance of `inputToken`.
                                    bool useSelfBalance;
                                    // The recipient of the bought `outputToken`.
                                    address payable recipient;
                                }
                                /// @dev Raised upon a successful `transformERC20`.
                                /// @param taker The taker (caller) address.
                                /// @param inputToken The token being provided by the taker.
                                ///        If `0xeee...`, ETH is implied and should be provided with the call.`
                                /// @param outputToken The token to be acquired by the taker.
                                ///        `0xeee...` implies ETH.
                                /// @param inputTokenAmount The amount of `inputToken` to take from the taker.
                                /// @param outputTokenAmount The amount of `outputToken` received by the taker.
                                event TransformedERC20(
                                    address indexed taker,
                                    address inputToken,
                                    address outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 outputTokenAmount
                                );
                                /// @dev Raised when `setTransformerDeployer()` is called.
                                /// @param transformerDeployer The new deployer address.
                                event TransformerDeployerUpdated(address transformerDeployer);
                                /// @dev Raised when `setQuoteSigner()` is called.
                                /// @param quoteSigner The new quote signer.
                                event QuoteSignerUpdated(address quoteSigner);
                                /// @dev Replace the allowed deployer for transformers.
                                ///      Only callable by the owner.
                                /// @param transformerDeployer The address of the new trusted deployer
                                ///        for transformers.
                                function setTransformerDeployer(address transformerDeployer) external;
                                /// @dev Replace the optional signer for `transformERC20()` calldata.
                                ///      Only callable by the owner.
                                /// @param quoteSigner The address of the new calldata signer.
                                function setQuoteSigner(address quoteSigner) external;
                                /// @dev Deploy a new flash wallet instance and replace the current one with it.
                                ///      Useful if we somehow break the current wallet instance.
                                ///       Only callable by the owner.
                                /// @return wallet The new wallet instance.
                                function createTransformWallet() external returns (IFlashWallet wallet);
                                /// @dev Executes a series of transformations to convert an ERC20 `inputToken`
                                ///      to an ERC20 `outputToken`.
                                /// @param inputToken The token being provided by the sender.
                                ///        If `0xeee...`, ETH is implied and should be provided with the call.`
                                /// @param outputToken The token to be acquired by the sender.
                                ///        `0xeee...` implies ETH.
                                /// @param inputTokenAmount The amount of `inputToken` to take from the sender.
                                /// @param minOutputTokenAmount The minimum amount of `outputToken` the sender
                                ///        must receive for the entire transformation to succeed.
                                /// @param transformations The transformations to execute on the token balance(s)
                                ///        in sequence.
                                /// @return outputTokenAmount The amount of `outputToken` received by the sender.
                                function transformERC20(
                                    IERC20Token inputToken,
                                    IERC20Token outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 minOutputTokenAmount,
                                    Transformation[] calldata transformations
                                ) external payable returns (uint256 outputTokenAmount);
                                /// @dev Internal version of `transformERC20()`. Only callable from within.
                                /// @param args A `TransformERC20Args` struct.
                                /// @return outputTokenAmount The amount of `outputToken` received by the taker.
                                function _transformERC20(TransformERC20Args calldata args) external payable returns (uint256 outputTokenAmount);
                                /// @dev Return the current wallet instance that will serve as the execution
                                ///      context for transformations.
                                /// @return wallet The wallet instance.
                                function getTransformWallet() external view returns (IFlashWallet wallet);
                                /// @dev Return the allowed deployer for transformers.
                                /// @return deployer The transform deployer address.
                                function getTransformerDeployer() external view returns (address deployer);
                                /// @dev Return the optional signer for `transformERC20()` calldata.
                                /// @return signer The transform deployer address.
                                function getQuoteSigner() external view returns (address signer);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/interfaces/IOwnableV06.sol";
                            /// @dev A contract that can execute arbitrary calls from its owner.
                            interface IFlashWallet {
                                /// @dev Execute an arbitrary call. Only an authority can call this.
                                /// @param target The call target.
                                /// @param callData The call data.
                                /// @param value Ether to attach to the call.
                                /// @return resultData The data returned by the call.
                                function executeCall(
                                    address payable target,
                                    bytes calldata callData,
                                    uint256 value
                                ) external payable returns (bytes memory resultData);
                                /// @dev Execute an arbitrary delegatecall, in the context of this puppet.
                                ///      Only an authority can call this.
                                /// @param target The call target.
                                /// @param callData The call data.
                                /// @return resultData The data returned by the call.
                                function executeDelegateCall(
                                    address payable target,
                                    bytes calldata callData
                                ) external payable returns (bytes memory resultData);
                                /// @dev Allows the puppet to receive ETH.
                                receive() external payable;
                                /// @dev Fetch the immutable owner/deployer of this contract.
                                /// @return owner_ The immutable owner/deployer/
                                function owner() external view returns (address owner_);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "../libs/LibSignature.sol";
                            /// @dev Meta-transactions feature.
                            interface IMetaTransactionsFeature {
                                /// @dev Describes an exchange proxy meta transaction.
                                struct MetaTransactionData {
                                    // Signer of meta-transaction. On whose behalf to execute the MTX.
                                    address payable signer;
                                    // Required sender, or NULL for anyone.
                                    address sender;
                                    // Minimum gas price.
                                    uint256 minGasPrice;
                                    // Maximum gas price.
                                    uint256 maxGasPrice;
                                    // MTX is invalid after this time.
                                    uint256 expirationTimeSeconds;
                                    // Nonce to make this MTX unique.
                                    uint256 salt;
                                    // Encoded call data to a function on the exchange proxy.
                                    bytes callData;
                                    // Amount of ETH to attach to the call.
                                    uint256 value;
                                    // ERC20 fee `signer` pays `sender`.
                                    IERC20Token feeToken;
                                    // ERC20 fee amount.
                                    uint256 feeAmount;
                                }
                                /// @dev Emitted whenever a meta-transaction is executed via
                                ///      `executeMetaTransaction()` or `executeMetaTransactions()`.
                                /// @param hash The meta-transaction hash.
                                /// @param selector The selector of the function being executed.
                                /// @param signer Who to execute the meta-transaction on behalf of.
                                /// @param sender Who executed the meta-transaction.
                                event MetaTransactionExecuted(bytes32 hash, bytes4 indexed selector, address signer, address sender);
                                /// @dev Execute a single meta-transaction.
                                /// @param mtx The meta-transaction.
                                /// @param signature The signature by `mtx.signer`.
                                /// @return returnResult The ABI-encoded result of the underlying call.
                                function executeMetaTransaction(
                                    MetaTransactionData calldata mtx,
                                    LibSignature.Signature calldata signature
                                ) external payable returns (bytes memory returnResult);
                                /// @dev Execute multiple meta-transactions.
                                /// @param mtxs The meta-transactions.
                                /// @param signatures The signature by each respective `mtx.signer`.
                                /// @return returnResults The ABI-encoded results of the underlying calls.
                                function batchExecuteMetaTransactions(
                                    MetaTransactionData[] calldata mtxs,
                                    LibSignature.Signature[] calldata signatures
                                ) external payable returns (bytes[] memory returnResults);
                                /// @dev Get the block at which a meta-transaction has been executed.
                                /// @param mtx The meta-transaction.
                                /// @return blockNumber The block height when the meta-transactioin was executed.
                                function getMetaTransactionExecutedBlock(
                                    MetaTransactionData calldata mtx
                                ) external view returns (uint256 blockNumber);
                                /// @dev Get the block at which a meta-transaction hash has been executed.
                                /// @param mtxHash The meta-transaction hash.
                                /// @return blockNumber The block height when the meta-transactioin was executed.
                                function getMetaTransactionHashExecutedBlock(bytes32 mtxHash) external view returns (uint256 blockNumber);
                                /// @dev Get the EIP712 hash of a meta-transaction.
                                /// @param mtx The meta-transaction.
                                /// @return mtxHash The EIP712 hash of `mtx`.
                                function getMetaTransactionHash(MetaTransactionData calldata mtx) external view returns (bytes32 mtxHash);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "../libs/LibSignature.sol";
                            /// @dev Meta-transactions feature.
                            interface IMetaTransactionsFeatureV2 {
                                /// @dev Describes an exchange proxy meta transaction.
                                struct MetaTransactionFeeData {
                                    // ERC20 fee recipient
                                    address recipient;
                                    // ERC20 fee amount
                                    uint256 amount;
                                }
                                struct MetaTransactionDataV2 {
                                    // Signer of meta-transaction. On whose behalf to execute the MTX.
                                    address payable signer;
                                    // Required sender, or NULL for anyone.
                                    address sender;
                                    // MTX is invalid after this time.
                                    uint256 expirationTimeSeconds;
                                    // Nonce to make this MTX unique.
                                    uint256 salt;
                                    // Encoded call data to a function on the exchange proxy.
                                    bytes callData;
                                    // ERC20 fee `signer` pays `sender`.
                                    IERC20Token feeToken;
                                    // ERC20 fees.
                                    MetaTransactionFeeData[] fees;
                                }
                                /// @dev Emitted whenever a meta-transaction is executed via
                                ///      `executeMetaTransaction()` or `executeMetaTransactions()`.
                                /// @param hash The EIP712 hash of the MetaTransactionDataV2 struct.
                                /// @param selector The selector of the function being executed.
                                /// @param signer Who to execute the meta-transaction on behalf of.
                                /// @param sender Who executed the meta-transaction.
                                event MetaTransactionExecuted(bytes32 hash, bytes4 indexed selector, address signer, address sender);
                                /// @dev Execute a single meta-transaction.
                                /// @param mtx The meta-transaction.
                                /// @param signature The signature by `mtx.signer`.
                                /// @return returnResult The ABI-encoded result of the underlying call.
                                function executeMetaTransactionV2(
                                    MetaTransactionDataV2 calldata mtx,
                                    LibSignature.Signature calldata signature
                                ) external returns (bytes memory returnResult);
                                /// @dev Execute multiple meta-transactions.
                                /// @param mtxs The meta-transactions.
                                /// @param signatures The signature by each respective `mtx.signer`.
                                /// @return returnResults The ABI-encoded results of the underlying calls.
                                function batchExecuteMetaTransactionsV2(
                                    MetaTransactionDataV2[] calldata mtxs,
                                    LibSignature.Signature[] calldata signatures
                                ) external returns (bytes[] memory returnResults);
                                /// @dev Get the block at which a meta-transaction has been executed.
                                /// @param mtx The meta-transaction.
                                /// @return blockNumber The block height when the meta-transactioin was executed.
                                function getMetaTransactionV2ExecutedBlock(
                                    MetaTransactionDataV2 calldata mtx
                                ) external view returns (uint256 blockNumber);
                                /// @dev Get the block at which a meta-transaction hash has been executed.
                                /// @param mtxHash The EIP712 hash of the MetaTransactionDataV2 struct.
                                /// @return blockNumber The block height when the meta-transactioin was executed.
                                function getMetaTransactionV2HashExecutedBlock(bytes32 mtxHash) external view returns (uint256 blockNumber);
                                /// @dev Get the EIP712 hash of a meta-transaction.
                                /// @param mtx The meta-transaction.
                                /// @return mtxHash The EIP712 hash of `mtx`.
                                function getMetaTransactionV2Hash(MetaTransactionDataV2 calldata mtx) external view returns (bytes32 mtxHash);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            /// @dev VIP uniswap fill functions.
                            interface IUniswapFeature {
                                /// @dev Efficiently sell directly to uniswap/sushiswap.
                                /// @param tokens Sell path.
                                /// @param sellAmount of `tokens[0]` Amount to sell.
                                /// @param minBuyAmount Minimum amount of `tokens[-1]` to buy.
                                /// @param isSushi Use sushiswap if true.
                                /// @return buyAmount Amount of `tokens[-1]` bought.
                                function sellToUniswap(
                                    IERC20Token[] calldata tokens,
                                    uint256 sellAmount,
                                    uint256 minBuyAmount,
                                    bool isSushi
                                ) external payable returns (uint256 buyAmount);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            /// @dev VIP uniswap v3 fill functions.
                            interface IUniswapV3Feature {
                                /// @dev Sell attached ETH directly against uniswap v3.
                                /// @param encodedPath Uniswap-encoded path, where the first token is WETH.
                                /// @param minBuyAmount Minimum amount of the last token in the path to buy.
                                /// @param recipient The recipient of the bought tokens. Can be zero for sender.
                                /// @return buyAmount Amount of the last token in the path bought.
                                function sellEthForTokenToUniswapV3(
                                    bytes memory encodedPath,
                                    uint256 minBuyAmount,
                                    address recipient
                                ) external payable returns (uint256 buyAmount);
                                /// @dev Sell a token for ETH directly against uniswap v3.
                                /// @param encodedPath Uniswap-encoded path, where the last token is WETH.
                                /// @param sellAmount amount of the first token in the path to sell.
                                /// @param minBuyAmount Minimum amount of ETH to buy.
                                /// @param recipient The recipient of the bought tokens. Can be zero for sender.
                                /// @return buyAmount Amount of ETH bought.
                                function sellTokenForEthToUniswapV3(
                                    bytes memory encodedPath,
                                    uint256 sellAmount,
                                    uint256 minBuyAmount,
                                    address payable recipient
                                ) external returns (uint256 buyAmount);
                                /// @dev Sell a token for another token directly against uniswap v3.
                                /// @param encodedPath Uniswap-encoded path.
                                /// @param sellAmount amount of the first token in the path to sell.
                                /// @param minBuyAmount Minimum amount of the last token in the path to buy.
                                /// @param recipient The recipient of the bought tokens. Can be zero for sender.
                                /// @return buyAmount Amount of the last token in the path bought.
                                function sellTokenForTokenToUniswapV3(
                                    bytes memory encodedPath,
                                    uint256 sellAmount,
                                    uint256 minBuyAmount,
                                    address recipient
                                ) external returns (uint256 buyAmount);
                                /// @dev Sell a token for another token directly against uniswap v3. Internal variant.
                                /// @param encodedPath Uniswap-encoded path.
                                /// @param sellAmount amount of the first token in the path to sell.
                                /// @param minBuyAmount Minimum amount of the last token in the path to buy.
                                /// @param recipient The recipient of the bought tokens. Can be zero for payer.
                                /// @param payer The address to pull the sold tokens from.
                                /// @return buyAmount Amount of the last token in the path bought.
                                function _sellTokenForTokenToUniswapV3(
                                    bytes memory encodedPath,
                                    uint256 sellAmount,
                                    uint256 minBuyAmount,
                                    address recipient,
                                    address payer
                                ) external returns (uint256 buyAmount);
                                /// @dev Sell a token for another token directly against uniswap v3.
                                ///      Private variant, uses tokens held by `address(this)`.
                                /// @param encodedPath Uniswap-encoded path.
                                /// @param sellAmount amount of the first token in the path to sell.
                                /// @param minBuyAmount Minimum amount of the last token in the path to buy.
                                /// @param recipient The recipient of the bought tokens. Can be zero for sender.
                                /// @return buyAmount Amount of the last token in the path bought.
                                function _sellHeldTokenForTokenToUniswapV3(
                                    bytes memory encodedPath,
                                    uint256 sellAmount,
                                    uint256 minBuyAmount,
                                    address recipient
                                ) external returns (uint256 buyAmount);
                                /// @dev The UniswapV3 pool swap callback which pays the funds requested
                                ///      by the caller/pool to the pool. Can only be called by a valid
                                ///      UniswapV3 pool.
                                /// @param amount0Delta Token0 amount owed.
                                /// @param amount1Delta Token1 amount owed.
                                /// @param data Arbitrary data forwarded from swap() caller. An ABI-encoded
                                ///        struct of: inputToken, outputToken, fee, payer
                                function uniswapV3SwapCallback(int256 amount0Delta, int256 amount1Delta, bytes calldata data) external;
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            /// @dev VIP PancakeSwap (and forks) fill functions.
                            interface IPancakeSwapFeature {
                                enum ProtocolFork {
                                    PancakeSwap,
                                    PancakeSwapV2,
                                    BakerySwap,
                                    SushiSwap,
                                    ApeSwap,
                                    CafeSwap,
                                    CheeseSwap,
                                    JulSwap
                                }
                                /// @dev Efficiently sell directly to PancakeSwap (and forks).
                                /// @param tokens Sell path.
                                /// @param sellAmount of `tokens[0]` Amount to sell.
                                /// @param minBuyAmount Minimum amount of `tokens[-1]` to buy.
                                /// @param fork The protocol fork to use.
                                /// @return buyAmount Amount of `tokens[-1]` bought.
                                function sellToPancakeSwap(
                                    IERC20Token[] calldata tokens,
                                    uint256 sellAmount,
                                    uint256 minBuyAmount,
                                    ProtocolFork fork
                                ) external payable returns (uint256 buyAmount);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "../../vendor/ILiquidityProvider.sol";
                            /// @dev Feature to swap directly with an on-chain liquidity provider.
                            interface ILiquidityProviderFeature {
                                /// @dev Event for data pipeline.
                                event LiquidityProviderSwap(
                                    IERC20Token inputToken,
                                    IERC20Token outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 outputTokenAmount,
                                    ILiquidityProvider provider,
                                    address recipient
                                );
                                /// @dev Sells `sellAmount` of `inputToken` to the liquidity provider
                                ///      at the given `provider` address.
                                /// @param inputToken The token being sold.
                                /// @param outputToken The token being bought.
                                /// @param provider The address of the on-chain liquidity provider
                                ///        to trade with.
                                /// @param recipient The recipient of the bought tokens. If equal to
                                ///        address(0), `msg.sender` is assumed to be the recipient.
                                /// @param sellAmount The amount of `inputToken` to sell.
                                /// @param minBuyAmount The minimum acceptable amount of `outputToken` to
                                ///        buy. Reverts if this amount is not satisfied.
                                /// @param auxiliaryData Auxiliary data supplied to the `provider` contract.
                                /// @return boughtAmount The amount of `outputToken` bought.
                                function sellToLiquidityProvider(
                                    IERC20Token inputToken,
                                    IERC20Token outputToken,
                                    ILiquidityProvider provider,
                                    address recipient,
                                    uint256 sellAmount,
                                    uint256 minBuyAmount,
                                    bytes calldata auxiliaryData
                                ) external payable returns (uint256 boughtAmount);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            interface ILiquidityProvider {
                                /// @dev An optional event an LP can emit for each fill against a source.
                                /// @param inputToken The input token.
                                /// @param outputToken The output token.
                                /// @param inputTokenAmount How much input token was sold.
                                /// @param outputTokenAmount How much output token was bought.
                                /// @param sourceId A bytes32 encoded ascii source ID. E.g., `bytes32('Curve')`/
                                /// @param sourceAddress An optional address associated with the source (e.g, a curve pool).
                                /// @param sourceId A bytes32 encoded ascii source ID. E.g., `bytes32('Curve')`/
                                /// @param sourceAddress An optional address associated with the source (e.g, a curve pool).
                                /// @param sender The caller of the LP.
                                /// @param recipient The recipient of the output tokens.
                                event LiquidityProviderFill(
                                    IERC20Token inputToken,
                                    IERC20Token outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 outputTokenAmount,
                                    bytes32 sourceId,
                                    address sourceAddress,
                                    address sender,
                                    address recipient
                                );
                                /// @dev Trades `inputToken` for `outputToken`. The amount of `inputToken`
                                ///      to sell must be transferred to the contract prior to calling this
                                ///      function to trigger the trade.
                                /// @param inputToken The token being sold.
                                /// @param outputToken The token being bought.
                                /// @param recipient The recipient of the bought tokens.
                                /// @param minBuyAmount The minimum acceptable amount of `outputToken` to buy.
                                /// @param auxiliaryData Arbitrary auxiliary data supplied to the contract.
                                /// @return boughtAmount The amount of `outputToken` bought.
                                function sellTokenForToken(
                                    IERC20Token inputToken,
                                    IERC20Token outputToken,
                                    address recipient,
                                    uint256 minBuyAmount,
                                    bytes calldata auxiliaryData
                                ) external returns (uint256 boughtAmount);
                                /// @dev Trades ETH for token. ETH must either be attached to this function
                                ///      call or sent to the contract prior to calling this function to
                                ///      trigger the trade.
                                /// @param outputToken The token being bought.
                                /// @param recipient The recipient of the bought tokens.
                                /// @param minBuyAmount The minimum acceptable amount of `outputToken` to buy.
                                /// @param auxiliaryData Arbitrary auxiliary data supplied to the contract.
                                /// @return boughtAmount The amount of `outputToken` bought.
                                function sellEthForToken(
                                    IERC20Token outputToken,
                                    address recipient,
                                    uint256 minBuyAmount,
                                    bytes calldata auxiliaryData
                                ) external payable returns (uint256 boughtAmount);
                                /// @dev Trades token for ETH. The token must be sent to the contract prior
                                ///      to calling this function to trigger the trade.
                                /// @param inputToken The token being sold.
                                /// @param recipient The recipient of the bought tokens.
                                /// @param minBuyAmount The minimum acceptable amount of ETH to buy.
                                /// @param auxiliaryData Arbitrary auxiliary data supplied to the contract.
                                /// @return boughtAmount The amount of ETH bought.
                                function sellTokenForEth(
                                    IERC20Token inputToken,
                                    address payable recipient,
                                    uint256 minBuyAmount,
                                    bytes calldata auxiliaryData
                                ) external returns (uint256 boughtAmount);
                                /// @dev Quotes the amount of `outputToken` that would be obtained by
                                ///      selling `sellAmount` of `inputToken`.
                                /// @param inputToken Address of the taker token (what to sell). Use
                                ///        the wETH address if selling ETH.
                                /// @param outputToken Address of the maker token (what to buy). Use
                                ///        the wETH address if buying ETH.
                                /// @param sellAmount Amount of `inputToken` to sell.
                                /// @return outputTokenAmount Amount of `outputToken` that would be obtained.
                                function getSellQuote(
                                    IERC20Token inputToken,
                                    IERC20Token outputToken,
                                    uint256 sellAmount
                                ) external view returns (uint256 outputTokenAmount);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../libs/LibNativeOrder.sol";
                            import "../libs/LibSignature.sol";
                            /// @dev Feature for batch/market filling limit and RFQ orders.
                            interface IBatchFillNativeOrdersFeature {
                                /// @dev Fills multiple limit orders.
                                /// @param orders Array of limit orders.
                                /// @param signatures Array of signatures corresponding to each order.
                                /// @param takerTokenFillAmounts Array of desired amounts to fill each order.
                                /// @param revertIfIncomplete If true, reverts if this function fails to
                                ///        fill the full fill amount for any individual order.
                                /// @return takerTokenFilledAmounts Array of amounts filled, in taker token.
                                /// @return makerTokenFilledAmounts Array of amounts filled, in maker token.
                                function batchFillLimitOrders(
                                    LibNativeOrder.LimitOrder[] calldata orders,
                                    LibSignature.Signature[] calldata signatures,
                                    uint128[] calldata takerTokenFillAmounts,
                                    bool revertIfIncomplete
                                ) external payable returns (uint128[] memory takerTokenFilledAmounts, uint128[] memory makerTokenFilledAmounts);
                                /// @dev Fills multiple RFQ orders.
                                /// @param orders Array of RFQ orders.
                                /// @param signatures Array of signatures corresponding to each order.
                                /// @param takerTokenFillAmounts Array of desired amounts to fill each order.
                                /// @param revertIfIncomplete If true, reverts if this function fails to
                                ///        fill the full fill amount for any individual order.
                                /// @return takerTokenFilledAmounts Array of amounts filled, in taker token.
                                /// @return makerTokenFilledAmounts Array of amounts filled, in maker token.
                                function batchFillRfqOrders(
                                    LibNativeOrder.RfqOrder[] calldata orders,
                                    LibSignature.Signature[] calldata signatures,
                                    uint128[] calldata takerTokenFillAmounts,
                                    bool revertIfIncomplete
                                ) external returns (uint128[] memory takerTokenFilledAmounts, uint128[] memory makerTokenFilledAmounts);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            interface IMultiplexFeature {
                                // Identifies the type of subcall.
                                enum MultiplexSubcall {
                                    Invalid,
                                    RFQ,
                                    OTC,
                                    UniswapV2,
                                    UniswapV3,
                                    LiquidityProvider,
                                    TransformERC20,
                                    BatchSell,
                                    MultiHopSell
                                }
                                // Parameters for a batch sell.
                                struct BatchSellParams {
                                    // The token being sold.
                                    IERC20Token inputToken;
                                    // The token being bought.
                                    IERC20Token outputToken;
                                    // The amount of `inputToken` to sell.
                                    uint256 sellAmount;
                                    // The nested calls to perform.
                                    BatchSellSubcall[] calls;
                                    // Whether to use the Exchange Proxy's balance
                                    // of input tokens.
                                    bool useSelfBalance;
                                    // The recipient of the bought output tokens.
                                    address recipient;
                                    // The sender of the input tokens.
                                    address payer;
                                }
                                // Represents a constituent call of a batch sell.
                                struct BatchSellSubcall {
                                    // The function to call.
                                    MultiplexSubcall id;
                                    // Amount of input token to sell. If the highest bit is 1,
                                    // this value represents a proportion of the total
                                    // `sellAmount` of the batch sell. See `_normalizeSellAmount`
                                    // for details.
                                    uint256 sellAmount;
                                    // ABI-encoded parameters needed to perform the call.
                                    bytes data;
                                }
                                // Parameters for a multi-hop sell.
                                struct MultiHopSellParams {
                                    // The sell path, i.e.
                                    // tokens = [inputToken, hopToken1, ..., hopTokenN, outputToken]
                                    address[] tokens;
                                    // The amount of `tokens[0]` to sell.
                                    uint256 sellAmount;
                                    // The nested calls to perform.
                                    MultiHopSellSubcall[] calls;
                                    // Whether to use the Exchange Proxy's balance
                                    // of input tokens.
                                    bool useSelfBalance;
                                    // The recipient of the bought output tokens.
                                    address recipient;
                                    // The sender of the input tokens.
                                    address payer;
                                }
                                // Represents a constituent call of a multi-hop sell.
                                struct MultiHopSellSubcall {
                                    // The function to call.
                                    MultiplexSubcall id;
                                    // ABI-encoded parameters needed to perform the call.
                                    bytes data;
                                }
                                struct BatchSellState {
                                    // Tracks the amount of input token sold.
                                    uint256 soldAmount;
                                    // Tracks the amount of output token bought.
                                    uint256 boughtAmount;
                                }
                                struct MultiHopSellState {
                                    // This variable is used for the input and output amounts of
                                    // each hop. After the final hop, this will contain the output
                                    // amount of the multi-hop sell.
                                    uint256 outputTokenAmount;
                                    // For each hop in a multi-hop sell, `from` is the
                                    // address that holds the input tokens of the hop,
                                    // `to` is the address that receives the output tokens
                                    // of the hop.
                                    // See `_computeHopTarget` for details.
                                    address from;
                                    address to;
                                    // The index of the current hop in the multi-hop chain.
                                    uint256 hopIndex;
                                }
                                /// @dev Sells attached ETH for `outputToken` using the provided
                                ///      calls.
                                /// @param outputToken The token to buy.
                                /// @param calls The calls to use to sell the attached ETH.
                                /// @param minBuyAmount The minimum amount of `outputToken` that
                                ///        must be bought for this function to not revert.
                                /// @return boughtAmount The amount of `outputToken` bought.
                                function multiplexBatchSellEthForToken(
                                    IERC20Token outputToken,
                                    BatchSellSubcall[] calldata calls,
                                    uint256 minBuyAmount
                                ) external payable returns (uint256 boughtAmount);
                                /// @dev Sells `sellAmount` of the given `inputToken` for ETH
                                ///      using the provided calls.
                                /// @param inputToken The token to sell.
                                /// @param calls The calls to use to sell the input tokens.
                                /// @param sellAmount The amount of `inputToken` to sell.
                                /// @param minBuyAmount The minimum amount of ETH that
                                ///        must be bought for this function to not revert.
                                /// @return boughtAmount The amount of ETH bought.
                                function multiplexBatchSellTokenForEth(
                                    IERC20Token inputToken,
                                    BatchSellSubcall[] calldata calls,
                                    uint256 sellAmount,
                                    uint256 minBuyAmount
                                ) external returns (uint256 boughtAmount);
                                /// @dev Sells `sellAmount` of the given `inputToken` for
                                ///      `outputToken` using the provided calls.
                                /// @param inputToken The token to sell.
                                /// @param outputToken The token to buy.
                                /// @param calls The calls to use to sell the input tokens.
                                /// @param sellAmount The amount of `inputToken` to sell.
                                /// @param minBuyAmount The minimum amount of `outputToken`
                                ///        that must be bought for this function to not revert.
                                /// @return boughtAmount The amount of `outputToken` bought.
                                function multiplexBatchSellTokenForToken(
                                    IERC20Token inputToken,
                                    IERC20Token outputToken,
                                    BatchSellSubcall[] calldata calls,
                                    uint256 sellAmount,
                                    uint256 minBuyAmount
                                ) external returns (uint256 boughtAmount);
                                /// @dev Executes a multiplex BatchSell using the given
                                ///      parameters. Internal only.
                                /// @param params The parameters for the BatchSell.
                                /// @param minBuyAmount The minimum amount of `params.outputToken`
                                ///        that must be bought for this function to not revert.
                                /// @return boughtAmount The amount of `params.outputToken` bought.
                                function _multiplexBatchSell(
                                    BatchSellParams memory params,
                                    uint256 minBuyAmount
                                ) external returns (uint256 boughtAmount);
                                /// @dev Sells attached ETH via the given sequence of tokens
                                ///      and calls. `tokens[0]` must be WETH.
                                ///      The last token in `tokens` is the output token that
                                ///      will ultimately be sent to `msg.sender`
                                /// @param tokens The sequence of tokens to use for the sell,
                                ///        i.e. `tokens[i]` will be sold for `tokens[i+1]` via
                                ///        `calls[i]`.
                                /// @param calls The sequence of calls to use for the sell.
                                /// @param minBuyAmount The minimum amount of output tokens that
                                ///        must be bought for this function to not revert.
                                /// @return boughtAmount The amount of output tokens bought.
                                function multiplexMultiHopSellEthForToken(
                                    address[] calldata tokens,
                                    MultiHopSellSubcall[] calldata calls,
                                    uint256 minBuyAmount
                                ) external payable returns (uint256 boughtAmount);
                                /// @dev Sells `sellAmount` of the input token (`tokens[0]`)
                                ///      for ETH via the given sequence of tokens and calls.
                                ///      The last token in `tokens` must be WETH.
                                /// @param tokens The sequence of tokens to use for the sell,
                                ///        i.e. `tokens[i]` will be sold for `tokens[i+1]` via
                                ///        `calls[i]`.
                                /// @param calls The sequence of calls to use for the sell.
                                /// @param minBuyAmount The minimum amount of ETH that
                                ///        must be bought for this function to not revert.
                                /// @return boughtAmount The amount of ETH bought.
                                function multiplexMultiHopSellTokenForEth(
                                    address[] calldata tokens,
                                    MultiHopSellSubcall[] calldata calls,
                                    uint256 sellAmount,
                                    uint256 minBuyAmount
                                ) external returns (uint256 boughtAmount);
                                /// @dev Sells `sellAmount` of the input token (`tokens[0]`)
                                ///      via the given sequence of tokens and calls.
                                ///      The last token in `tokens` is the output token that
                                ///      will ultimately be sent to `msg.sender`
                                /// @param tokens The sequence of tokens to use for the sell,
                                ///        i.e. `tokens[i]` will be sold for `tokens[i+1]` via
                                ///        `calls[i]`.
                                /// @param calls The sequence of calls to use for the sell.
                                /// @param minBuyAmount The minimum amount of output tokens that
                                ///        must be bought for this function to not revert.
                                /// @return boughtAmount The amount of output tokens bought.
                                function multiplexMultiHopSellTokenForToken(
                                    address[] calldata tokens,
                                    MultiHopSellSubcall[] calldata calls,
                                    uint256 sellAmount,
                                    uint256 minBuyAmount
                                ) external returns (uint256 boughtAmount);
                                /// @dev Executes a multiplex MultiHopSell using the given
                                ///      parameters. Internal only.
                                /// @param params The parameters for the MultiHopSell.
                                /// @param minBuyAmount The minimum amount of the output token
                                ///        that must be bought for this function to not revert.
                                /// @return boughtAmount The amount of the output token bought.
                                function _multiplexMultiHopSell(
                                    MultiHopSellParams memory params,
                                    uint256 minBuyAmount
                                ) external returns (uint256 boughtAmount);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "../libs/LibNativeOrder.sol";
                            import "../libs/LibSignature.sol";
                            /// @dev Feature for interacting with OTC orders.
                            interface IOtcOrdersFeature {
                                /// @dev Emitted whenever an `OtcOrder` is filled.
                                /// @param orderHash The canonical hash of the order.
                                /// @param maker The maker of the order.
                                /// @param taker The taker of the order.
                                /// @param makerTokenFilledAmount How much maker token was filled.
                                /// @param takerTokenFilledAmount How much taker token was filled.
                                event OtcOrderFilled(
                                    bytes32 orderHash,
                                    address maker,
                                    address taker,
                                    address makerToken,
                                    address takerToken,
                                    uint128 makerTokenFilledAmount,
                                    uint128 takerTokenFilledAmount
                                );
                                /// @dev Fill an OTC order for up to `takerTokenFillAmount` taker tokens.
                                /// @param order The OTC order.
                                /// @param makerSignature The order signature from the maker.
                                /// @param takerTokenFillAmount Maximum taker token amount to fill this
                                ///        order with.
                                /// @return takerTokenFilledAmount How much taker token was filled.
                                /// @return makerTokenFilledAmount How much maker token was filled.
                                function fillOtcOrder(
                                    LibNativeOrder.OtcOrder calldata order,
                                    LibSignature.Signature calldata makerSignature,
                                    uint128 takerTokenFillAmount
                                ) external returns (uint128 takerTokenFilledAmount, uint128 makerTokenFilledAmount);
                                /// @dev Fill an OTC order for up to `takerTokenFillAmount` taker tokens.
                                ///      Unwraps bought WETH into ETH before sending it to
                                ///      the taker.
                                /// @param order The OTC order.
                                /// @param makerSignature The order signature from the maker.
                                /// @param takerTokenFillAmount Maximum taker token amount to fill this
                                ///        order with.
                                /// @return takerTokenFilledAmount How much taker token was filled.
                                /// @return makerTokenFilledAmount How much maker token was filled.
                                function fillOtcOrderForEth(
                                    LibNativeOrder.OtcOrder calldata order,
                                    LibSignature.Signature calldata makerSignature,
                                    uint128 takerTokenFillAmount
                                ) external returns (uint128 takerTokenFilledAmount, uint128 makerTokenFilledAmount);
                                /// @dev Fill an OTC order whose taker token is WETH for up
                                ///      to `msg.value`.
                                /// @param order The OTC order.
                                /// @param makerSignature The order signature from the maker.
                                /// @return takerTokenFilledAmount How much taker token was filled.
                                /// @return makerTokenFilledAmount How much maker token was filled.
                                function fillOtcOrderWithEth(
                                    LibNativeOrder.OtcOrder calldata order,
                                    LibSignature.Signature calldata makerSignature
                                ) external payable returns (uint128 takerTokenFilledAmount, uint128 makerTokenFilledAmount);
                                /// @dev Fully fill an OTC order. "Meta-transaction" variant,
                                ///      requires order to be signed by both maker and taker.
                                /// @param order The OTC order.
                                /// @param makerSignature The order signature from the maker.
                                /// @param takerSignature The order signature from the taker.
                                function fillTakerSignedOtcOrder(
                                    LibNativeOrder.OtcOrder calldata order,
                                    LibSignature.Signature calldata makerSignature,
                                    LibSignature.Signature calldata takerSignature
                                ) external;
                                /// @dev Fully fill an OTC order. "Meta-transaction" variant,
                                ///      requires order to be signed by both maker and taker.
                                ///      Unwraps bought WETH into ETH before sending it to
                                ///      the taker.
                                /// @param order The OTC order.
                                /// @param makerSignature The order signature from the maker.
                                /// @param takerSignature The order signature from the taker.
                                function fillTakerSignedOtcOrderForEth(
                                    LibNativeOrder.OtcOrder calldata order,
                                    LibSignature.Signature calldata makerSignature,
                                    LibSignature.Signature calldata takerSignature
                                ) external;
                                /// @dev Fills multiple taker-signed OTC orders.
                                /// @param orders Array of OTC orders.
                                /// @param makerSignatures Array of maker signatures for each order.
                                /// @param takerSignatures Array of taker signatures for each order.
                                /// @param unwrapWeth Array of booleans representing whether or not
                                ///        to unwrap bought WETH into ETH for each order. Should be set
                                ///        to false if the maker token is not WETH.
                                /// @return successes Array of booleans representing whether or not
                                ///         each order in `orders` was filled successfully.
                                function batchFillTakerSignedOtcOrders(
                                    LibNativeOrder.OtcOrder[] calldata orders,
                                    LibSignature.Signature[] calldata makerSignatures,
                                    LibSignature.Signature[] calldata takerSignatures,
                                    bool[] calldata unwrapWeth
                                ) external returns (bool[] memory successes);
                                /// @dev Fill an OTC order for up to `takerTokenFillAmount` taker tokens.
                                ///      Internal variant.
                                /// @param order The OTC order.
                                /// @param makerSignature The order signature from the maker.
                                /// @param takerTokenFillAmount Maximum taker token amount to fill this
                                ///        order with.
                                /// @param taker The address to fill the order in the context of.
                                /// @param useSelfBalance Whether to use the Exchange Proxy's balance
                                ///        of input tokens.
                                /// @param recipient The recipient of the bought maker tokens.
                                /// @return takerTokenFilledAmount How much taker token was filled.
                                /// @return makerTokenFilledAmount How much maker token was filled.
                                function _fillOtcOrder(
                                    LibNativeOrder.OtcOrder calldata order,
                                    LibSignature.Signature calldata makerSignature,
                                    uint128 takerTokenFillAmount,
                                    address taker,
                                    bool useSelfBalance,
                                    address recipient
                                ) external returns (uint128 takerTokenFilledAmount, uint128 makerTokenFilledAmount);
                                /// @dev Get the order info for an OTC order.
                                /// @param order The OTC order.
                                /// @return orderInfo Info about the order.
                                function getOtcOrderInfo(
                                    LibNativeOrder.OtcOrder calldata order
                                ) external view returns (LibNativeOrder.OtcOrderInfo memory orderInfo);
                                /// @dev Get the canonical hash of an OTC order.
                                /// @param order The OTC order.
                                /// @return orderHash The order hash.
                                function getOtcOrderHash(LibNativeOrder.OtcOrder calldata order) external view returns (bytes32 orderHash);
                                /// @dev Get the last nonce used for a particular
                                ///      tx.origin address and nonce bucket.
                                /// @param txOrigin The address.
                                /// @param nonceBucket The nonce bucket index.
                                /// @return lastNonce The last nonce value used.
                                function lastOtcTxOriginNonce(address txOrigin, uint64 nonceBucket) external view returns (uint128 lastNonce);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            /// @dev Exchange Proxy Recovery Functions
                            interface IFundRecoveryFeature {
                                /// @dev calledFrom FundRecoveryFeature.transferTrappedTokensTo() This will be delegatecalled
                                /// in the context of the Exchange Proxy instance being used.
                                /// @param erc20 ERC20 Token Address.
                                /// @param amountOut Amount of tokens to withdraw.
                                /// @param recipientWallet Recipient wallet address.
                                function transferTrappedTokensTo(IERC20Token erc20, uint256 amountOut, address payable recipientWallet) external;
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "../libs/LibNFTOrder.sol";
                            import "../libs/LibSignature.sol";
                            import "../../vendor/IERC721Token.sol";
                            /// @dev Feature for interacting with ERC721 orders.
                            interface IERC721OrdersFeature {
                                /// @dev Emitted whenever an `ERC721Order` is filled.
                                /// @param direction Whether the order is selling or
                                ///        buying the ERC721 token.
                                /// @param maker The maker of the order.
                                /// @param taker The taker of the order.
                                /// @param nonce The unique maker nonce in the order.
                                /// @param erc20Token The address of the ERC20 token.
                                /// @param erc20TokenAmount The amount of ERC20 token
                                ///        to sell or buy.
                                /// @param erc721Token The address of the ERC721 token.
                                /// @param erc721TokenId The ID of the ERC721 asset.
                                /// @param matcher If this order was matched with another using `matchERC721Orders()`,
                                ///                this will be the address of the caller. If not, this will be `address(0)`.
                                event ERC721OrderFilled(
                                    LibNFTOrder.TradeDirection direction,
                                    address maker,
                                    address taker,
                                    uint256 nonce,
                                    IERC20Token erc20Token,
                                    uint256 erc20TokenAmount,
                                    IERC721Token erc721Token,
                                    uint256 erc721TokenId,
                                    address matcher
                                );
                                /// @dev Emitted whenever an `ERC721Order` is cancelled.
                                /// @param maker The maker of the order.
                                /// @param nonce The nonce of the order that was cancelled.
                                event ERC721OrderCancelled(address maker, uint256 nonce);
                                /// @dev Emitted when an `ERC721Order` is pre-signed.
                                ///      Contains all the fields of the order.
                                event ERC721OrderPreSigned(
                                    LibNFTOrder.TradeDirection direction,
                                    address maker,
                                    address taker,
                                    uint256 expiry,
                                    uint256 nonce,
                                    IERC20Token erc20Token,
                                    uint256 erc20TokenAmount,
                                    LibNFTOrder.Fee[] fees,
                                    IERC721Token erc721Token,
                                    uint256 erc721TokenId,
                                    LibNFTOrder.Property[] erc721TokenProperties
                                );
                                /// @dev Sells an ERC721 asset to fill the given order.
                                /// @param buyOrder The ERC721 buy order.
                                /// @param signature The order signature from the maker.
                                /// @param erc721TokenId The ID of the ERC721 asset being
                                ///        sold. If the given order specifies properties,
                                ///        the asset must satisfy those properties. Otherwise,
                                ///        it must equal the tokenId in the order.
                                /// @param unwrapNativeToken If this parameter is true and the
                                ///        ERC20 token of the order is e.g. WETH, unwraps the
                                ///        token before transferring it to the taker.
                                /// @param callbackData If this parameter is non-zero, invokes
                                ///        `zeroExERC721OrderCallback` on `msg.sender` after
                                ///        the ERC20 tokens have been transferred to `msg.sender`
                                ///        but before transferring the ERC721 asset to the buyer.
                                function sellERC721(
                                    LibNFTOrder.ERC721Order calldata buyOrder,
                                    LibSignature.Signature calldata signature,
                                    uint256 erc721TokenId,
                                    bool unwrapNativeToken,
                                    bytes calldata callbackData
                                ) external;
                                /// @dev Buys an ERC721 asset by filling the given order.
                                /// @param sellOrder The ERC721 sell order.
                                /// @param signature The order signature.
                                /// @param callbackData If this parameter is non-zero, invokes
                                ///        `zeroExERC721OrderCallback` on `msg.sender` after
                                ///        the ERC721 asset has been transferred to `msg.sender`
                                ///        but before transferring the ERC20 tokens to the seller.
                                ///        Native tokens acquired during the callback can be used
                                ///        to fill the order.
                                function buyERC721(
                                    LibNFTOrder.ERC721Order calldata sellOrder,
                                    LibSignature.Signature calldata signature,
                                    bytes calldata callbackData
                                ) external payable;
                                /// @dev Cancel a single ERC721 order by its nonce. The caller
                                ///      should be the maker of the order. Silently succeeds if
                                ///      an order with the same nonce has already been filled or
                                ///      cancelled.
                                /// @param orderNonce The order nonce.
                                function cancelERC721Order(uint256 orderNonce) external;
                                /// @dev Cancel multiple ERC721 orders by their nonces. The caller
                                ///      should be the maker of the orders. Silently succeeds if
                                ///      an order with the same nonce has already been filled or
                                ///      cancelled.
                                /// @param orderNonces The order nonces.
                                function batchCancelERC721Orders(uint256[] calldata orderNonces) external;
                                /// @dev Buys multiple ERC721 assets by filling the
                                ///      given orders.
                                /// @param sellOrders The ERC721 sell orders.
                                /// @param signatures The order signatures.
                                /// @param callbackData The data (if any) to pass to the taker
                                ///        callback for each order. Refer to the `callbackData`
                                ///        parameter to for `buyERC721`.
                                /// @param revertIfIncomplete If true, reverts if this
                                ///        function fails to fill any individual order.
                                /// @return successes An array of booleans corresponding to whether
                                ///         each order in `orders` was successfully filled.
                                function batchBuyERC721s(
                                    LibNFTOrder.ERC721Order[] calldata sellOrders,
                                    LibSignature.Signature[] calldata signatures,
                                    bytes[] calldata callbackData,
                                    bool revertIfIncomplete
                                ) external payable returns (bool[] memory successes);
                                /// @dev Matches a pair of complementary orders that have
                                ///      a non-negative spread. Each order is filled at
                                ///      their respective price, and the matcher receives
                                ///      a profit denominated in the ERC20 token.
                                /// @param sellOrder Order selling an ERC721 asset.
                                /// @param buyOrder Order buying an ERC721 asset.
                                /// @param sellOrderSignature Signature for the sell order.
                                /// @param buyOrderSignature Signature for the buy order.
                                /// @return profit The amount of profit earned by the caller
                                ///         of this function (denominated in the ERC20 token
                                ///         of the matched orders).
                                function matchERC721Orders(
                                    LibNFTOrder.ERC721Order calldata sellOrder,
                                    LibNFTOrder.ERC721Order calldata buyOrder,
                                    LibSignature.Signature calldata sellOrderSignature,
                                    LibSignature.Signature calldata buyOrderSignature
                                ) external returns (uint256 profit);
                                /// @dev Matches pairs of complementary orders that have
                                ///      non-negative spreads. Each order is filled at
                                ///      their respective price, and the matcher receives
                                ///      a profit denominated in the ERC20 token.
                                /// @param sellOrders Orders selling ERC721 assets.
                                /// @param buyOrders Orders buying ERC721 assets.
                                /// @param sellOrderSignatures Signatures for the sell orders.
                                /// @param buyOrderSignatures Signatures for the buy orders.
                                /// @return profits The amount of profit earned by the caller
                                ///         of this function for each pair of matched orders
                                ///         (denominated in the ERC20 token of the order pair).
                                /// @return successes An array of booleans corresponding to
                                ///         whether each pair of orders was successfully matched.
                                function batchMatchERC721Orders(
                                    LibNFTOrder.ERC721Order[] calldata sellOrders,
                                    LibNFTOrder.ERC721Order[] calldata buyOrders,
                                    LibSignature.Signature[] calldata sellOrderSignatures,
                                    LibSignature.Signature[] calldata buyOrderSignatures
                                ) external returns (uint256[] memory profits, bool[] memory successes);
                                /// @dev Callback for the ERC721 `safeTransferFrom` function.
                                ///      This callback can be used to sell an ERC721 asset if
                                ///      a valid ERC721 order, signature and `unwrapNativeToken`
                                ///      are encoded in `data`. This allows takers to sell their
                                ///      ERC721 asset without first calling `setApprovalForAll`.
                                /// @param operator The address which called `safeTransferFrom`.
                                /// @param from The address which previously owned the token.
                                /// @param tokenId The ID of the asset being transferred.
                                /// @param data Additional data with no specified format. If a
                                ///        valid ERC721 order, signature and `unwrapNativeToken`
                                ///        are encoded in `data`, this function will try to fill
                                ///        the order using the received asset.
                                /// @return success The selector of this function (0x150b7a02),
                                ///         indicating that the callback succeeded.
                                function onERC721Received(
                                    address operator,
                                    address from,
                                    uint256 tokenId,
                                    bytes calldata data
                                ) external returns (bytes4 success);
                                /// @dev Approves an ERC721 order on-chain. After pre-signing
                                ///      the order, the `PRESIGNED` signature type will become
                                ///      valid for that order and signer.
                                /// @param order An ERC721 order.
                                function preSignERC721Order(LibNFTOrder.ERC721Order calldata order) external;
                                /// @dev Checks whether the given signature is valid for the
                                ///      the given ERC721 order. Reverts if not.
                                /// @param order The ERC721 order.
                                /// @param signature The signature to validate.
                                function validateERC721OrderSignature(
                                    LibNFTOrder.ERC721Order calldata order,
                                    LibSignature.Signature calldata signature
                                ) external view;
                                /// @dev If the given order is buying an ERC721 asset, checks
                                ///      whether or not the given token ID satisfies the required
                                ///      properties specified in the order. If the order does not
                                ///      specify any properties, this function instead checks
                                ///      whether the given token ID matches the ID in the order.
                                ///      Reverts if any checks fail, or if the order is selling
                                ///      an ERC721 asset.
                                /// @param order The ERC721 order.
                                /// @param erc721TokenId The ID of the ERC721 asset.
                                function validateERC721OrderProperties(LibNFTOrder.ERC721Order calldata order, uint256 erc721TokenId) external view;
                                /// @dev Get the current status of an ERC721 order.
                                /// @param order The ERC721 order.
                                /// @return status The status of the order.
                                function getERC721OrderStatus(
                                    LibNFTOrder.ERC721Order calldata order
                                ) external view returns (LibNFTOrder.OrderStatus status);
                                /// @dev Get the EIP-712 hash of an ERC721 order.
                                /// @param order The ERC721 order.
                                /// @return orderHash The order hash.
                                function getERC721OrderHash(LibNFTOrder.ERC721Order calldata order) external view returns (bytes32 orderHash);
                                /// @dev Get the order status bit vector for the given
                                ///      maker address and nonce range.
                                /// @param maker The maker of the order.
                                /// @param nonceRange Order status bit vectors are indexed
                                ///        by maker address and the upper 248 bits of the
                                ///        order nonce. We define `nonceRange` to be these
                                ///        248 bits.
                                /// @return bitVector The order status bit vector for the
                                ///         given maker and nonce range.
                                function getERC721OrderStatusBitVector(address maker, uint248 nonceRange) external view returns (uint256 bitVector);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "../../vendor/IERC1155Token.sol";
                            import "../../vendor/IERC721Token.sol";
                            import "../../vendor/IPropertyValidator.sol";
                            /// @dev A library for common NFT order operations.
                            library LibNFTOrder {
                                enum OrderStatus {
                                    INVALID,
                                    FILLABLE,
                                    UNFILLABLE,
                                    EXPIRED
                                }
                                enum TradeDirection {
                                    SELL_NFT,
                                    BUY_NFT
                                }
                                struct Property {
                                    IPropertyValidator propertyValidator;
                                    bytes propertyData;
                                }
                                struct Fee {
                                    address recipient;
                                    uint256 amount;
                                    bytes feeData;
                                }
                                // "Base struct" for ERC721Order and ERC1155, used
                                // by the abstract contract `NFTOrders`.
                                struct NFTOrder {
                                    TradeDirection direction;
                                    address maker;
                                    address taker;
                                    uint256 expiry;
                                    uint256 nonce;
                                    IERC20Token erc20Token;
                                    uint256 erc20TokenAmount;
                                    Fee[] fees;
                                    address nft;
                                    uint256 nftId;
                                    Property[] nftProperties;
                                }
                                // All fields align with those of NFTOrder
                                struct ERC721Order {
                                    TradeDirection direction;
                                    address maker;
                                    address taker;
                                    uint256 expiry;
                                    uint256 nonce;
                                    IERC20Token erc20Token;
                                    uint256 erc20TokenAmount;
                                    Fee[] fees;
                                    IERC721Token erc721Token;
                                    uint256 erc721TokenId;
                                    Property[] erc721TokenProperties;
                                }
                                // All fields except `erc1155TokenAmount` align
                                // with those of NFTOrder
                                struct ERC1155Order {
                                    TradeDirection direction;
                                    address maker;
                                    address taker;
                                    uint256 expiry;
                                    uint256 nonce;
                                    IERC20Token erc20Token;
                                    uint256 erc20TokenAmount;
                                    Fee[] fees;
                                    IERC1155Token erc1155Token;
                                    uint256 erc1155TokenId;
                                    Property[] erc1155TokenProperties;
                                    // End of fields shared with NFTOrder
                                    uint128 erc1155TokenAmount;
                                }
                                struct OrderInfo {
                                    bytes32 orderHash;
                                    OrderStatus status;
                                    // `orderAmount` is 1 for all ERC721Orders, and
                                    // `erc1155TokenAmount` for ERC1155Orders.
                                    uint128 orderAmount;
                                    // The remaining amount of the ERC721/ERC1155 asset
                                    // that can be filled for the order.
                                    uint128 remainingAmount;
                                }
                                // The type hash for ERC721 orders, which is:
                                // keccak256(abi.encodePacked(
                                //     "ERC721Order(",
                                //       "uint8 direction,",
                                //       "address maker,",
                                //       "address taker,",
                                //       "uint256 expiry,",
                                //       "uint256 nonce,",
                                //       "address erc20Token,",
                                //       "uint256 erc20TokenAmount,",
                                //       "Fee[] fees,",
                                //       "address erc721Token,",
                                //       "uint256 erc721TokenId,",
                                //       "Property[] erc721TokenProperties",
                                //     ")",
                                //     "Fee(",
                                //       "address recipient,",
                                //       "uint256 amount,",
                                //       "bytes feeData",
                                //     ")",
                                //     "Property(",
                                //       "address propertyValidator,",
                                //       "bytes propertyData",
                                //     ")"
                                // ))
                                uint256 private constant _ERC_721_ORDER_TYPEHASH =
                                    0x2de32b2b090da7d8ab83ca4c85ba2eb6957bc7f6c50cb4ae1995e87560d808ed;
                                // The type hash for ERC1155 orders, which is:
                                // keccak256(abi.encodePacked(
                                //     "ERC1155Order(",
                                //       "uint8 direction,",
                                //       "address maker,",
                                //       "address taker,",
                                //       "uint256 expiry,",
                                //       "uint256 nonce,",
                                //       "address erc20Token,",
                                //       "uint256 erc20TokenAmount,",
                                //       "Fee[] fees,",
                                //       "address erc1155Token,",
                                //       "uint256 erc1155TokenId,",
                                //       "Property[] erc1155TokenProperties,",
                                //       "uint128 erc1155TokenAmount",
                                //     ")",
                                //     "Fee(",
                                //       "address recipient,",
                                //       "uint256 amount,",
                                //       "bytes feeData",
                                //     ")",
                                //     "Property(",
                                //       "address propertyValidator,",
                                //       "bytes propertyData",
                                //     ")"
                                // ))
                                uint256 private constant _ERC_1155_ORDER_TYPEHASH =
                                    0x930490b1bcedd2e5139e22c761fafd52e533960197c2283f3922c7fd8c880be9;
                                // keccak256(abi.encodePacked(
                                //     "Fee(",
                                //       "address recipient,",
                                //       "uint256 amount,",
                                //       "bytes feeData",
                                //     ")"
                                // ))
                                uint256 private constant _FEE_TYPEHASH = 0xe68c29f1b4e8cce0bbcac76eb1334bdc1dc1f293a517c90e9e532340e1e94115;
                                // keccak256(abi.encodePacked(
                                //     "Property(",
                                //       "address propertyValidator,",
                                //       "bytes propertyData",
                                //     ")"
                                // ))
                                uint256 private constant _PROPERTY_TYPEHASH = 0x6292cf854241cb36887e639065eca63b3af9f7f70270cebeda4c29b6d3bc65e8;
                                // keccak256("");
                                bytes32 private constant _EMPTY_ARRAY_KECCAK256 =
                                    0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
                                // keccak256(abi.encodePacked(keccak256(abi.encode(
                                //     _PROPERTY_TYPEHASH,
                                //     address(0),
                                //     keccak256("")
                                // ))));
                                bytes32 private constant _NULL_PROPERTY_STRUCT_HASH =
                                    0x720ee400a9024f6a49768142c339bf09d2dd9056ab52d20fbe7165faba6e142d;
                                uint256 private constant ADDRESS_MASK = (1 << 160) - 1;
                                // ERC721Order and NFTOrder fields are aligned, so
                                // we can safely cast an ERC721Order to an NFTOrder.
                                function asNFTOrder(ERC721Order memory erc721Order) internal pure returns (NFTOrder memory nftOrder) {
                                    assembly {
                                        nftOrder := erc721Order
                                    }
                                }
                                // ERC1155Order and NFTOrder fields are aligned with
                                // the exception of the last field `erc1155TokenAmount`
                                // in ERC1155Order, so we can safely cast an ERC1155Order
                                // to an NFTOrder.
                                function asNFTOrder(ERC1155Order memory erc1155Order) internal pure returns (NFTOrder memory nftOrder) {
                                    assembly {
                                        nftOrder := erc1155Order
                                    }
                                }
                                // ERC721Order and NFTOrder fields are aligned, so
                                // we can safely cast an MFTOrder to an ERC721Order.
                                function asERC721Order(NFTOrder memory nftOrder) internal pure returns (ERC721Order memory erc721Order) {
                                    assembly {
                                        erc721Order := nftOrder
                                    }
                                }
                                // NOTE: This is only safe if `nftOrder` was previously
                                // cast from an `ERC1155Order` and the original
                                // `erc1155TokenAmount` memory word has not been corrupted!
                                function asERC1155Order(NFTOrder memory nftOrder) internal pure returns (ERC1155Order memory erc1155Order) {
                                    assembly {
                                        erc1155Order := nftOrder
                                    }
                                }
                                /// @dev Get the struct hash of an ERC721 order.
                                /// @param order The ERC721 order.
                                /// @return structHash The struct hash of the order.
                                function getERC721OrderStructHash(ERC721Order memory order) internal pure returns (bytes32 structHash) {
                                    bytes32 propertiesHash = _propertiesHash(order.erc721TokenProperties);
                                    bytes32 feesHash = _feesHash(order.fees);
                                    // Hash in place, equivalent to:
                                    // return keccak256(abi.encode(
                                    //     _ERC_721_ORDER_TYPEHASH,
                                    //     order.direction,
                                    //     order.maker,
                                    //     order.taker,
                                    //     order.expiry,
                                    //     order.nonce,
                                    //     order.erc20Token,
                                    //     order.erc20TokenAmount,
                                    //     feesHash,
                                    //     order.erc721Token,
                                    //     order.erc721TokenId,
                                    //     propertiesHash
                                    // ));
                                    assembly {
                                        if lt(order, 32) {
                                            invalid()
                                        } // Don't underflow memory.
                                        let typeHashPos := sub(order, 32) // order - 32
                                        let feesHashPos := add(order, 224) // order + (32 * 7)
                                        let propertiesHashPos := add(order, 320) // order + (32 * 10)
                                        let typeHashMemBefore := mload(typeHashPos)
                                        let feeHashMemBefore := mload(feesHashPos)
                                        let propertiesHashMemBefore := mload(propertiesHashPos)
                                        mstore(typeHashPos, _ERC_721_ORDER_TYPEHASH)
                                        mstore(feesHashPos, feesHash)
                                        mstore(propertiesHashPos, propertiesHash)
                                        structHash := keccak256(typeHashPos, 384 /* 32 * 12 */)
                                        mstore(typeHashPos, typeHashMemBefore)
                                        mstore(feesHashPos, feeHashMemBefore)
                                        mstore(propertiesHashPos, propertiesHashMemBefore)
                                    }
                                    return structHash;
                                }
                                /// @dev Get the struct hash of an ERC1155 order.
                                /// @param order The ERC1155 order.
                                /// @return structHash The struct hash of the order.
                                function getERC1155OrderStructHash(ERC1155Order memory order) internal pure returns (bytes32 structHash) {
                                    bytes32 propertiesHash = _propertiesHash(order.erc1155TokenProperties);
                                    bytes32 feesHash = _feesHash(order.fees);
                                    // Hash in place, equivalent to:
                                    // return keccak256(abi.encode(
                                    //     _ERC_1155_ORDER_TYPEHASH,
                                    //     order.direction,
                                    //     order.maker,
                                    //     order.taker,
                                    //     order.expiry,
                                    //     order.nonce,
                                    //     order.erc20Token,
                                    //     order.erc20TokenAmount,
                                    //     feesHash,
                                    //     order.erc1155Token,
                                    //     order.erc1155TokenId,
                                    //     propertiesHash,
                                    //     order.erc1155TokenAmount
                                    // ));
                                    assembly {
                                        if lt(order, 32) {
                                            invalid()
                                        } // Don't underflow memory.
                                        let typeHashPos := sub(order, 32) // order - 32
                                        let feesHashPos := add(order, 224) // order + (32 * 7)
                                        let propertiesHashPos := add(order, 320) // order + (32 * 10)
                                        let typeHashMemBefore := mload(typeHashPos)
                                        let feesHashMemBefore := mload(feesHashPos)
                                        let propertiesHashMemBefore := mload(propertiesHashPos)
                                        mstore(typeHashPos, _ERC_1155_ORDER_TYPEHASH)
                                        mstore(feesHashPos, feesHash)
                                        mstore(propertiesHashPos, propertiesHash)
                                        structHash := keccak256(typeHashPos, 416 /* 32 * 12 */)
                                        mstore(typeHashPos, typeHashMemBefore)
                                        mstore(feesHashPos, feesHashMemBefore)
                                        mstore(propertiesHashPos, propertiesHashMemBefore)
                                    }
                                    return structHash;
                                }
                                // Hashes the `properties` arrayB as part of computing the
                                // EIP-712 hash of an `ERC721Order` or `ERC1155Order`.
                                function _propertiesHash(Property[] memory properties) private pure returns (bytes32 propertiesHash) {
                                    uint256 numProperties = properties.length;
                                    // We give `properties.length == 0` and `properties.length == 1`
                                    // special treatment because we expect these to be the most common.
                                    if (numProperties == 0) {
                                        propertiesHash = _EMPTY_ARRAY_KECCAK256;
                                    } else if (numProperties == 1) {
                                        Property memory property = properties[0];
                                        if (address(property.propertyValidator) == address(0) && property.propertyData.length == 0) {
                                            propertiesHash = _NULL_PROPERTY_STRUCT_HASH;
                                        } else {
                                            // propertiesHash = keccak256(abi.encodePacked(keccak256(abi.encode(
                                            //     _PROPERTY_TYPEHASH,
                                            //     properties[0].propertyValidator,
                                            //     keccak256(properties[0].propertyData)
                                            // ))));
                                            bytes32 dataHash = keccak256(property.propertyData);
                                            assembly {
                                                // Load free memory pointer
                                                let mem := mload(64)
                                                mstore(mem, _PROPERTY_TYPEHASH)
                                                // property.propertyValidator
                                                mstore(add(mem, 32), and(ADDRESS_MASK, mload(property)))
                                                // keccak256(property.propertyData)
                                                mstore(add(mem, 64), dataHash)
                                                mstore(mem, keccak256(mem, 96))
                                                propertiesHash := keccak256(mem, 32)
                                            }
                                        }
                                    } else {
                                        bytes32[] memory propertyStructHashArray = new bytes32[](numProperties);
                                        for (uint256 i = 0; i < numProperties; i++) {
                                            propertyStructHashArray[i] = keccak256(
                                                abi.encode(
                                                    _PROPERTY_TYPEHASH,
                                                    properties[i].propertyValidator,
                                                    keccak256(properties[i].propertyData)
                                                )
                                            );
                                        }
                                        assembly {
                                            propertiesHash := keccak256(add(propertyStructHashArray, 32), mul(numProperties, 32))
                                        }
                                    }
                                }
                                // Hashes the `fees` arrayB as part of computing the
                                // EIP-712 hash of an `ERC721Order` or `ERC1155Order`.
                                function _feesHash(Fee[] memory fees) private pure returns (bytes32 feesHash) {
                                    uint256 numFees = fees.length;
                                    // We give `fees.length == 0` and `fees.length == 1`
                                    // special treatment because we expect these to be the most common.
                                    if (numFees == 0) {
                                        feesHash = _EMPTY_ARRAY_KECCAK256;
                                    } else if (numFees == 1) {
                                        // feesHash = keccak256(abi.encodePacked(keccak256(abi.encode(
                                        //     _FEE_TYPEHASH,
                                        //     fees[0].recipient,
                                        //     fees[0].amount,
                                        //     keccak256(fees[0].feeData)
                                        // ))));
                                        Fee memory fee = fees[0];
                                        bytes32 dataHash = keccak256(fee.feeData);
                                        assembly {
                                            // Load free memory pointer
                                            let mem := mload(64)
                                            mstore(mem, _FEE_TYPEHASH)
                                            // fee.recipient
                                            mstore(add(mem, 32), and(ADDRESS_MASK, mload(fee)))
                                            // fee.amount
                                            mstore(add(mem, 64), mload(add(fee, 32)))
                                            // keccak256(fee.feeData)
                                            mstore(add(mem, 96), dataHash)
                                            mstore(mem, keccak256(mem, 128))
                                            feesHash := keccak256(mem, 32)
                                        }
                                    } else {
                                        bytes32[] memory feeStructHashArray = new bytes32[](numFees);
                                        for (uint256 i = 0; i < numFees; i++) {
                                            feeStructHashArray[i] = keccak256(
                                                abi.encode(_FEE_TYPEHASH, fees[i].recipient, fees[i].amount, keccak256(fees[i].feeData))
                                            );
                                        }
                                        assembly {
                                            feesHash := keccak256(add(feeStructHashArray, 32), mul(numFees, 32))
                                        }
                                    }
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6;
                            pragma experimental ABIEncoderV2;
                            interface IERC1155Token {
                                /// @dev Either TransferSingle or TransferBatch MUST emit when tokens are transferred,
                                ///      including zero value transfers as well as minting or burning.
                                /// Operator will always be msg.sender.
                                /// Either event from address `0x0` signifies a minting operation.
                                /// An event to address `0x0` signifies a burning or melting operation.
                                /// The total value transferred from address 0x0 minus the total value transferred to 0x0 may
                                /// be used by clients and exchanges to be added to the "circulating supply" for a given token ID.
                                /// To define a token ID with no initial balance, the contract SHOULD emit the TransferSingle event
                                /// from `0x0` to `0x0`, with the token creator as `_operator`.
                                event TransferSingle(address indexed operator, address indexed from, address indexed to, uint256 id, uint256 value);
                                /// @dev Either TransferSingle or TransferBatch MUST emit when tokens are transferred,
                                ///      including zero value transfers as well as minting or burning.
                                ///Operator will always be msg.sender.
                                /// Either event from address `0x0` signifies a minting operation.
                                /// An event to address `0x0` signifies a burning or melting operation.
                                /// The total value transferred from address 0x0 minus the total value transferred to 0x0 may
                                /// be used by clients and exchanges to be added to the "circulating supply" for a given token ID.
                                /// To define multiple token IDs with no initial balance, this SHOULD emit the TransferBatch event
                                /// from `0x0` to `0x0`, with the token creator as `_operator`.
                                event TransferBatch(
                                    address indexed operator,
                                    address indexed from,
                                    address indexed to,
                                    uint256[] ids,
                                    uint256[] values
                                );
                                /// @dev MUST emit when an approval is updated.
                                event ApprovalForAll(address indexed owner, address indexed operator, bool approved);
                                /// @dev MUST emit when the URI is updated for a token ID.
                                /// URIs are defined in RFC 3986.
                                /// The URI MUST point a JSON file that conforms to the "ERC-1155 Metadata JSON Schema".
                                event URI(string value, uint256 indexed id);
                                /// @notice Transfers value amount of an _id from the _from address to the _to address specified.
                                /// @dev MUST emit TransferSingle event on success.
                                /// Caller must be approved to manage the _from account's tokens (see isApprovedForAll).
                                /// MUST throw if `_to` is the zero address.
                                /// MUST throw if balance of sender for token `_id` is lower than the `_value` sent.
                                /// MUST throw on any other error.
                                /// When transfer is complete, this function MUST check if `_to` is a smart contract (code size > 0).
                                /// If so, it MUST call `onERC1155Received` on `_to` and revert if the return value
                                /// is not `bytes4(keccak256("onERC1155Received(address,address,uint256,uint256,bytes)"))`.
                                /// @param from    Source address
                                /// @param to      Target address
                                /// @param id      ID of the token type
                                /// @param value   Transfer amount
                                /// @param data    Additional data with no specified format, sent in call to `_to`
                                function safeTransferFrom(address from, address to, uint256 id, uint256 value, bytes calldata data) external;
                                /// @notice Send multiple types of Tokens from a 3rd party in one transfer (with safety call).
                                /// @dev MUST emit TransferBatch event on success.
                                /// Caller must be approved to manage the _from account's tokens (see isApprovedForAll).
                                /// MUST throw if `_to` is the zero address.
                                /// MUST throw if length of `_ids` is not the same as length of `_values`.
                                ///  MUST throw if any of the balance of sender for token `_ids` is lower than the respective `_values` sent.
                                /// MUST throw on any other error.
                                /// When transfer is complete, this function MUST check if `_to` is a smart contract (code size > 0).
                                /// If so, it MUST call `onERC1155BatchReceived` on `_to` and revert if the return value
                                /// is not `bytes4(keccak256("onERC1155BatchReceived(address,address,uint256[],uint256[],bytes)"))`.
                                /// @param from    Source addresses
                                /// @param to      Target addresses
                                /// @param ids     IDs of each token type
                                /// @param values  Transfer amounts per token type
                                /// @param data    Additional data with no specified format, sent in call to `_to`
                                function safeBatchTransferFrom(
                                    address from,
                                    address to,
                                    uint256[] calldata ids,
                                    uint256[] calldata values,
                                    bytes calldata data
                                ) external;
                                /// @notice Enable or disable approval for a third party ("operator") to manage all of the caller's tokens.
                                /// @dev MUST emit the ApprovalForAll event on success.
                                /// @param operator  Address to add to the set of authorized operators
                                /// @param approved  True if the operator is approved, false to revoke approval
                                function setApprovalForAll(address operator, bool approved) external;
                                /// @notice Queries the approval status of an operator for a given owner.
                                /// @param owner        The owner of the Tokens
                                /// @param operator     Address of authorized operator
                                /// @return isApproved  True if the operator is approved, false if not
                                function isApprovedForAll(address owner, address operator) external view returns (bool isApproved);
                                /// @notice Get the balance of an account's Tokens.
                                /// @param owner     The address of the token holder
                                /// @param id        ID of the Token
                                /// @return balance  The _owner's balance of the Token type requested
                                function balanceOf(address owner, uint256 id) external view returns (uint256 balance);
                                /// @notice Get the balance of multiple account/token pairs
                                /// @param owners      The addresses of the token holders
                                /// @param ids         ID of the Tokens
                                /// @return balances_  The _owner's balance of the Token types requested
                                function balanceOfBatch(
                                    address[] calldata owners,
                                    uint256[] calldata ids
                                ) external view returns (uint256[] memory balances_);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6;
                            interface IERC721Token {
                                /// @dev This emits when ownership of any NFT changes by any mechanism.
                                ///      This event emits when NFTs are created (`from` == 0) and destroyed
                                ///      (`to` == 0). Exception: during contract creation, any number of NFTs
                                ///      may be created and assigned without emitting Transfer. At the time of
                                ///      any transfer, the approved address for that NFT (if any) is reset to none.
                                event Transfer(address indexed _from, address indexed _to, uint256 indexed _tokenId);
                                /// @dev This emits when the approved address for an NFT is changed or
                                ///      reaffirmed. The zero address indicates there is no approved address.
                                ///      When a Transfer event emits, this also indicates that the approved
                                ///      address for that NFT (if any) is reset to none.
                                event Approval(address indexed _owner, address indexed _approved, uint256 indexed _tokenId);
                                /// @dev This emits when an operator is enabled or disabled for an owner.
                                ///      The operator can manage all NFTs of the owner.
                                event ApprovalForAll(address indexed _owner, address indexed _operator, bool _approved);
                                /// @notice Transfers the ownership of an NFT from one address to another address
                                /// @dev Throws unless `msg.sender` is the current owner, an authorized
                                ///      perator, or the approved address for this NFT. Throws if `_from` is
                                ///      not the current owner. Throws if `_to` is the zero address. Throws if
                                ///      `_tokenId` is not a valid NFT. When transfer is complete, this function
                                ///      checks if `_to` is a smart contract (code size > 0). If so, it calls
                                ///      `onERC721Received` on `_to` and throws if the return value is not
                                ///      `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`.
                                /// @param _from The current owner of the NFT
                                /// @param _to The new owner
                                /// @param _tokenId The NFT to transfer
                                /// @param _data Additional data with no specified format, sent in call to `_to`
                                function safeTransferFrom(address _from, address _to, uint256 _tokenId, bytes calldata _data) external;
                                /// @notice Transfers the ownership of an NFT from one address to another address
                                /// @dev This works identically to the other function with an extra data parameter,
                                ///      except this function just sets data to "".
                                /// @param _from The current owner of the NFT
                                /// @param _to The new owner
                                /// @param _tokenId The NFT to transfer
                                function safeTransferFrom(address _from, address _to, uint256 _tokenId) external;
                                /// @notice Change or reaffirm the approved address for an NFT
                                /// @dev The zero address indicates there is no approved address.
                                ///      Throws unless `msg.sender` is the current NFT owner, or an authorized
                                ///      operator of the current owner.
                                /// @param _approved The new approved NFT controller
                                /// @param _tokenId The NFT to approve
                                function approve(address _approved, uint256 _tokenId) external;
                                /// @notice Enable or disable approval for a third party ("operator") to manage
                                ///         all of `msg.sender`'s assets
                                /// @dev Emits the ApprovalForAll event. The contract MUST allow
                                ///      multiple operators per owner.
                                /// @param _operator Address to add to the set of authorized operators
                                /// @param _approved True if the operator is approved, false to revoke approval
                                function setApprovalForAll(address _operator, bool _approved) external;
                                /// @notice Count all NFTs assigned to an owner
                                /// @dev NFTs assigned to the zero address are considered invalid, and this
                                ///      function throws for queries about the zero address.
                                /// @param _owner An address for whom to query the balance
                                /// @return The number of NFTs owned by `_owner`, possibly zero
                                function balanceOf(address _owner) external view returns (uint256);
                                /// @notice Transfer ownership of an NFT -- THE CALLER IS RESPONSIBLE
                                ///         TO CONFIRM THAT `_to` IS CAPABLE OF RECEIVING NFTS OR ELSE
                                ///         THEY MAY BE PERMANENTLY LOST
                                /// @dev Throws unless `msg.sender` is the current owner, an authorized
                                ///      operator, or the approved address for this NFT. Throws if `_from` is
                                ///      not the current owner. Throws if `_to` is the zero address. Throws if
                                ///      `_tokenId` is not a valid NFT.
                                /// @param _from The current owner of the NFT
                                /// @param _to The new owner
                                /// @param _tokenId The NFT to transfer
                                function transferFrom(address _from, address _to, uint256 _tokenId) external;
                                /// @notice Find the owner of an NFT
                                /// @dev NFTs assigned to zero address are considered invalid, and queries
                                ///      about them do throw.
                                /// @param _tokenId The identifier for an NFT
                                /// @return The address of the owner of the NFT
                                function ownerOf(uint256 _tokenId) external view returns (address);
                                /// @notice Get the approved address for a single NFT
                                /// @dev Throws if `_tokenId` is not a valid NFT.
                                /// @param _tokenId The NFT to find the approved address for
                                /// @return The approved address for this NFT, or the zero address if there is none
                                function getApproved(uint256 _tokenId) external view returns (address);
                                /// @notice Query if an address is an authorized operator for another address
                                /// @param _owner The address that owns the NFTs
                                /// @param _operator The address that acts on behalf of the owner
                                /// @return True if `_operator` is an approved operator for `_owner`, false otherwise
                                function isApprovedForAll(address _owner, address _operator) external view returns (bool);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6;
                            pragma experimental ABIEncoderV2;
                            interface IPropertyValidator {
                                /// @dev Checks that the given ERC721/ERC1155 asset satisfies the properties encoded in `propertyData`.
                                ///      Should revert if the asset does not satisfy the specified properties.
                                /// @param tokenAddress The ERC721/ERC1155 token contract address.
                                /// @param tokenId The ERC721/ERC1155 tokenId of the asset to check.
                                /// @param propertyData Encoded properties or auxiliary data needed to perform the check.
                                function validateProperty(address tokenAddress, uint256 tokenId, bytes calldata propertyData) external view;
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "../libs/LibNFTOrder.sol";
                            import "../libs/LibSignature.sol";
                            import "../../vendor/IERC1155Token.sol";
                            /// @dev Feature for interacting with ERC1155 orders.
                            interface IERC1155OrdersFeature {
                                /// @dev Emitted whenever an `ERC1155Order` is filled.
                                /// @param direction Whether the order is selling or
                                ///        buying the ERC1155 token.
                                /// @param maker The maker of the order.
                                /// @param taker The taker of the order.
                                /// @param nonce The unique maker nonce in the order.
                                /// @param erc20Token The address of the ERC20 token.
                                /// @param erc20FillAmount The amount of ERC20 token filled.
                                /// @param erc1155Token The address of the ERC1155 token.
                                /// @param erc1155TokenId The ID of the ERC1155 asset.
                                /// @param erc1155FillAmount The amount of ERC1155 asset filled.
                                /// @param matcher Currently unused.
                                event ERC1155OrderFilled(
                                    LibNFTOrder.TradeDirection direction,
                                    address maker,
                                    address taker,
                                    uint256 nonce,
                                    IERC20Token erc20Token,
                                    uint256 erc20FillAmount,
                                    IERC1155Token erc1155Token,
                                    uint256 erc1155TokenId,
                                    uint128 erc1155FillAmount,
                                    address matcher
                                );
                                /// @dev Emitted whenever an `ERC1155Order` is cancelled.
                                /// @param maker The maker of the order.
                                /// @param nonce The nonce of the order that was cancelled.
                                event ERC1155OrderCancelled(address maker, uint256 nonce);
                                /// @dev Emitted when an `ERC1155Order` is pre-signed.
                                ///      Contains all the fields of the order.
                                event ERC1155OrderPreSigned(
                                    LibNFTOrder.TradeDirection direction,
                                    address maker,
                                    address taker,
                                    uint256 expiry,
                                    uint256 nonce,
                                    IERC20Token erc20Token,
                                    uint256 erc20TokenAmount,
                                    LibNFTOrder.Fee[] fees,
                                    IERC1155Token erc1155Token,
                                    uint256 erc1155TokenId,
                                    LibNFTOrder.Property[] erc1155TokenProperties,
                                    uint128 erc1155TokenAmount
                                );
                                /// @dev Sells an ERC1155 asset to fill the given order.
                                /// @param buyOrder The ERC1155 buy order.
                                /// @param signature The order signature from the maker.
                                /// @param erc1155TokenId The ID of the ERC1155 asset being
                                ///        sold. If the given order specifies properties,
                                ///        the asset must satisfy those properties. Otherwise,
                                ///        it must equal the tokenId in the order.
                                /// @param erc1155SellAmount The amount of the ERC1155 asset
                                ///        to sell.
                                /// @param unwrapNativeToken If this parameter is true and the
                                ///        ERC20 token of the order is e.g. WETH, unwraps the
                                ///        token before transferring it to the taker.
                                /// @param callbackData If this parameter is non-zero, invokes
                                ///        `zeroExERC1155OrderCallback` on `msg.sender` after
                                ///        the ERC20 tokens have been transferred to `msg.sender`
                                ///        but before transferring the ERC1155 asset to the buyer.
                                function sellERC1155(
                                    LibNFTOrder.ERC1155Order calldata buyOrder,
                                    LibSignature.Signature calldata signature,
                                    uint256 erc1155TokenId,
                                    uint128 erc1155SellAmount,
                                    bool unwrapNativeToken,
                                    bytes calldata callbackData
                                ) external;
                                /// @dev Buys an ERC1155 asset by filling the given order.
                                /// @param sellOrder The ERC1155 sell order.
                                /// @param signature The order signature.
                                /// @param erc1155BuyAmount The amount of the ERC1155 asset
                                ///        to buy.
                                /// @param callbackData If this parameter is non-zero, invokes
                                ///        `zeroExERC1155OrderCallback` on `msg.sender` after
                                ///        the ERC1155 asset has been transferred to `msg.sender`
                                ///        but before transferring the ERC20 tokens to the seller.
                                ///        Native tokens acquired during the callback can be used
                                ///        to fill the order.
                                function buyERC1155(
                                    LibNFTOrder.ERC1155Order calldata sellOrder,
                                    LibSignature.Signature calldata signature,
                                    uint128 erc1155BuyAmount,
                                    bytes calldata callbackData
                                ) external payable;
                                /// @dev Cancel a single ERC1155 order by its nonce. The caller
                                ///      should be the maker of the order. Silently succeeds if
                                ///      an order with the same nonce has already been filled or
                                ///      cancelled.
                                /// @param orderNonce The order nonce.
                                function cancelERC1155Order(uint256 orderNonce) external;
                                /// @dev Cancel multiple ERC1155 orders by their nonces. The caller
                                ///      should be the maker of the orders. Silently succeeds if
                                ///      an order with the same nonce has already been filled or
                                ///      cancelled.
                                /// @param orderNonces The order nonces.
                                function batchCancelERC1155Orders(uint256[] calldata orderNonces) external;
                                /// @dev Buys multiple ERC1155 assets by filling the
                                ///      given orders.
                                /// @param sellOrders The ERC1155 sell orders.
                                /// @param signatures The order signatures.
                                /// @param erc1155TokenAmounts The amounts of the ERC1155 assets
                                ///        to buy for each order.
                                /// @param callbackData The data (if any) to pass to the taker
                                ///        callback for each order. Refer to the `callbackData`
                                ///        parameter to for `buyERC1155`.
                                /// @param revertIfIncomplete If true, reverts if this
                                ///        function fails to fill any individual order.
                                /// @return successes An array of booleans corresponding to whether
                                ///         each order in `orders` was successfully filled.
                                function batchBuyERC1155s(
                                    LibNFTOrder.ERC1155Order[] calldata sellOrders,
                                    LibSignature.Signature[] calldata signatures,
                                    uint128[] calldata erc1155TokenAmounts,
                                    bytes[] calldata callbackData,
                                    bool revertIfIncomplete
                                ) external payable returns (bool[] memory successes);
                                /// @dev Callback for the ERC1155 `safeTransferFrom` function.
                                ///      This callback can be used to sell an ERC1155 asset if
                                ///      a valid ERC1155 order, signature and `unwrapNativeToken`
                                ///      are encoded in `data`. This allows takers to sell their
                                ///      ERC1155 asset without first calling `setApprovalForAll`.
                                /// @param operator The address which called `safeTransferFrom`.
                                /// @param from The address which previously owned the token.
                                /// @param tokenId The ID of the asset being transferred.
                                /// @param value The amount being transferred.
                                /// @param data Additional data with no specified format. If a
                                ///        valid ERC1155 order, signature and `unwrapNativeToken`
                                ///        are encoded in `data`, this function will try to fill
                                ///        the order using the received asset.
                                /// @return success The selector of this function (0xf23a6e61),
                                ///         indicating that the callback succeeded.
                                function onERC1155Received(
                                    address operator,
                                    address from,
                                    uint256 tokenId,
                                    uint256 value,
                                    bytes calldata data
                                ) external returns (bytes4 success);
                                /// @dev Approves an ERC1155 order on-chain. After pre-signing
                                ///      the order, the `PRESIGNED` signature type will become
                                ///      valid for that order and signer.
                                /// @param order An ERC1155 order.
                                function preSignERC1155Order(LibNFTOrder.ERC1155Order calldata order) external;
                                /// @dev Checks whether the given signature is valid for the
                                ///      the given ERC1155 order. Reverts if not.
                                /// @param order The ERC1155 order.
                                /// @param signature The signature to validate.
                                function validateERC1155OrderSignature(
                                    LibNFTOrder.ERC1155Order calldata order,
                                    LibSignature.Signature calldata signature
                                ) external view;
                                /// @dev If the given order is buying an ERC1155 asset, checks
                                ///      whether or not the given token ID satisfies the required
                                ///      properties specified in the order. If the order does not
                                ///      specify any properties, this function instead checks
                                ///      whether the given token ID matches the ID in the order.
                                ///      Reverts if any checks fail, or if the order is selling
                                ///      an ERC1155 asset.
                                /// @param order The ERC1155 order.
                                /// @param erc1155TokenId The ID of the ERC1155 asset.
                                function validateERC1155OrderProperties(
                                    LibNFTOrder.ERC1155Order calldata order,
                                    uint256 erc1155TokenId
                                ) external view;
                                /// @dev Get the order info for an ERC1155 order.
                                /// @param order The ERC1155 order.
                                /// @return orderInfo Infor about the order.
                                function getERC1155OrderInfo(
                                    LibNFTOrder.ERC1155Order calldata order
                                ) external view returns (LibNFTOrder.OrderInfo memory orderInfo);
                                /// @dev Get the EIP-712 hash of an ERC1155 order.
                                /// @param order The ERC1155 order.
                                /// @return orderHash The order hash.
                                function getERC1155OrderHash(LibNFTOrder.ERC1155Order calldata order) external view returns (bytes32 orderHash);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6;
                            pragma experimental ABIEncoderV2;
                            /// @dev Implements the ERC165 `supportsInterface` function
                            interface IERC165Feature {
                                /// @dev Indicates whether the 0x Exchange Proxy implements a particular
                                ///      ERC165 interface. This function should use at most 30,000 gas.
                                /// @param interfaceId The interface identifier, as specified in ERC165.
                                /// @return isSupported Whether the given interface is supported by the
                                ///         0x Exchange Proxy.
                                function supportInterface(bytes4 interfaceId) external pure returns (bool isSupported);
                            }
                            

                            File 7 of 9: EthereumBridgeAdapter
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "./AbstractBridgeAdapter.sol";
                            import "./BridgeProtocols.sol";
                            import "./mixins/MixinAaveV2.sol";
                            import "./mixins/MixinBalancer.sol";
                            import "./mixins/MixinBalancerV2Batch.sol";
                            import "./mixins/MixinBancorV3.sol";
                            import "./mixins/MixinBarter.sol";
                            import "./mixins/MixinCompound.sol";
                            import "./mixins/MixinCurve.sol";
                            import "./mixins/MixinCurveV2.sol";
                            import "./mixins/MixinCryptoCom.sol";
                            import "./mixins/MixinDodo.sol";
                            import "./mixins/MixinDodoV2.sol";
                            import "./mixins/MixinKyberDmm.sol";
                            import "./mixins/MixinKyberElastic.sol";
                            import "./mixins/MixinLido.sol";
                            import "./mixins/MixinMakerPSM.sol";
                            import "./mixins/MixinMaverickV1.sol";
                            import "./mixins/MixinNerve.sol";
                            import "./mixins/MixinSynthetix.sol";
                            import "./mixins/MixinUniswap.sol";
                            import "./mixins/MixinUniswapV2.sol";
                            import "./mixins/MixinUniswapV3.sol";
                            import "./mixins/MixinZeroExBridge.sol";
                            contract EthereumBridgeAdapter is
                                AbstractBridgeAdapter(1, "Ethereum"),
                                MixinAaveV2,
                                MixinBalancer,
                                MixinBalancerV2Batch,
                                MixinBancorV3,
                                MixinBarter,
                                MixinCompound,
                                MixinCurve,
                                MixinCurveV2,
                                MixinCryptoCom,
                                MixinDodo,
                                MixinDodoV2,
                                MixinKyberDmm,
                                MixinKyberElastic,
                                MixinLido,
                                MixinMakerPSM,
                                MixinMaverickV1,
                                MixinNerve,
                                MixinSynthetix,
                                MixinUniswap,
                                MixinUniswapV2,
                                MixinUniswapV3,
                                MixinZeroExBridge
                            {
                                constructor(
                                    IEtherToken weth
                                ) public MixinBancorV3(weth) MixinCompound(weth) MixinCurve(weth) MixinLido(weth) MixinUniswap(weth) {}
                                function _trade(
                                    BridgeOrder memory order,
                                    IERC20Token sellToken,
                                    IERC20Token buyToken,
                                    uint256 sellAmount,
                                    bool dryRun
                                ) internal override returns (uint256 boughtAmount, bool supportedSource) {
                                    uint128 protocolId = uint128(uint256(order.source) >> 128);
                                    if (protocolId == BridgeProtocols.CURVE) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeCurve(sellToken, buyToken, sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.CURVEV2) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeCurveV2(sellToken, buyToken, sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.UNISWAPV3) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeUniswapV3(sellToken, sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.UNISWAPV2) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeUniswapV2(buyToken, sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.UNISWAP) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeUniswap(sellToken, buyToken, sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.BALANCER) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeBalancer(sellToken, buyToken, sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.BALANCERV2BATCH) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeBalancerV2Batch(sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.MAKERPSM) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeMakerPsm(sellToken, buyToken, sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.DODO) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeDodo(sellToken, sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.DODOV2) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeDodoV2(sellToken, sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.CRYPTOCOM) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeCryptoCom(buyToken, sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.NERVE) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeNerve(sellToken, sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.KYBERDMM) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeKyberDmm(buyToken, sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.KYBERELASTIC) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeKyberElastic(sellToken, sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.LIDO) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeLido(sellToken, buyToken, sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.AAVEV2) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeAaveV2(sellToken, buyToken, sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.COMPOUND) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeCompound(sellToken, buyToken, sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.BANCORV3) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeBancorV3(buyToken, sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.SYNTHETIX) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeSynthetix(sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.BARTER) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeBarter(sellToken, sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.MAVERICK) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeMaverickV1(sellToken, buyToken, sellAmount, order.bridgeData);
                                    } else if (protocolId == BridgeProtocols.UNKNOWN) {
                                        if (dryRun) {
                                            return (0, true);
                                        }
                                        boughtAmount = _tradeZeroExBridge(sellToken, buyToken, sellAmount, order.bridgeData);
                                    }
                                    emit BridgeFill(order.source, sellToken, buyToken, sellAmount, boughtAmount);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6;
                            pragma experimental ABIEncoderV2;
                            import "./IBridgeAdapter.sol";
                            abstract contract AbstractBridgeAdapter is IBridgeAdapter {
                                constructor(uint256 expectedChainId, string memory expectedChainName) public {
                                    uint256 chainId;
                                    assembly {
                                        chainId := chainid()
                                    }
                                    // Skip chain id validation on Ganache (1337), Anvil (31337), Goerli (5), Mumbai (80001), Base Goerli (84531)
                                    bool skipValidation = (chainId == 1337 ||
                                        chainId == 31337 ||
                                        chainId == 5 ||
                                        chainId == 80001 ||
                                        chainId == 84531);
                                    if (chainId != expectedChainId && !skipValidation) {
                                        revert(string(abi.encodePacked(expectedChainName, "BridgeAdapter.constructor: wrong chain ID")));
                                    }
                                }
                                function isSupportedSource(bytes32 source) external override returns (bool isSupported) {
                                    BridgeOrder memory placeholderOrder;
                                    placeholderOrder.source = source;
                                    IERC20Token placeholderToken = IERC20Token(address(0));
                                    (, isSupported) = _trade(placeholderOrder, placeholderToken, placeholderToken, 0, true);
                                }
                                function trade(
                                    BridgeOrder memory order,
                                    IERC20Token sellToken,
                                    IERC20Token buyToken,
                                    uint256 sellAmount
                                ) public override returns (uint256 boughtAmount) {
                                    (boughtAmount, ) = _trade(order, sellToken, buyToken, sellAmount, false);
                                }
                                function _trade(
                                    BridgeOrder memory order,
                                    IERC20Token sellToken,
                                    IERC20Token buyToken,
                                    uint256 sellAmount,
                                    bool dryRun
                                ) internal virtual returns (uint256 boughtAmount, bool supportedSource);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            interface IBridgeAdapter {
                                struct BridgeOrder {
                                    // Upper 16 bytes: uint128 protocol ID (right-aligned)
                                    // Lower 16 bytes: ASCII source name (left-aligned)
                                    bytes32 source;
                                    uint256 takerTokenAmount;
                                    uint256 makerTokenAmount;
                                    bytes bridgeData;
                                }
                                /// @dev Emitted when tokens are swapped with an external source.
                                /// @param source A unique ID for the source, where the upper 16 bytes
                                ///        encodes the (right-aligned) uint128 protocol ID and the
                                ///        lower 16 bytes encodes an ASCII source name.
                                /// @param inputToken The token the bridge is converting from.
                                /// @param outputToken The token the bridge is converting to.
                                /// @param inputTokenAmount Amount of input token sold.
                                /// @param outputTokenAmount Amount of output token bought.
                                event BridgeFill(
                                    bytes32 source,
                                    IERC20Token inputToken,
                                    IERC20Token outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 outputTokenAmount
                                );
                                function isSupportedSource(bytes32 source) external returns (bool isSupported);
                                function trade(
                                    BridgeOrder calldata order,
                                    IERC20Token sellToken,
                                    IERC20Token buyToken,
                                    uint256 sellAmount
                                ) external returns (uint256 boughtAmount);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity >=0.6.5 <0.9;
                            interface IERC20Token {
                                event Transfer(address indexed from, address indexed to, uint256 value);
                                event Approval(address indexed owner, address indexed spender, uint256 value);
                                /// @dev send `value` token to `to` from `msg.sender`
                                /// @param to The address of the recipient
                                /// @param value The amount of token to be transferred
                                /// @return True if transfer was successful
                                function transfer(address to, uint256 value) external returns (bool);
                                /// @dev send `value` token to `to` from `from` on the condition it is approved by `from`
                                /// @param from The address of the sender
                                /// @param to The address of the recipient
                                /// @param value The amount of token to be transferred
                                /// @return True if transfer was successful
                                function transferFrom(address from, address to, uint256 value) external returns (bool);
                                /// @dev `msg.sender` approves `spender` to spend `value` tokens
                                /// @param spender The address of the account able to transfer the tokens
                                /// @param value The amount of wei to be approved for transfer
                                /// @return Always true if the call has enough gas to complete execution
                                function approve(address spender, uint256 value) external returns (bool);
                                /// @dev Query total supply of token
                                /// @return Total supply of token
                                function totalSupply() external view returns (uint256);
                                /// @dev Get the balance of `owner`.
                                /// @param owner The address from which the balance will be retrieved
                                /// @return Balance of owner
                                function balanceOf(address owner) external view returns (uint256);
                                /// @dev Get the allowance for `spender` to spend from `owner`.
                                /// @param owner The address of the account owning tokens
                                /// @param spender The address of the account able to transfer the tokens
                                /// @return Amount of remaining tokens allowed to spent
                                function allowance(address owner, address spender) external view returns (uint256);
                                /// @dev Get the number of decimals this token has.
                                function decimals() external view returns (uint8);
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            library BridgeProtocols {
                                // A incrementally increasing, append-only list of protocol IDs.
                                // We don't use an enum so solidity doesn't throw when we pass in a
                                // new protocol ID that hasn't been rolled up yet.
                                uint128 internal constant UNKNOWN = 0;
                                uint128 internal constant CURVE = 1;
                                uint128 internal constant UNISWAPV2 = 2;
                                uint128 internal constant UNISWAP = 3;
                                uint128 internal constant BALANCER = 4;
                                uint128 internal constant KYBER = 5; // Not used: deprecated.
                                uint128 internal constant MOONISWAP = 6;
                                uint128 internal constant MSTABLE = 7;
                                uint128 internal constant OASIS = 8; // Not used: deprecated.
                                uint128 internal constant SHELL = 9;
                                uint128 internal constant DODO = 10;
                                uint128 internal constant DODOV2 = 11;
                                uint128 internal constant CRYPTOCOM = 12;
                                uint128 internal constant BANCOR = 13;
                                uint128 internal constant COFIX = 14; // Not used: deprecated.
                                uint128 internal constant NERVE = 15;
                                uint128 internal constant MAKERPSM = 16;
                                uint128 internal constant BALANCERV2 = 17;
                                uint128 internal constant UNISWAPV3 = 18;
                                uint128 internal constant KYBERDMM = 19;
                                uint128 internal constant CURVEV2 = 20;
                                uint128 internal constant LIDO = 21;
                                uint128 internal constant CLIPPER = 22; // Not used: Clipper is now using PLP interface
                                uint128 internal constant AAVEV2 = 23;
                                uint128 internal constant COMPOUND = 24;
                                uint128 internal constant BALANCERV2BATCH = 25;
                                uint128 internal constant GMX = 26;
                                uint128 internal constant PLATYPUS = 27;
                                uint128 internal constant BANCORV3 = 28;
                                uint128 internal constant SOLIDLY = 29;
                                uint128 internal constant SYNTHETIX = 30;
                                uint128 internal constant WOOFI = 31;
                                uint128 internal constant AAVEV3 = 32;
                                uint128 internal constant KYBERELASTIC = 33;
                                uint128 internal constant BARTER = 34;
                                uint128 internal constant TRADERJOEV2 = 35;
                                uint128 internal constant VELODROMEV2 = 36;
                                uint128 internal constant MAVERICK = 37;
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            // Minimal Aave V2 LendingPool interface
                            interface ILendingPool {
                                /**
                                 * @dev Deposits an `amount` of underlying asset into the reserve, receiving in return overlying aTokens.
                                 * - E.g. User deposits 100 USDC and gets in return 100 aUSDC
                                 * @param asset The address of the underlying asset to deposit
                                 * @param amount The amount to be deposited
                                 * @param onBehalfOf The address that will receive the aTokens, same as msg.sender if the user
                                 *   wants to receive them on his own wallet, or a different address if the beneficiary of aTokens
                                 *   is a different wallet
                                 * @param referralCode Code used to register the integrator originating the operation, for potential rewards.
                                 *   0 if the action is executed directly by the user, without any middle-man
                                 **/
                                function deposit(address asset, uint256 amount, address onBehalfOf, uint16 referralCode) external;
                                /**
                                 * @dev Withdraws an `amount` of underlying asset from the reserve, burning the equivalent aTokens owned
                                 * E.g. User has 100 aUSDC, calls withdraw() and receives 100 USDC, burning the 100 aUSDC
                                 * @param asset The address of the underlying asset to withdraw
                                 * @param amount The underlying amount to be withdrawn
                                 *   - Send the value type(uint256).max in order to withdraw the whole aToken balance
                                 * @param to Address that will receive the underlying, same as msg.sender if the user
                                 *   wants to receive it on his own wallet, or a different address if the beneficiary is a
                                 *   different wallet
                                 * @return The final amount withdrawn
                                 **/
                                function withdraw(address asset, uint256 amount, address to) external returns (uint256);
                            }
                            contract MixinAaveV2 {
                                using LibERC20TokenV06 for IERC20Token;
                                function _tradeAaveV2(
                                    IERC20Token sellToken,
                                    IERC20Token buyToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256) {
                                    (ILendingPool lendingPool, address aToken) = abi.decode(bridgeData, (ILendingPool, address));
                                    sellToken.approveIfBelow(address(lendingPool), sellAmount);
                                    if (address(buyToken) == aToken) {
                                        lendingPool.deposit(address(sellToken), sellAmount, address(this), 0);
                                        // 1:1 mapping token -> aToken and have the same number of decimals as the underlying token
                                        return sellAmount;
                                    } else if (address(sellToken) == aToken) {
                                        return lendingPool.withdraw(address(buyToken), sellAmount, address(this));
                                    }
                                    revert("MixinAaveV2/UNSUPPORTED_TOKEN_PAIR");
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibBytesV06.sol";
                            import "../IERC20Token.sol";
                            library LibERC20TokenV06 {
                                bytes private constant DECIMALS_CALL_DATA = hex"313ce567";
                                /// @dev Calls `IERC20Token(token).approve()`.
                                ///      Reverts if the return data is invalid or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param spender The address that receives an allowance.
                                /// @param allowance The allowance to set.
                                function compatApprove(IERC20Token token, address spender, uint256 allowance) internal {
                                    bytes memory callData = abi.encodeWithSelector(token.approve.selector, spender, allowance);
                                    _callWithOptionalBooleanResult(address(token), callData);
                                }
                                /// @dev Calls `IERC20Token(token).approve()` and sets the allowance to the
                                ///      maximum if the current approval is not already >= an amount.
                                ///      Reverts if the return data is invalid or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param spender The address that receives an allowance.
                                /// @param amount The minimum allowance needed.
                                function approveIfBelow(IERC20Token token, address spender, uint256 amount) internal {
                                    if (token.allowance(address(this), spender) < amount) {
                                        compatApprove(token, spender, uint256(-1));
                                    }
                                }
                                /// @dev Calls `IERC20Token(token).transfer()`.
                                ///      Reverts if the return data is invalid or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param to The address that receives the tokens
                                /// @param amount Number of tokens to transfer.
                                function compatTransfer(IERC20Token token, address to, uint256 amount) internal {
                                    bytes memory callData = abi.encodeWithSelector(token.transfer.selector, to, amount);
                                    _callWithOptionalBooleanResult(address(token), callData);
                                }
                                /// @dev Calls `IERC20Token(token).transferFrom()`.
                                ///      Reverts if the return data is invalid or the call reverts.
                                /// @param token The address of the token contract.
                                /// @param from The owner of the tokens.
                                /// @param to The address that receives the tokens
                                /// @param amount Number of tokens to transfer.
                                function compatTransferFrom(IERC20Token token, address from, address to, uint256 amount) internal {
                                    bytes memory callData = abi.encodeWithSelector(token.transferFrom.selector, from, to, amount);
                                    _callWithOptionalBooleanResult(address(token), callData);
                                }
                                /// @dev Retrieves the number of decimals for a token.
                                ///      Returns `18` if the call reverts.
                                /// @param token The address of the token contract.
                                /// @return tokenDecimals The number of decimals places for the token.
                                function compatDecimals(IERC20Token token) internal view returns (uint8 tokenDecimals) {
                                    tokenDecimals = 18;
                                    (bool didSucceed, bytes memory resultData) = address(token).staticcall(DECIMALS_CALL_DATA);
                                    if (didSucceed && resultData.length >= 32) {
                                        tokenDecimals = uint8(LibBytesV06.readUint256(resultData, 0));
                                    }
                                }
                                /// @dev Retrieves the allowance for a token, owner, and spender.
                                ///      Returns `0` if the call reverts.
                                /// @param token The address of the token contract.
                                /// @param owner The owner of the tokens.
                                /// @param spender The address the spender.
                                /// @return allowance_ The allowance for a token, owner, and spender.
                                function compatAllowance(
                                    IERC20Token token,
                                    address owner,
                                    address spender
                                ) internal view returns (uint256 allowance_) {
                                    (bool didSucceed, bytes memory resultData) = address(token).staticcall(
                                        abi.encodeWithSelector(token.allowance.selector, owner, spender)
                                    );
                                    if (didSucceed && resultData.length >= 32) {
                                        allowance_ = LibBytesV06.readUint256(resultData, 0);
                                    }
                                }
                                /// @dev Retrieves the balance for a token owner.
                                ///      Returns `0` if the call reverts.
                                /// @param token The address of the token contract.
                                /// @param owner The owner of the tokens.
                                /// @return balance The token balance of an owner.
                                function compatBalanceOf(IERC20Token token, address owner) internal view returns (uint256 balance) {
                                    (bool didSucceed, bytes memory resultData) = address(token).staticcall(
                                        abi.encodeWithSelector(token.balanceOf.selector, owner)
                                    );
                                    if (didSucceed && resultData.length >= 32) {
                                        balance = LibBytesV06.readUint256(resultData, 0);
                                    }
                                }
                                /// @dev Executes a call on address `target` with calldata `callData`
                                ///      and asserts that either nothing was returned or a single boolean
                                ///      was returned equal to `true`.
                                /// @param target The call target.
                                /// @param callData The abi-encoded call data.
                                function _callWithOptionalBooleanResult(address target, bytes memory callData) private {
                                    (bool didSucceed, bytes memory resultData) = target.call(callData);
                                    // Revert if the call reverted.
                                    if (!didSucceed) {
                                        LibRichErrorsV06.rrevert(resultData);
                                    }
                                    // If we get back 0 returndata, this may be a non-standard ERC-20 that
                                    // does not return a boolean. Check that it at least contains code.
                                    if (resultData.length == 0) {
                                        uint256 size;
                                        assembly {
                                            size := extcodesize(target)
                                        }
                                        require(size > 0, "invalid token address, contains no code");
                                        return;
                                    }
                                    // If we get back at least 32 bytes, we know the target address
                                    // contains code, and we assume it is a token that returned a boolean
                                    // success value, which must be true.
                                    if (resultData.length >= 32) {
                                        uint256 result = LibBytesV06.readUint256(resultData, 0);
                                        if (result == 1) {
                                            return;
                                        } else {
                                            LibRichErrorsV06.rrevert(resultData);
                                        }
                                    }
                                    // If 0 < returndatasize < 32, the target is a contract, but not a
                                    // valid token.
                                    LibRichErrorsV06.rrevert(resultData);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibRichErrorsV06 {
                                // bytes4(keccak256("Error(string)"))
                                bytes4 internal constant STANDARD_ERROR_SELECTOR = 0x08c379a0;
                                /// @dev ABI encode a standard, string revert error payload.
                                ///      This is the same payload that would be included by a `revert(string)`
                                ///      solidity statement. It has the function signature `Error(string)`.
                                /// @param message The error string.
                                /// @return The ABI encoded error.
                                function StandardError(string memory message) internal pure returns (bytes memory) {
                                    return abi.encodeWithSelector(STANDARD_ERROR_SELECTOR, bytes(message));
                                }
                                /// @dev Reverts an encoded rich revert reason `errorData`.
                                /// @param errorData ABI encoded error data.
                                function rrevert(bytes memory errorData) internal pure {
                                    assembly {
                                        revert(add(errorData, 0x20), mload(errorData))
                                    }
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./errors/LibBytesRichErrorsV06.sol";
                            import "./errors/LibRichErrorsV06.sol";
                            library LibBytesV06 {
                                using LibBytesV06 for bytes;
                                /// @dev Gets the memory address for a byte array.
                                /// @param input Byte array to lookup.
                                /// @return memoryAddress Memory address of byte array. This
                                ///         points to the header of the byte array which contains
                                ///         the length.
                                function rawAddress(bytes memory input) internal pure returns (uint256 memoryAddress) {
                                    assembly {
                                        memoryAddress := input
                                    }
                                    return memoryAddress;
                                }
                                /// @dev Gets the memory address for the contents of a byte array.
                                /// @param input Byte array to lookup.
                                /// @return memoryAddress Memory address of the contents of the byte array.
                                function contentAddress(bytes memory input) internal pure returns (uint256 memoryAddress) {
                                    assembly {
                                        memoryAddress := add(input, 32)
                                    }
                                    return memoryAddress;
                                }
                                /// @dev Copies `length` bytes from memory location `source` to `dest`.
                                /// @param dest memory address to copy bytes to.
                                /// @param source memory address to copy bytes from.
                                /// @param length number of bytes to copy.
                                function memCopy(uint256 dest, uint256 source, uint256 length) internal pure {
                                    if (length < 32) {
                                        // Handle a partial word by reading destination and masking
                                        // off the bits we are interested in.
                                        // This correctly handles overlap, zero lengths and source == dest
                                        assembly {
                                            let mask := sub(exp(256, sub(32, length)), 1)
                                            let s := and(mload(source), not(mask))
                                            let d := and(mload(dest), mask)
                                            mstore(dest, or(s, d))
                                        }
                                    } else {
                                        // Skip the O(length) loop when source == dest.
                                        if (source == dest) {
                                            return;
                                        }
                                        // For large copies we copy whole words at a time. The final
                                        // word is aligned to the end of the range (instead of after the
                                        // previous) to handle partial words. So a copy will look like this:
                                        //
                                        //  ####
                                        //      ####
                                        //          ####
                                        //            ####
                                        //
                                        // We handle overlap in the source and destination range by
                                        // changing the copying direction. This prevents us from
                                        // overwriting parts of source that we still need to copy.
                                        //
                                        // This correctly handles source == dest
                                        //
                                        if (source > dest) {
                                            assembly {
                                                // We subtract 32 from `sEnd` and `dEnd` because it
                                                // is easier to compare with in the loop, and these
                                                // are also the addresses we need for copying the
                                                // last bytes.
                                                length := sub(length, 32)
                                                let sEnd := add(source, length)
                                                let dEnd := add(dest, length)
                                                // Remember the last 32 bytes of source
                                                // This needs to be done here and not after the loop
                                                // because we may have overwritten the last bytes in
                                                // source already due to overlap.
                                                let last := mload(sEnd)
                                                // Copy whole words front to back
                                                // Note: the first check is always true,
                                                // this could have been a do-while loop.
                                                for {
                                                } lt(source, sEnd) {
                                                } {
                                                    mstore(dest, mload(source))
                                                    source := add(source, 32)
                                                    dest := add(dest, 32)
                                                }
                                                // Write the last 32 bytes
                                                mstore(dEnd, last)
                                            }
                                        } else {
                                            assembly {
                                                // We subtract 32 from `sEnd` and `dEnd` because those
                                                // are the starting points when copying a word at the end.
                                                length := sub(length, 32)
                                                let sEnd := add(source, length)
                                                let dEnd := add(dest, length)
                                                // Remember the first 32 bytes of source
                                                // This needs to be done here and not after the loop
                                                // because we may have overwritten the first bytes in
                                                // source already due to overlap.
                                                let first := mload(source)
                                                // Copy whole words back to front
                                                // We use a signed comparisson here to allow dEnd to become
                                                // negative (happens when source and dest < 32). Valid
                                                // addresses in local memory will never be larger than
                                                // 2**255, so they can be safely re-interpreted as signed.
                                                // Note: the first check is always true,
                                                // this could have been a do-while loop.
                                                for {
                                                } slt(dest, dEnd) {
                                                } {
                                                    mstore(dEnd, mload(sEnd))
                                                    sEnd := sub(sEnd, 32)
                                                    dEnd := sub(dEnd, 32)
                                                }
                                                // Write the first 32 bytes
                                                mstore(dest, first)
                                            }
                                        }
                                    }
                                }
                                /// @dev Returns a slices from a byte array.
                                /// @param b The byte array to take a slice from.
                                /// @param from The starting index for the slice (inclusive).
                                /// @param to The final index for the slice (exclusive).
                                /// @return result The slice containing bytes at indices [from, to)
                                function slice(bytes memory b, uint256 from, uint256 to) internal pure returns (bytes memory result) {
                                    // Ensure that the from and to positions are valid positions for a slice within
                                    // the byte array that is being used.
                                    if (from > to) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.FromLessThanOrEqualsToRequired,
                                                from,
                                                to
                                            )
                                        );
                                    }
                                    if (to > b.length) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.ToLessThanOrEqualsLengthRequired,
                                                to,
                                                b.length
                                            )
                                        );
                                    }
                                    // Create a new bytes structure and copy contents
                                    result = new bytes(to - from);
                                    memCopy(result.contentAddress(), b.contentAddress() + from, result.length);
                                    return result;
                                }
                                /// @dev Returns a slice from a byte array without preserving the input.
                                ///      When `from == 0`, the original array will match the slice.
                                ///      In other cases its state will be corrupted.
                                /// @param b The byte array to take a slice from. Will be destroyed in the process.
                                /// @param from The starting index for the slice (inclusive).
                                /// @param to The final index for the slice (exclusive).
                                /// @return result The slice containing bytes at indices [from, to)
                                function sliceDestructive(bytes memory b, uint256 from, uint256 to) internal pure returns (bytes memory result) {
                                    // Ensure that the from and to positions are valid positions for a slice within
                                    // the byte array that is being used.
                                    if (from > to) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.FromLessThanOrEqualsToRequired,
                                                from,
                                                to
                                            )
                                        );
                                    }
                                    if (to > b.length) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.ToLessThanOrEqualsLengthRequired,
                                                to,
                                                b.length
                                            )
                                        );
                                    }
                                    // Create a new bytes structure around [from, to) in-place.
                                    assembly {
                                        result := add(b, from)
                                        mstore(result, sub(to, from))
                                    }
                                    return result;
                                }
                                /// @dev Pops the last byte off of a byte array by modifying its length.
                                /// @param b Byte array that will be modified.
                                /// @return result The byte that was popped off.
                                function popLastByte(bytes memory b) internal pure returns (bytes1 result) {
                                    if (b.length == 0) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanZeroRequired,
                                                b.length,
                                                0
                                            )
                                        );
                                    }
                                    // Store last byte.
                                    result = b[b.length - 1];
                                    assembly {
                                        // Decrement length of byte array.
                                        let newLen := sub(mload(b), 1)
                                        mstore(b, newLen)
                                    }
                                    return result;
                                }
                                /// @dev Tests equality of two byte arrays.
                                /// @param lhs First byte array to compare.
                                /// @param rhs Second byte array to compare.
                                /// @return equal True if arrays are the same. False otherwise.
                                function equals(bytes memory lhs, bytes memory rhs) internal pure returns (bool equal) {
                                    // Keccak gas cost is 30 + numWords * 6. This is a cheap way to compare.
                                    // We early exit on unequal lengths, but keccak would also correctly
                                    // handle this.
                                    return lhs.length == rhs.length && keccak256(lhs) == keccak256(rhs);
                                }
                                /// @dev Reads an address from a position in a byte array.
                                /// @param b Byte array containing an address.
                                /// @param index Index in byte array of address.
                                /// @return result address from byte array.
                                function readAddress(bytes memory b, uint256 index) internal pure returns (address result) {
                                    if (b.length < index + 20) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsTwentyRequired,
                                                b.length,
                                                index + 20 // 20 is length of address
                                            )
                                        );
                                    }
                                    // Add offset to index:
                                    // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
                                    // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
                                    index += 20;
                                    // Read address from array memory
                                    assembly {
                                        // 1. Add index to address of bytes array
                                        // 2. Load 32-byte word from memory
                                        // 3. Apply 20-byte mask to obtain address
                                        result := and(mload(add(b, index)), 0xffffffffffffffffffffffffffffffffffffffff)
                                    }
                                    return result;
                                }
                                /// @dev Writes an address into a specific position in a byte array.
                                /// @param b Byte array to insert address into.
                                /// @param index Index in byte array of address.
                                /// @param input Address to put into byte array.
                                function writeAddress(bytes memory b, uint256 index, address input) internal pure {
                                    if (b.length < index + 20) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsTwentyRequired,
                                                b.length,
                                                index + 20 // 20 is length of address
                                            )
                                        );
                                    }
                                    // Add offset to index:
                                    // 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
                                    // 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
                                    index += 20;
                                    // Store address into array memory
                                    assembly {
                                        // The address occupies 20 bytes and mstore stores 32 bytes.
                                        // First fetch the 32-byte word where we'll be storing the address, then
                                        // apply a mask so we have only the bytes in the word that the address will not occupy.
                                        // Then combine these bytes with the address and store the 32 bytes back to memory with mstore.
                                        // 1. Add index to address of bytes array
                                        // 2. Load 32-byte word from memory
                                        // 3. Apply 12-byte mask to obtain extra bytes occupying word of memory where we'll store the address
                                        let neighbors := and(
                                            mload(add(b, index)),
                                            0xffffffffffffffffffffffff0000000000000000000000000000000000000000
                                        )
                                        // Make sure input address is clean.
                                        // (Solidity does not guarantee this)
                                        input := and(input, 0xffffffffffffffffffffffffffffffffffffffff)
                                        // Store the neighbors and address into memory
                                        mstore(add(b, index), xor(input, neighbors))
                                    }
                                }
                                /// @dev Reads a bytes32 value from a position in a byte array.
                                /// @param b Byte array containing a bytes32 value.
                                /// @param index Index in byte array of bytes32 value.
                                /// @return result bytes32 value from byte array.
                                function readBytes32(bytes memory b, uint256 index) internal pure returns (bytes32 result) {
                                    if (b.length < index + 32) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsThirtyTwoRequired,
                                                b.length,
                                                index + 32
                                            )
                                        );
                                    }
                                    // Arrays are prefixed by a 256 bit length parameter
                                    index += 32;
                                    // Read the bytes32 from array memory
                                    assembly {
                                        result := mload(add(b, index))
                                    }
                                    return result;
                                }
                                /// @dev Writes a bytes32 into a specific position in a byte array.
                                /// @param b Byte array to insert <input> into.
                                /// @param index Index in byte array of <input>.
                                /// @param input bytes32 to put into byte array.
                                function writeBytes32(bytes memory b, uint256 index, bytes32 input) internal pure {
                                    if (b.length < index + 32) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsThirtyTwoRequired,
                                                b.length,
                                                index + 32
                                            )
                                        );
                                    }
                                    // Arrays are prefixed by a 256 bit length parameter
                                    index += 32;
                                    // Read the bytes32 from array memory
                                    assembly {
                                        mstore(add(b, index), input)
                                    }
                                }
                                /// @dev Reads a uint256 value from a position in a byte array.
                                /// @param b Byte array containing a uint256 value.
                                /// @param index Index in byte array of uint256 value.
                                /// @return result uint256 value from byte array.
                                function readUint256(bytes memory b, uint256 index) internal pure returns (uint256 result) {
                                    result = uint256(readBytes32(b, index));
                                    return result;
                                }
                                /// @dev Writes a uint256 into a specific position in a byte array.
                                /// @param b Byte array to insert <input> into.
                                /// @param index Index in byte array of <input>.
                                /// @param input uint256 to put into byte array.
                                function writeUint256(bytes memory b, uint256 index, uint256 input) internal pure {
                                    writeBytes32(b, index, bytes32(input));
                                }
                                /// @dev Reads an unpadded bytes4 value from a position in a byte array.
                                /// @param b Byte array containing a bytes4 value.
                                /// @param index Index in byte array of bytes4 value.
                                /// @return result bytes4 value from byte array.
                                function readBytes4(bytes memory b, uint256 index) internal pure returns (bytes4 result) {
                                    if (b.length < index + 4) {
                                        LibRichErrorsV06.rrevert(
                                            LibBytesRichErrorsV06.InvalidByteOperationError(
                                                LibBytesRichErrorsV06.InvalidByteOperationErrorCodes.LengthGreaterThanOrEqualsFourRequired,
                                                b.length,
                                                index + 4
                                            )
                                        );
                                    }
                                    // Arrays are prefixed by a 32 byte length field
                                    index += 32;
                                    // Read the bytes4 from array memory
                                    assembly {
                                        result := mload(add(b, index))
                                        // Solidity does not require us to clean the trailing bytes.
                                        // We do it anyway
                                        result := and(result, 0xFFFFFFFF00000000000000000000000000000000000000000000000000000000)
                                    }
                                    return result;
                                }
                                /// @dev Writes a new length to a byte array.
                                ///      Decreasing length will lead to removing the corresponding lower order bytes from the byte array.
                                ///      Increasing length may lead to appending adjacent in-memory bytes to the end of the byte array.
                                /// @param b Bytes array to write new length to.
                                /// @param length New length of byte array.
                                function writeLength(bytes memory b, uint256 length) internal pure {
                                    assembly {
                                        mstore(b, length)
                                    }
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibBytesRichErrorsV06 {
                                enum InvalidByteOperationErrorCodes {
                                    FromLessThanOrEqualsToRequired,
                                    ToLessThanOrEqualsLengthRequired,
                                    LengthGreaterThanZeroRequired,
                                    LengthGreaterThanOrEqualsFourRequired,
                                    LengthGreaterThanOrEqualsTwentyRequired,
                                    LengthGreaterThanOrEqualsThirtyTwoRequired,
                                    LengthGreaterThanOrEqualsNestedBytesLengthRequired,
                                    DestinationLengthGreaterThanOrEqualSourceLengthRequired
                                }
                                // bytes4(keccak256("InvalidByteOperationError(uint8,uint256,uint256)"))
                                bytes4 internal constant INVALID_BYTE_OPERATION_ERROR_SELECTOR = 0x28006595;
                                function InvalidByteOperationError(
                                    InvalidByteOperationErrorCodes errorCode,
                                    uint256 offset,
                                    uint256 required
                                ) internal pure returns (bytes memory) {
                                    return abi.encodeWithSelector(INVALID_BYTE_OPERATION_ERROR_SELECTOR, errorCode, offset, required);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            interface IBalancerPool {
                                /// @dev Sell `tokenAmountIn` of `tokenIn` and receive `tokenOut`.
                                /// @param tokenIn The token being sold
                                /// @param tokenAmountIn The amount of `tokenIn` to sell.
                                /// @param tokenOut The token being bought.
                                /// @param minAmountOut The minimum amount of `tokenOut` to buy.
                                /// @param maxPrice The maximum value for `spotPriceAfter`.
                                /// @return tokenAmountOut The amount of `tokenOut` bought.
                                /// @return spotPriceAfter The new marginal spot price of the given
                                ///         token pair for this pool.
                                function swapExactAmountIn(
                                    IERC20Token tokenIn,
                                    uint256 tokenAmountIn,
                                    IERC20Token tokenOut,
                                    uint256 minAmountOut,
                                    uint256 maxPrice
                                ) external returns (uint256 tokenAmountOut, uint256 spotPriceAfter);
                            }
                            contract MixinBalancer {
                                using LibERC20TokenV06 for IERC20Token;
                                function _tradeBalancer(
                                    IERC20Token sellToken,
                                    IERC20Token buyToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256 boughtAmount) {
                                    // Decode the bridge data.
                                    IBalancerPool pool = abi.decode(bridgeData, (IBalancerPool));
                                    sellToken.approveIfBelow(address(pool), sellAmount);
                                    // Sell all of this contract's `sellToken` token balance.
                                    (boughtAmount, ) = pool.swapExactAmountIn(
                                        sellToken, // tokenIn
                                        sellAmount, // tokenAmountIn
                                        buyToken, // tokenOut
                                        1, // minAmountOut
                                        uint256(-1) // maxPrice
                                    );
                                    return boughtAmount;
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            interface IBalancerV2BatchSwapVault {
                                enum SwapKind {
                                    GIVEN_IN,
                                    GIVEN_OUT
                                }
                                struct BatchSwapStep {
                                    bytes32 poolId;
                                    uint256 assetInIndex;
                                    uint256 assetOutIndex;
                                    uint256 amount;
                                    bytes userData;
                                }
                                struct FundManagement {
                                    address sender;
                                    bool fromInternalBalance;
                                    address payable recipient;
                                    bool toInternalBalance;
                                }
                                function batchSwap(
                                    SwapKind kind,
                                    BatchSwapStep[] calldata swaps,
                                    IERC20Token[] calldata assets,
                                    FundManagement calldata funds,
                                    int256[] calldata limits,
                                    uint256 deadline
                                ) external returns (int256[] memory amounts);
                            }
                            contract MixinBalancerV2Batch {
                                using LibERC20TokenV06 for IERC20Token;
                                struct BalancerV2BatchBridgeData {
                                    IBalancerV2BatchSwapVault vault;
                                    IBalancerV2BatchSwapVault.BatchSwapStep[] swapSteps;
                                    IERC20Token[] assets;
                                }
                                function _tradeBalancerV2Batch(
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256 boughtAmount) {
                                    // Decode the bridge data.
                                    (
                                        IBalancerV2BatchSwapVault vault,
                                        IBalancerV2BatchSwapVault.BatchSwapStep[] memory swapSteps,
                                        address[] memory assets_
                                    ) = abi.decode(bridgeData, (IBalancerV2BatchSwapVault, IBalancerV2BatchSwapVault.BatchSwapStep[], address[]));
                                    IERC20Token[] memory assets;
                                    assembly {
                                        assets := assets_
                                    }
                                    // Grant an allowance to the exchange to spend `fromTokenAddress` token.
                                    assets[0].approveIfBelow(address(vault), sellAmount);
                                    swapSteps[0].amount = sellAmount;
                                    int256[] memory limits = new int256[](assets.length);
                                    for (uint256 i = 0; i < limits.length; ++i) {
                                        limits[i] = type(int256).max;
                                    }
                                    int256[] memory amounts = vault.batchSwap(
                                        IBalancerV2BatchSwapVault.SwapKind.GIVEN_IN,
                                        swapSteps,
                                        assets,
                                        IBalancerV2BatchSwapVault.FundManagement({
                                            sender: address(this),
                                            fromInternalBalance: false,
                                            recipient: payable(address(this)),
                                            toInternalBalance: false
                                        }),
                                        limits,
                                        block.timestamp + 1
                                    );
                                    require(amounts[amounts.length - 1] <= 0, "Unexpected BalancerV2Batch output");
                                    return uint256(amounts[amounts.length - 1] * -1);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "@0x/contracts-erc20/src/IEtherToken.sol";
                            /*
                                BancorV3
                            */
                            interface IBancorV3 {
                                /**
                                 * @dev performs a trade by providing the source amount and returns the target amount and the associated fee
                                 *
                                 * requirements:
                                 *
                                 * - the caller must be the network contract
                                 */
                                function tradeBySourceAmount(
                                    address sourceToken,
                                    address targetToken,
                                    uint256 sourceAmount,
                                    uint256 minReturnAmount,
                                    uint256 deadline,
                                    address beneficiary
                                ) external payable returns (uint256 amount);
                            }
                            contract MixinBancorV3 {
                                using LibERC20TokenV06 for IERC20Token;
                                IERC20Token public constant BANCORV3_ETH_ADDRESS = IERC20Token(0xEeeeeEeeeEeEeeEeEeEeeEEEeeeeEeeeeeeeEEeE);
                                IEtherToken private immutable WETH;
                                constructor(IEtherToken weth) public {
                                    WETH = weth;
                                }
                                function _tradeBancorV3(
                                    IERC20Token buyToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256 amountOut) {
                                    IBancorV3 router;
                                    IERC20Token[] memory path;
                                    address[] memory _path;
                                    uint256 payableAmount = 0;
                                    {
                                        (router, _path) = abi.decode(bridgeData, (IBancorV3, address[]));
                                        // To get around `abi.decode()` not supporting interface array types.
                                        assembly {
                                            path := _path
                                        }
                                    }
                                    require(path.length >= 2, "MixinBancorV3/PATH_LENGTH_MUST_BE_AT_LEAST_TWO");
                                    require(path[path.length - 1] == buyToken, "MixinBancorV3/LAST_ELEMENT_OF_PATH_MUST_MATCH_OUTPUT_TOKEN");
                                    //swap WETH->ETH as Bancor only deals in ETH
                                    if (_path[0] == address(WETH)) {
                                        //withdraw the sell amount of WETH for ETH
                                        WETH.withdraw(sellAmount);
                                        payableAmount = sellAmount;
                                        // set _path[0] to the ETH address if WETH is our buy token
                                        _path[0] = address(BANCORV3_ETH_ADDRESS);
                                    } else {
                                        // Grant the BancorV3 router an allowance to sell the first token.
                                        path[0].approveIfBelow(address(router), sellAmount);
                                    }
                                    // if we are buying WETH we need to swap to ETH and deposit into WETH after the swap
                                    if (_path[1] == address(WETH)) {
                                        _path[1] = address(BANCORV3_ETH_ADDRESS);
                                    }
                                    uint256 amountOut = router.tradeBySourceAmount{value: payableAmount}(
                                        _path[0],
                                        _path[1],
                                        // Sell all tokens we hold.
                                        sellAmount,
                                        // Minimum buy amount.
                                        1,
                                        //deadline
                                        block.timestamp + 1,
                                        // address of the mixin
                                        address(this)
                                    );
                                    // if we want to return WETH deposit the ETH amount we sold
                                    if (buyToken == WETH) {
                                        WETH.deposit{value: amountOut}();
                                    }
                                    return amountOut;
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./IERC20Token.sol";
                            interface IEtherToken is IERC20Token {
                                /// @dev Wrap ether.
                                function deposit() external payable;
                                /// @dev Unwrap ether.
                                function withdraw(uint256 amount) external;
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            contract MixinBarter {
                                using LibERC20TokenV06 for IERC20Token;
                                using LibRichErrorsV06 for bytes;
                                function _tradeBarter(
                                    IERC20Token sellToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256 boughtAmount) {
                                    (address barterRouter, bytes memory data) = abi.decode(bridgeData, (address, bytes));
                                    sellToken.approveIfBelow(barterRouter, sellAmount);
                                    (bool success, bytes memory resultData) = barterRouter.call(data);
                                    if (!success) {
                                        resultData.rrevert();
                                    }
                                    return abi.decode(resultData, (uint256));
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "@0x/contracts-erc20/src/IEtherToken.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            /// @dev Minimal CToken interface
                            interface ICToken {
                                /// @dev deposits specified amount underlying tokens and mints cToken for the sender
                                /// @param mintAmountInUnderlying amount of underlying tokens to deposit to mint cTokens
                                /// @return status code of whether the mint was successful or not
                                function mint(uint256 mintAmountInUnderlying) external returns (uint256);
                                /// @dev redeems specified amount of cTokens and returns the underlying token to the sender
                                /// @param redeemTokensInCtokens amount of cTokens to redeem for underlying collateral
                                /// @return status code of whether the redemption was successful or not
                                function redeem(uint256 redeemTokensInCtokens) external returns (uint256);
                            }
                            /// @dev Minimal CEther interface
                            interface ICEther {
                                /// @dev deposits the amount of Ether sent as value and return mints cEther for the sender
                                function mint() external payable;
                                /// @dev redeems specified amount of cETH and returns the underlying ether to the sender
                                /// @dev redeemTokensInCEther amount of cETH to redeem for underlying ether
                                /// @return status code of whether the redemption was successful or not
                                function redeem(uint256 redeemTokensInCEther) external returns (uint256);
                            }
                            contract MixinCompound {
                                using LibERC20TokenV06 for IERC20Token;
                                using LibSafeMathV06 for uint256;
                                IEtherToken private immutable WETH;
                                constructor(IEtherToken weth) public {
                                    WETH = weth;
                                }
                                uint256 private constant COMPOUND_SUCCESS_CODE = 0;
                                function _tradeCompound(
                                    IERC20Token sellToken,
                                    IERC20Token buyToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256) {
                                    address cTokenAddress = abi.decode(bridgeData, (address));
                                    uint256 beforeBalance = buyToken.balanceOf(address(this));
                                    if (address(buyToken) == cTokenAddress) {
                                        if (address(sellToken) == address(WETH)) {
                                            // ETH/WETH -> cETH
                                            ICEther cETH = ICEther(cTokenAddress);
                                            // Compound expects ETH to be sent with mint call
                                            WETH.withdraw(sellAmount);
                                            // NOTE: cETH mint will revert on failure instead of returning a status code
                                            cETH.mint{value: sellAmount}();
                                        } else {
                                            sellToken.approveIfBelow(cTokenAddress, sellAmount);
                                            // Token -> cToken
                                            ICToken cToken = ICToken(cTokenAddress);
                                            require(cToken.mint(sellAmount) == COMPOUND_SUCCESS_CODE, "MixinCompound/FAILED_TO_MINT_CTOKEN");
                                        }
                                    } else if (address(sellToken) == cTokenAddress) {
                                        if (address(buyToken) == address(WETH)) {
                                            // cETH -> ETH/WETH
                                            uint256 etherBalanceBefore = address(this).balance;
                                            ICEther cETH = ICEther(cTokenAddress);
                                            require(cETH.redeem(sellAmount) == COMPOUND_SUCCESS_CODE, "MixinCompound/FAILED_TO_REDEEM_CETHER");
                                            uint256 etherBalanceAfter = address(this).balance;
                                            uint256 receivedEtherBalance = etherBalanceAfter.safeSub(etherBalanceBefore);
                                            WETH.deposit{value: receivedEtherBalance}();
                                        } else {
                                            ICToken cToken = ICToken(cTokenAddress);
                                            require(cToken.redeem(sellAmount) == COMPOUND_SUCCESS_CODE, "MixinCompound/FAILED_TO_REDEEM_CTOKEN");
                                        }
                                    }
                                    return buyToken.balanceOf(address(this)).safeSub(beforeBalance);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "./errors/LibRichErrorsV06.sol";
                            import "./errors/LibSafeMathRichErrorsV06.sol";
                            library LibSafeMathV06 {
                                function safeMul(uint256 a, uint256 b) internal pure returns (uint256) {
                                    if (a == 0) {
                                        return 0;
                                    }
                                    uint256 c = a * b;
                                    if (c / a != b) {
                                        LibRichErrorsV06.rrevert(
                                            LibSafeMathRichErrorsV06.Uint256BinOpError(
                                                LibSafeMathRichErrorsV06.BinOpErrorCodes.MULTIPLICATION_OVERFLOW,
                                                a,
                                                b
                                            )
                                        );
                                    }
                                    return c;
                                }
                                function safeDiv(uint256 a, uint256 b) internal pure returns (uint256) {
                                    if (b == 0) {
                                        LibRichErrorsV06.rrevert(
                                            LibSafeMathRichErrorsV06.Uint256BinOpError(
                                                LibSafeMathRichErrorsV06.BinOpErrorCodes.DIVISION_BY_ZERO,
                                                a,
                                                b
                                            )
                                        );
                                    }
                                    uint256 c = a / b;
                                    return c;
                                }
                                function safeSub(uint256 a, uint256 b) internal pure returns (uint256) {
                                    if (b > a) {
                                        LibRichErrorsV06.rrevert(
                                            LibSafeMathRichErrorsV06.Uint256BinOpError(
                                                LibSafeMathRichErrorsV06.BinOpErrorCodes.SUBTRACTION_UNDERFLOW,
                                                a,
                                                b
                                            )
                                        );
                                    }
                                    return a - b;
                                }
                                function safeAdd(uint256 a, uint256 b) internal pure returns (uint256) {
                                    uint256 c = a + b;
                                    if (c < a) {
                                        LibRichErrorsV06.rrevert(
                                            LibSafeMathRichErrorsV06.Uint256BinOpError(
                                                LibSafeMathRichErrorsV06.BinOpErrorCodes.ADDITION_OVERFLOW,
                                                a,
                                                b
                                            )
                                        );
                                    }
                                    return c;
                                }
                                function max256(uint256 a, uint256 b) internal pure returns (uint256) {
                                    return a >= b ? a : b;
                                }
                                function min256(uint256 a, uint256 b) internal pure returns (uint256) {
                                    return a < b ? a : b;
                                }
                                function safeMul128(uint128 a, uint128 b) internal pure returns (uint128) {
                                    if (a == 0) {
                                        return 0;
                                    }
                                    uint128 c = a * b;
                                    if (c / a != b) {
                                        LibRichErrorsV06.rrevert(
                                            LibSafeMathRichErrorsV06.Uint256BinOpError(
                                                LibSafeMathRichErrorsV06.BinOpErrorCodes.MULTIPLICATION_OVERFLOW,
                                                a,
                                                b
                                            )
                                        );
                                    }
                                    return c;
                                }
                                function safeDiv128(uint128 a, uint128 b) internal pure returns (uint128) {
                                    if (b == 0) {
                                        LibRichErrorsV06.rrevert(
                                            LibSafeMathRichErrorsV06.Uint256BinOpError(
                                                LibSafeMathRichErrorsV06.BinOpErrorCodes.DIVISION_BY_ZERO,
                                                a,
                                                b
                                            )
                                        );
                                    }
                                    uint128 c = a / b;
                                    return c;
                                }
                                function safeSub128(uint128 a, uint128 b) internal pure returns (uint128) {
                                    if (b > a) {
                                        LibRichErrorsV06.rrevert(
                                            LibSafeMathRichErrorsV06.Uint256BinOpError(
                                                LibSafeMathRichErrorsV06.BinOpErrorCodes.SUBTRACTION_UNDERFLOW,
                                                a,
                                                b
                                            )
                                        );
                                    }
                                    return a - b;
                                }
                                function safeAdd128(uint128 a, uint128 b) internal pure returns (uint128) {
                                    uint128 c = a + b;
                                    if (c < a) {
                                        LibRichErrorsV06.rrevert(
                                            LibSafeMathRichErrorsV06.Uint256BinOpError(
                                                LibSafeMathRichErrorsV06.BinOpErrorCodes.ADDITION_OVERFLOW,
                                                a,
                                                b
                                            )
                                        );
                                    }
                                    return c;
                                }
                                function max128(uint128 a, uint128 b) internal pure returns (uint128) {
                                    return a >= b ? a : b;
                                }
                                function min128(uint128 a, uint128 b) internal pure returns (uint128) {
                                    return a < b ? a : b;
                                }
                                function safeDowncastToUint128(uint256 a) internal pure returns (uint128) {
                                    if (a > type(uint128).max) {
                                        LibRichErrorsV06.rrevert(
                                            LibSafeMathRichErrorsV06.Uint256DowncastError(
                                                LibSafeMathRichErrorsV06.DowncastErrorCodes.VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT128,
                                                a
                                            )
                                        );
                                    }
                                    return uint128(a);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2020 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            library LibSafeMathRichErrorsV06 {
                                // bytes4(keccak256("Uint256BinOpError(uint8,uint256,uint256)"))
                                bytes4 internal constant UINT256_BINOP_ERROR_SELECTOR = 0xe946c1bb;
                                // bytes4(keccak256("Uint256DowncastError(uint8,uint256)"))
                                bytes4 internal constant UINT256_DOWNCAST_ERROR_SELECTOR = 0xc996af7b;
                                enum BinOpErrorCodes {
                                    ADDITION_OVERFLOW,
                                    MULTIPLICATION_OVERFLOW,
                                    SUBTRACTION_UNDERFLOW,
                                    DIVISION_BY_ZERO
                                }
                                enum DowncastErrorCodes {
                                    VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT32,
                                    VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT64,
                                    VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT96,
                                    VALUE_TOO_LARGE_TO_DOWNCAST_TO_UINT128
                                }
                                function Uint256BinOpError(BinOpErrorCodes errorCode, uint256 a, uint256 b) internal pure returns (bytes memory) {
                                    return abi.encodeWithSelector(UINT256_BINOP_ERROR_SELECTOR, errorCode, a, b);
                                }
                                function Uint256DowncastError(DowncastErrorCodes errorCode, uint256 a) internal pure returns (bytes memory) {
                                    return abi.encodeWithSelector(UINT256_DOWNCAST_ERROR_SELECTOR, errorCode, a);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-erc20/src/IEtherToken.sol";
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            contract MixinCurve {
                                using LibERC20TokenV06 for IERC20Token;
                                using LibSafeMathV06 for uint256;
                                using LibRichErrorsV06 for bytes;
                                /// @dev Mainnet address of the WETH contract.
                                IEtherToken private immutable WETH;
                                constructor(IEtherToken weth) public {
                                    WETH = weth;
                                }
                                struct CurveBridgeData {
                                    address curveAddress;
                                    bytes4 exchangeFunctionSelector;
                                    int128 fromCoinIdx;
                                    int128 toCoinIdx;
                                }
                                function _tradeCurve(
                                    IERC20Token sellToken,
                                    IERC20Token buyToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256 boughtAmount) {
                                    // Decode the bridge data to get the Curve metadata.
                                    CurveBridgeData memory data = abi.decode(bridgeData, (CurveBridgeData));
                                    uint256 payableAmount;
                                    if (sellToken == WETH) {
                                        payableAmount = sellAmount;
                                        WETH.withdraw(sellAmount);
                                    } else {
                                        sellToken.approveIfBelow(data.curveAddress, sellAmount);
                                    }
                                    uint256 beforeBalance = buyToken.balanceOf(address(this));
                                    (bool success, bytes memory resultData) = data.curveAddress.call{value: payableAmount}(
                                        abi.encodeWithSelector(
                                            data.exchangeFunctionSelector,
                                            data.fromCoinIdx,
                                            data.toCoinIdx,
                                            // dx
                                            sellAmount,
                                            // min dy
                                            1
                                        )
                                    );
                                    if (!success) {
                                        resultData.rrevert();
                                    }
                                    if (buyToken == WETH) {
                                        boughtAmount = address(this).balance;
                                        WETH.deposit{value: boughtAmount}();
                                    }
                                    return buyToken.balanceOf(address(this)).safeSub(beforeBalance);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            contract MixinCurveV2 {
                                using LibERC20TokenV06 for IERC20Token;
                                using LibSafeMathV06 for uint256;
                                using LibRichErrorsV06 for bytes;
                                struct CurveBridgeDataV2 {
                                    address curveAddress;
                                    bytes4 exchangeFunctionSelector;
                                    int128 fromCoinIdx;
                                    int128 toCoinIdx;
                                }
                                function _tradeCurveV2(
                                    IERC20Token sellToken,
                                    IERC20Token buyToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256 boughtAmount) {
                                    // Decode the bridge data to get the Curve metadata.
                                    CurveBridgeDataV2 memory data = abi.decode(bridgeData, (CurveBridgeDataV2));
                                    sellToken.approveIfBelow(data.curveAddress, sellAmount);
                                    uint256 beforeBalance = buyToken.balanceOf(address(this));
                                    (bool success, bytes memory resultData) = data.curveAddress.call(
                                        abi.encodeWithSelector(
                                            data.exchangeFunctionSelector,
                                            data.fromCoinIdx,
                                            data.toCoinIdx,
                                            // dx
                                            sellAmount,
                                            // min dy
                                            1
                                        )
                                    );
                                    if (!success) {
                                        resultData.rrevert();
                                    }
                                    return buyToken.balanceOf(address(this)).safeSub(beforeBalance);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "./MixinUniswapV2.sol";
                            contract MixinCryptoCom {
                                using LibERC20TokenV06 for IERC20Token;
                                function _tradeCryptoCom(
                                    IERC20Token buyToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256 boughtAmount) {
                                    IUniswapV2Router02 router;
                                    IERC20Token[] memory path;
                                    {
                                        address[] memory _path;
                                        (router, _path) = abi.decode(bridgeData, (IUniswapV2Router02, address[]));
                                        // To get around `abi.decode()` not supporting interface array types.
                                        assembly {
                                            path := _path
                                        }
                                    }
                                    require(path.length >= 2, "MixinCryptoCom/PATH_LENGTH_MUST_BE_AT_LEAST_TWO");
                                    require(path[path.length - 1] == buyToken, "MixinCryptoCom/LAST_ELEMENT_OF_PATH_MUST_MATCH_OUTPUT_TOKEN");
                                    // Grant the CryptoCom router an allowance to sell the first token.
                                    path[0].approveIfBelow(address(router), sellAmount);
                                    uint256[] memory amounts = router.swapExactTokensForTokens(
                                        // Sell all tokens we hold.
                                        sellAmount,
                                        // Minimum buy amount.
                                        1,
                                        // Convert to `buyToken` along this path.
                                        path,
                                        // Recipient is `this`.
                                        address(this),
                                        // Expires after this block.
                                        block.timestamp
                                    );
                                    return amounts[amounts.length - 1];
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "../IBridgeAdapter.sol";
                            /*
                                UniswapV2
                            */
                            interface IUniswapV2Router02 {
                                /// @dev Swaps an exact amount of input tokens for as many output tokens as possible, along the route determined by
                                /// the path. The first element of path is the input token, the last is the output token, and any intermediate
                                /// elements represent intermediate pairs to trade through (if, for example, a direct pair does not exist).
                                /// @param amountIn The amount of input tokens to send.
                                /// @param amountOutMin The minimum amount of output tokens that must be received for the transaction not to revert.
                                /// @param path An array of token addresses. path.length must be >= 2. Pools for each consecutive pair of addresses
                                /// must exist and have liquidity.
                                /// @param to Recipient of the output tokens.
                                /// @param deadline Unix timestamp after which the transaction will revert.
                                /// @return amounts The input token amount and all subsequent output token amounts.
                                function swapExactTokensForTokens(
                                    uint256 amountIn,
                                    uint256 amountOutMin,
                                    IERC20Token[] calldata path,
                                    address to,
                                    uint256 deadline
                                ) external returns (uint256[] memory amounts);
                            }
                            contract MixinUniswapV2 {
                                using LibERC20TokenV06 for IERC20Token;
                                function _tradeUniswapV2(
                                    IERC20Token buyToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256 boughtAmount) {
                                    IUniswapV2Router02 router;
                                    IERC20Token[] memory path;
                                    {
                                        address[] memory _path;
                                        (router, _path) = abi.decode(bridgeData, (IUniswapV2Router02, address[]));
                                        // To get around `abi.decode()` not supporting interface array types.
                                        assembly {
                                            path := _path
                                        }
                                    }
                                    require(path.length >= 2, "MixinUniswapV2/PATH_LENGTH_MUST_BE_AT_LEAST_TWO");
                                    require(path[path.length - 1] == buyToken, "MixinUniswapV2/LAST_ELEMENT_OF_PATH_MUST_MATCH_OUTPUT_TOKEN");
                                    // Grant the Uniswap router an allowance to sell the first token.
                                    path[0].approveIfBelow(address(router), sellAmount);
                                    uint256[] memory amounts = router.swapExactTokensForTokens(
                                        // Sell all tokens we hold.
                                        sellAmount,
                                        // Minimum buy amount.
                                        1,
                                        // Convert to `buyToken` along this path.
                                        path,
                                        // Recipient is `this`.
                                        address(this),
                                        // Expires after this block.
                                        block.timestamp
                                    );
                                    return amounts[amounts.length - 1];
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "../IBridgeAdapter.sol";
                            interface IDODO {
                                function sellBaseToken(uint256 amount, uint256 minReceiveQuote, bytes calldata data) external returns (uint256);
                                function buyBaseToken(uint256 amount, uint256 maxPayQuote, bytes calldata data) external returns (uint256);
                            }
                            interface IDODOHelper {
                                function querySellQuoteToken(IDODO dodo, uint256 amount) external view returns (uint256);
                            }
                            contract MixinDodo {
                                using LibERC20TokenV06 for IERC20Token;
                                function _tradeDodo(
                                    IERC20Token sellToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256 boughtAmount) {
                                    (IDODOHelper helper, IDODO pool, bool isSellBase) = abi.decode(bridgeData, (IDODOHelper, IDODO, bool));
                                    // Grant the Dodo pool contract an allowance to sell the first token.
                                    sellToken.approveIfBelow(address(pool), sellAmount);
                                    if (isSellBase) {
                                        // Sell the Base token directly against the contract
                                        boughtAmount = pool.sellBaseToken(
                                            // amount to sell
                                            sellAmount,
                                            // min receive amount
                                            1,
                                            new bytes(0)
                                        );
                                    } else {
                                        // Need to re-calculate the sell quote amount into buyBase
                                        boughtAmount = helper.querySellQuoteToken(pool, sellAmount);
                                        pool.buyBaseToken(
                                            // amount to buy
                                            boughtAmount,
                                            // max pay amount
                                            sellAmount,
                                            new bytes(0)
                                        );
                                    }
                                    return boughtAmount;
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "../IBridgeAdapter.sol";
                            interface IDODOV2 {
                                function sellBase(address recipient) external returns (uint256);
                                function sellQuote(address recipient) external returns (uint256);
                            }
                            contract MixinDodoV2 {
                                using LibERC20TokenV06 for IERC20Token;
                                function _tradeDodoV2(
                                    IERC20Token sellToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256 boughtAmount) {
                                    (IDODOV2 pool, bool isSellBase) = abi.decode(bridgeData, (IDODOV2, bool));
                                    // Transfer the tokens into the pool
                                    sellToken.compatTransfer(address(pool), sellAmount);
                                    boughtAmount = isSellBase ? pool.sellBase(address(this)) : pool.sellQuote(address(this));
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2021 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "../IBridgeAdapter.sol";
                            /*
                                KyberDmm Router
                            */
                            interface IKyberDmmRouter {
                                /// @dev Swaps an exact amount of input tokens for as many output tokens as possible, along the route determined by
                                /// the path. The first element of path is the input token, the last is the output token, and any intermediate
                                /// elements represent intermediate pairs to trade through (if, for example, a direct pair does not exist).
                                /// @param amountIn The amount of input tokens to send.
                                /// @param amountOutMin The minimum amount of output tokens that must be received for the transaction not to revert.
                                /// @param pools An array of pool addresses. pools.length must be >= 1.
                                /// @param path An array of token addresses. path.length must be >= 2. Pools for each consecutive pair of addresses
                                /// must exist and have liquidity.
                                /// @param to Recipient of the output tokens.
                                /// @param deadline Unix timestamp after which the transaction will revert.
                                /// @return amounts The input token amount and all subsequent output token amounts.
                                function swapExactTokensForTokens(
                                    uint256 amountIn,
                                    uint256 amountOutMin,
                                    address[] calldata pools,
                                    address[] calldata path,
                                    address to,
                                    uint256 deadline
                                ) external returns (uint256[] memory amounts);
                            }
                            contract MixinKyberDmm {
                                using LibERC20TokenV06 for IERC20Token;
                                function _tradeKyberDmm(
                                    IERC20Token buyToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256 boughtAmount) {
                                    address router;
                                    address[] memory pools;
                                    address[] memory path;
                                    (router, pools, path) = abi.decode(bridgeData, (address, address[], address[]));
                                    require(pools.length >= 1, "MixinKyberDmm/POOLS_LENGTH_MUST_BE_AT_LEAST_ONE");
                                    require(path.length == pools.length + 1, "MixinKyberDmm/ARRAY_LENGTH_MISMATCH");
                                    require(
                                        path[path.length - 1] == address(buyToken),
                                        "MixinKyberDmm/LAST_ELEMENT_OF_PATH_MUST_MATCH_OUTPUT_TOKEN"
                                    );
                                    // Grant the KyberDmm router an allowance to sell the first token.
                                    IERC20Token(path[0]).approveIfBelow(address(router), sellAmount);
                                    uint256[] memory amounts = IKyberDmmRouter(router).swapExactTokensForTokens(
                                        // Sell all tokens we hold.
                                        sellAmount,
                                        // Minimum buy amount.
                                        1,
                                        pools,
                                        // Convert to `buyToken` along this path.
                                        path,
                                        // Recipient is `this`.
                                        address(this),
                                        // Expires after this block.
                                        block.timestamp
                                    );
                                    return amounts[amounts.length - 1];
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            interface IKyberElasticRouter {
                                struct ExactInputParams {
                                    bytes path;
                                    address recipient;
                                    uint256 deadline;
                                    uint256 amountIn;
                                    uint256 minAmountOut;
                                }
                                function swapExactInput(ExactInputParams calldata params) external payable returns (uint256 amountOut);
                            }
                            contract MixinKyberElastic {
                                using LibERC20TokenV06 for IERC20Token;
                                function _tradeKyberElastic(
                                    IERC20Token sellToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256 boughtAmount) {
                                    (IKyberElasticRouter router, bytes memory path) = abi.decode(bridgeData, (IKyberElasticRouter, bytes));
                                    // Grant the Kyber router an allowance to sell the sell token.
                                    sellToken.approveIfBelow(address(router), sellAmount);
                                    boughtAmount = router.swapExactInput(
                                        IKyberElasticRouter.ExactInputParams({
                                            path: path,
                                            recipient: address(this),
                                            deadline: block.timestamp,
                                            amountIn: sellAmount,
                                            minAmountOut: 1
                                        })
                                    );
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "@0x/contracts-erc20/src/IEtherToken.sol";
                            /// @dev Minimal interface for minting StETH
                            interface IStETH {
                                /// @dev Adds eth to the pool
                                /// @param _referral optional address for referrals
                                /// @return StETH Amount of shares generated
                                function submit(address _referral) external payable returns (uint256 StETH);
                                /// @dev Retrieve the current pooled ETH representation of the shares amount
                                /// @param _sharesAmount amount of shares
                                /// @return amount of pooled ETH represented by the shares amount
                                function getPooledEthByShares(uint256 _sharesAmount) external view returns (uint256);
                            }
                            /// @dev Minimal interface for wrapping/unwrapping stETH.
                            interface IWstETH {
                                /**
                                 * @notice Exchanges stETH to wstETH
                                 * @param _stETHAmount amount of stETH to wrap in exchange for wstETH
                                 * @dev Requirements:
                                 *  - `_stETHAmount` must be non-zero
                                 *  - msg.sender must approve at least `_stETHAmount` stETH to this
                                 *    contract.
                                 *  - msg.sender must have at least `_stETHAmount` of stETH.
                                 * User should first approve _stETHAmount to the WstETH contract
                                 * @return Amount of wstETH user receives after wrap
                                 */
                                function wrap(uint256 _stETHAmount) external returns (uint256);
                                /**
                                 * @notice Exchanges wstETH to stETH
                                 * @param _wstETHAmount amount of wstETH to uwrap in exchange for stETH
                                 * @dev Requirements:
                                 *  - `_wstETHAmount` must be non-zero
                                 *  - msg.sender must have at least `_wstETHAmount` wstETH.
                                 * @return Amount of stETH user receives after unwrap
                                 */
                                function unwrap(uint256 _wstETHAmount) external returns (uint256);
                            }
                            contract MixinLido {
                                using LibERC20TokenV06 for IERC20Token;
                                using LibERC20TokenV06 for IEtherToken;
                                IEtherToken private immutable WETH;
                                constructor(IEtherToken weth) public {
                                    WETH = weth;
                                }
                                function _tradeLido(
                                    IERC20Token sellToken,
                                    IERC20Token buyToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256 boughtAmount) {
                                    if (address(sellToken) == address(WETH)) {
                                        return _tradeStETH(buyToken, sellAmount, bridgeData);
                                    }
                                    return _tradeWstETH(sellToken, buyToken, sellAmount, bridgeData);
                                }
                                function _tradeStETH(
                                    IERC20Token buyToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) private returns (uint256 boughtAmount) {
                                    IStETH stETH = abi.decode(bridgeData, (IStETH));
                                    if (address(buyToken) == address(stETH)) {
                                        WETH.withdraw(sellAmount);
                                        return stETH.getPooledEthByShares(stETH.submit{value: sellAmount}(address(0)));
                                    }
                                    revert("MixinLido/UNSUPPORTED_TOKEN_PAIR");
                                }
                                function _tradeWstETH(
                                    IERC20Token sellToken,
                                    IERC20Token buyToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) private returns (uint256 boughtAmount) {
                                    (IEtherToken stETH, IWstETH wstETH) = abi.decode(bridgeData, (IEtherToken, IWstETH));
                                    if (address(sellToken) == address(stETH) && address(buyToken) == address(wstETH)) {
                                        sellToken.approveIfBelow(address(wstETH), sellAmount);
                                        return wstETH.wrap(sellAmount);
                                    }
                                    if (address(sellToken) == address(wstETH) && address(buyToken) == address(stETH)) {
                                        return wstETH.unwrap(sellAmount);
                                    }
                                    revert("MixinLido/UNSUPPORTED_TOKEN_PAIR");
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            interface IPSM {
                                // @dev Get the fee for selling USDC to DAI in PSM
                                // @return tin toll in [wad]
                                function tin() external view returns (uint256);
                                // @dev Get the fee for selling DAI to USDC in PSM
                                // @return tout toll out [wad]
                                function tout() external view returns (uint256);
                                // @dev Get the address of the PSM state Vat
                                // @return address of the Vat
                                function vat() external view returns (address);
                                // @dev Get the address of the underlying vault powering PSM
                                // @return address of gemJoin contract
                                function gemJoin() external view returns (address);
                                // @dev Sell USDC for DAI
                                // @param usr The address of the account trading USDC for DAI.
                                // @param gemAmt The amount of USDC to sell in USDC base units
                                function sellGem(address usr, uint256 gemAmt) external;
                                // @dev Buy USDC for DAI
                                // @param usr The address of the account trading DAI for USDC
                                // @param gemAmt The amount of USDC to buy in USDC base units
                                function buyGem(address usr, uint256 gemAmt) external;
                            }
                            contract MixinMakerPSM {
                                using LibERC20TokenV06 for IERC20Token;
                                using LibSafeMathV06 for uint256;
                                struct MakerPsmBridgeData {
                                    address psmAddress;
                                    address gemTokenAddres;
                                }
                                // Maker units
                                // wad: fixed point decimal with 18 decimals (for basic quantities, e.g. balances)
                                uint256 private constant WAD = 10 ** 18;
                                // ray: fixed point decimal with 27 decimals (for precise quantites, e.g. ratios)
                                uint256 private constant RAY = 10 ** 27;
                                // rad: fixed point decimal with 45 decimals (result of integer multiplication with a wad and a ray)
                                uint256 private constant RAD = 10 ** 45;
                                // See https://github.com/makerdao/dss/blob/master/DEVELOPING.md
                                function _tradeMakerPsm(
                                    IERC20Token sellToken,
                                    IERC20Token buyToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256 boughtAmount) {
                                    // Decode the bridge data.
                                    MakerPsmBridgeData memory data = abi.decode(bridgeData, (MakerPsmBridgeData));
                                    uint256 beforeBalance = buyToken.balanceOf(address(this));
                                    IPSM psm = IPSM(data.psmAddress);
                                    if (address(sellToken) == data.gemTokenAddres) {
                                        sellToken.approveIfBelow(psm.gemJoin(), sellAmount);
                                        psm.sellGem(address(this), sellAmount);
                                    } else if (address(buyToken) == data.gemTokenAddres) {
                                        uint256 feeDivisor = WAD.safeAdd(psm.tout()); // eg. 1.001 * 10 ** 18 with 0.1% fee [tout is in wad];
                                        uint256 buyTokenBaseUnit = uint256(10) ** uint256(buyToken.decimals());
                                        uint256 gemAmount = sellAmount.safeMul(buyTokenBaseUnit).safeDiv(feeDivisor);
                                        sellToken.approveIfBelow(data.psmAddress, sellAmount);
                                        psm.buyGem(address(this), gemAmount);
                                    }
                                    return buyToken.balanceOf(address(this)).safeSub(beforeBalance);
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            interface IMaverickV1Router {
                                struct ExactInputSingleParams {
                                    address tokenIn;
                                    address tokenOut;
                                    address pool;
                                    address recipient;
                                    uint256 deadline;
                                    uint256 amountIn;
                                    uint256 amountOutMinimum;
                                    uint256 sqrtPriceLimitD18;
                                }
                                function exactInputSingle(ExactInputSingleParams calldata params) external payable returns (uint256 amountOut);
                            }
                            contract MixinMaverickV1 {
                                using LibERC20TokenV06 for IERC20Token;
                                function _tradeMaverickV1(
                                    IERC20Token sellToken,
                                    IERC20Token buyToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256 boughtAmount) {
                                    (IMaverickV1Router router, address pool) = abi.decode(bridgeData, (IMaverickV1Router, address));
                                    // Grant the MaverickV1 router an allowance to sell the sellToken
                                    sellToken.approveIfBelow(address(router), sellAmount);
                                    boughtAmount = router.exactInputSingle(
                                        IMaverickV1Router.ExactInputSingleParams({
                                            tokenIn: address(sellToken),
                                            tokenOut: address(buyToken),
                                            pool: pool,
                                            recipient: address(this),
                                            deadline: block.timestamp,
                                            amountIn: sellAmount,
                                            amountOutMinimum: 1,
                                            sqrtPriceLimitD18: 0
                                        })
                                    );
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-utils/contracts/src/v06/errors/LibRichErrorsV06.sol";
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            contract MixinNerve {
                                using LibERC20TokenV06 for IERC20Token;
                                using LibSafeMathV06 for uint256;
                                using LibRichErrorsV06 for bytes;
                                struct NerveBridgeData {
                                    address pool;
                                    bytes4 exchangeFunctionSelector;
                                    int128 fromCoinIdx;
                                    int128 toCoinIdx;
                                }
                                function _tradeNerve(
                                    IERC20Token sellToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256 boughtAmount) {
                                    // Basically a Curve fork but the swap option has a deadline
                                    // Decode the bridge data to get the Curve metadata.
                                    NerveBridgeData memory data = abi.decode(bridgeData, (NerveBridgeData));
                                    sellToken.approveIfBelow(data.pool, sellAmount);
                                    (bool success, bytes memory resultData) = data.pool.call(
                                        abi.encodeWithSelector(
                                            data.exchangeFunctionSelector,
                                            data.fromCoinIdx,
                                            data.toCoinIdx,
                                            // dx
                                            sellAmount,
                                            // min dy
                                            1,
                                            // deadline
                                            block.timestamp
                                        )
                                    );
                                    if (!success) {
                                        resultData.rrevert();
                                    }
                                    return abi.decode(resultData, (uint256));
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            interface ISynthetix {
                                // Ethereum Mainnet
                                function exchangeAtomically(
                                    bytes32 sourceCurrencyKey,
                                    uint256 sourceAmount,
                                    bytes32 destinationCurrencyKey,
                                    bytes32 trackingCode,
                                    uint256 minAmount
                                ) external returns (uint256 amountReceived);
                                // Optimism
                                function exchangeWithTracking(
                                    bytes32 sourceCurrencyKey,
                                    uint256 sourceAmount,
                                    bytes32 destinationCurrencyKey,
                                    address rewardAddress,
                                    bytes32 trackingCode
                                ) external returns (uint256 amountReceived);
                            }
                            contract MixinSynthetix {
                                // solhint-disable-next-line const-name-snakecase
                                address private constant rewardAddress = 0x5C80239D97E1eB216b5c3D8fBa5DE5Be5d38e4C9;
                                // solhint-disable-next-line const-name-snakecase
                                bytes32 constant trackingCode = 0x3058000000000000000000000000000000000000000000000000000000000000;
                                function _tradeSynthetix(uint256 sellAmount, bytes memory bridgeData) public returns (uint256 boughtAmount) {
                                    (ISynthetix synthetix, bytes32 sourceCurrencyKey, bytes32 destinationCurrencyKey) = abi.decode(
                                        bridgeData,
                                        (ISynthetix, bytes32, bytes32)
                                    );
                                    boughtAmount = exchange(synthetix, sourceCurrencyKey, destinationCurrencyKey, sellAmount);
                                }
                                function exchange(
                                    ISynthetix synthetix,
                                    bytes32 sourceCurrencyKey,
                                    bytes32 destinationCurrencyKey,
                                    uint256 sellAmount
                                ) internal returns (uint256 boughtAmount) {
                                    uint256 chainId;
                                    assembly {
                                        chainId := chainid()
                                    }
                                    if (chainId == 1) {
                                        boughtAmount = synthetix.exchangeAtomically(
                                            sourceCurrencyKey,
                                            sellAmount,
                                            destinationCurrencyKey,
                                            trackingCode,
                                            0
                                        );
                                    } else {
                                        boughtAmount = synthetix.exchangeWithTracking(
                                            sourceCurrencyKey,
                                            sellAmount,
                                            destinationCurrencyKey,
                                            rewardAddress,
                                            trackingCode
                                        );
                                    }
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "@0x/contracts-erc20/src/IEtherToken.sol";
                            import "../IBridgeAdapter.sol";
                            interface IUniswapExchangeFactory {
                                /// @dev Get the exchange for a token.
                                /// @param token The token contract.
                                function getExchange(IERC20Token token) external view returns (IUniswapExchange exchange);
                            }
                            interface IUniswapExchange {
                                /// @dev Buys at least `minTokensBought` tokens with ETH and transfer them
                                ///      to `recipient`.
                                /// @param minTokensBought The minimum number of tokens to buy.
                                /// @param deadline Time when this order expires.
                                /// @param recipient Who to transfer the tokens to.
                                /// @return tokensBought Amount of tokens bought.
                                function ethToTokenTransferInput(
                                    uint256 minTokensBought,
                                    uint256 deadline,
                                    address recipient
                                ) external payable returns (uint256 tokensBought);
                                /// @dev Buys at least `minEthBought` ETH with tokens.
                                /// @param tokensSold Amount of tokens to sell.
                                /// @param minEthBought The minimum amount of ETH to buy.
                                /// @param deadline Time when this order expires.
                                /// @return ethBought Amount of tokens bought.
                                function tokenToEthSwapInput(
                                    uint256 tokensSold,
                                    uint256 minEthBought,
                                    uint256 deadline
                                ) external returns (uint256 ethBought);
                                /// @dev Buys at least `minTokensBought` tokens with the exchange token
                                ///      and transfer them to `recipient`.
                                /// @param tokensSold Amount of tokens to sell.
                                /// @param minTokensBought The minimum number of tokens to buy.
                                /// @param minEthBought The minimum amount of intermediate ETH to buy.
                                /// @param deadline Time when this order expires.
                                /// @param recipient Who to transfer the tokens to.
                                /// @param buyToken The token being bought.
                                /// @return tokensBought Amount of tokens bought.
                                function tokenToTokenTransferInput(
                                    uint256 tokensSold,
                                    uint256 minTokensBought,
                                    uint256 minEthBought,
                                    uint256 deadline,
                                    address recipient,
                                    IERC20Token buyToken
                                ) external returns (uint256 tokensBought);
                                /// @dev Buys at least `minTokensBought` tokens with the exchange token.
                                /// @param tokensSold Amount of tokens to sell.
                                /// @param minTokensBought The minimum number of tokens to buy.
                                /// @param minEthBought The minimum amount of intermediate ETH to buy.
                                /// @param deadline Time when this order expires.
                                /// @param buyToken The token being bought.
                                /// @return tokensBought Amount of tokens bought.
                                function tokenToTokenSwapInput(
                                    uint256 tokensSold,
                                    uint256 minTokensBought,
                                    uint256 minEthBought,
                                    uint256 deadline,
                                    IERC20Token buyToken
                                ) external returns (uint256 tokensBought);
                            }
                            contract MixinUniswap {
                                using LibERC20TokenV06 for IERC20Token;
                                /// @dev Mainnet address of the WETH contract.
                                IEtherToken private immutable WETH;
                                constructor(IEtherToken weth) public {
                                    WETH = weth;
                                }
                                //B7solhint-disable-next-lineB7function-max-lines
                                function _tradeUniswap(
                                    IERC20Token sellToken,
                                    IERC20Token buyToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256 boughtAmount) {
                                    IUniswapExchangeFactory exchangeFactory = abi.decode(bridgeData, (IUniswapExchangeFactory));
                                    // Get the exchange for the token pair.
                                    IUniswapExchange exchange = _getUniswapExchangeForTokenPair(exchangeFactory, sellToken, buyToken);
                                    // Convert from WETH to a token.
                                    if (sellToken == WETH) {
                                        // Unwrap the WETH.
                                        WETH.withdraw(sellAmount);
                                        // Buy as much of `buyToken` token with ETH as possible
                                        boughtAmount = exchange.ethToTokenTransferInput{value: sellAmount}(
                                            // Minimum buy amount.
                                            1,
                                            // Expires after this block.
                                            block.timestamp,
                                            // Recipient is `this`.
                                            address(this)
                                        );
                                        // Convert from a token to WETH.
                                    } else if (buyToken == WETH) {
                                        // Grant the exchange an allowance.
                                        sellToken.approveIfBelow(address(exchange), sellAmount);
                                        // Buy as much ETH with `sellToken` token as possible.
                                        boughtAmount = exchange.tokenToEthSwapInput(
                                            // Sell all tokens we hold.
                                            sellAmount,
                                            // Minimum buy amount.
                                            1,
                                            // Expires after this block.
                                            block.timestamp
                                        );
                                        // Wrap the ETH.
                                        WETH.deposit{value: boughtAmount}();
                                        // Convert from one token to another.
                                    } else {
                                        // Grant the exchange an allowance.
                                        sellToken.approveIfBelow(address(exchange), sellAmount);
                                        // Buy as much `buyToken` token with `sellToken` token
                                        boughtAmount = exchange.tokenToTokenSwapInput(
                                            // Sell all tokens we hold.
                                            sellAmount,
                                            // Minimum buy amount.
                                            1,
                                            // Must buy at least 1 intermediate wei of ETH.
                                            1,
                                            // Expires after this block.
                                            block.timestamp,
                                            // Convert to `buyToken`.
                                            buyToken
                                        );
                                    }
                                    return boughtAmount;
                                }
                                /// @dev Retrieves the uniswap exchange for a given token pair.
                                ///      In the case of a WETH-token exchange, this will be the non-WETH token.
                                ///      In th ecase of a token-token exchange, this will be the first token.
                                /// @param exchangeFactory The exchange factory.
                                /// @param sellToken The address of the token we are converting from.
                                /// @param buyToken The address of the token we are converting to.
                                /// @return exchange The uniswap exchange.
                                function _getUniswapExchangeForTokenPair(
                                    IUniswapExchangeFactory exchangeFactory,
                                    IERC20Token sellToken,
                                    IERC20Token buyToken
                                ) private view returns (IUniswapExchange exchange) {
                                    // Whichever isn't WETH is the exchange token.
                                    exchange = sellToken == WETH ? exchangeFactory.getExchange(buyToken) : exchangeFactory.getExchange(sellToken);
                                    require(address(exchange) != address(0), "MixinUniswap/NO_EXCHANGE");
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            pragma experimental ABIEncoderV2;
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "../IBridgeAdapter.sol";
                            interface IUniswapV3Router {
                                struct ExactInputParams {
                                    bytes path;
                                    address recipient;
                                    uint256 deadline;
                                    uint256 amountIn;
                                    uint256 amountOutMinimum;
                                }
                                function exactInput(ExactInputParams memory params) external payable returns (uint256 amountOut);
                            }
                            // https://github.com/Uniswap/swap-router-contracts/blob/main/contracts/interfaces/IV3SwapRouter.sol
                            interface IUniswapV3Router2 {
                                struct ExactInputParams {
                                    bytes path;
                                    address recipient;
                                    uint256 amountIn;
                                    uint256 amountOutMinimum;
                                }
                                function exactInput(ExactInputParams memory params) external payable returns (uint256 amountOut);
                            }
                            contract MixinUniswapV3 {
                                using LibERC20TokenV06 for IERC20Token;
                                function _tradeUniswapV3(
                                    IERC20Token sellToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256 boughtAmount) {
                                    (address router, bytes memory path, uint256 routerVersion) = abi.decode(bridgeData, (address, bytes, uint256));
                                    // Grant the Uniswap router an allowance to sell the sell token.
                                    sellToken.approveIfBelow(router, sellAmount);
                                    if (routerVersion != 2) {
                                        boughtAmount = IUniswapV3Router(router).exactInput(
                                            IUniswapV3Router.ExactInputParams({
                                                path: path,
                                                recipient: address(this),
                                                deadline: block.timestamp,
                                                amountIn: sellAmount,
                                                amountOutMinimum: 1
                                            })
                                        );
                                    } else {
                                        boughtAmount = IUniswapV3Router2(router).exactInput(
                                            IUniswapV3Router2.ExactInputParams({
                                                path: path,
                                                recipient: address(this),
                                                amountIn: sellAmount,
                                                amountOutMinimum: 1
                                            })
                                        );
                                    }
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "@0x/contracts-erc20/src/v06/LibERC20TokenV06.sol";
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            import "@0x/contracts-utils/contracts/src/v06/LibSafeMathV06.sol";
                            import "../../../vendor/ILiquidityProvider.sol";
                            contract MixinZeroExBridge {
                                using LibERC20TokenV06 for IERC20Token;
                                using LibSafeMathV06 for uint256;
                                function _tradeZeroExBridge(
                                    IERC20Token sellToken,
                                    IERC20Token buyToken,
                                    uint256 sellAmount,
                                    bytes memory bridgeData
                                ) internal returns (uint256 boughtAmount) {
                                    (ILiquidityProvider provider, bytes memory lpData) = abi.decode(bridgeData, (ILiquidityProvider, bytes));
                                    // Trade the good old fashioned way
                                    sellToken.compatTransfer(address(provider), sellAmount);
                                    boughtAmount = provider.sellTokenForToken(
                                        sellToken,
                                        buyToken,
                                        address(this), // recipient
                                        1, // minBuyAmount
                                        lpData
                                    );
                                }
                            }
                            // SPDX-License-Identifier: Apache-2.0
                            /*
                              Copyright 2023 ZeroEx Intl.
                              Licensed under the Apache License, Version 2.0 (the "License");
                              you may not use this file except in compliance with the License.
                              You may obtain a copy of the License at
                                http://www.apache.org/licenses/LICENSE-2.0
                              Unless required by applicable law or agreed to in writing, software
                              distributed under the License is distributed on an "AS IS" BASIS,
                              WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                              See the License for the specific language governing permissions and
                              limitations under the License.
                            */
                            pragma solidity ^0.6.5;
                            import "@0x/contracts-erc20/src/IERC20Token.sol";
                            interface ILiquidityProvider {
                                /// @dev An optional event an LP can emit for each fill against a source.
                                /// @param inputToken The input token.
                                /// @param outputToken The output token.
                                /// @param inputTokenAmount How much input token was sold.
                                /// @param outputTokenAmount How much output token was bought.
                                /// @param sourceId A bytes32 encoded ascii source ID. E.g., `bytes32('Curve')`/
                                /// @param sourceAddress An optional address associated with the source (e.g, a curve pool).
                                /// @param sourceId A bytes32 encoded ascii source ID. E.g., `bytes32('Curve')`/
                                /// @param sourceAddress An optional address associated with the source (e.g, a curve pool).
                                /// @param sender The caller of the LP.
                                /// @param recipient The recipient of the output tokens.
                                event LiquidityProviderFill(
                                    IERC20Token inputToken,
                                    IERC20Token outputToken,
                                    uint256 inputTokenAmount,
                                    uint256 outputTokenAmount,
                                    bytes32 sourceId,
                                    address sourceAddress,
                                    address sender,
                                    address recipient
                                );
                                /// @dev Trades `inputToken` for `outputToken`. The amount of `inputToken`
                                ///      to sell must be transferred to the contract prior to calling this
                                ///      function to trigger the trade.
                                /// @param inputToken The token being sold.
                                /// @param outputToken The token being bought.
                                /// @param recipient The recipient of the bought tokens.
                                /// @param minBuyAmount The minimum acceptable amount of `outputToken` to buy.
                                /// @param auxiliaryData Arbitrary auxiliary data supplied to the contract.
                                /// @return boughtAmount The amount of `outputToken` bought.
                                function sellTokenForToken(
                                    IERC20Token inputToken,
                                    IERC20Token outputToken,
                                    address recipient,
                                    uint256 minBuyAmount,
                                    bytes calldata auxiliaryData
                                ) external returns (uint256 boughtAmount);
                                /// @dev Trades ETH for token. ETH must either be attached to this function
                                ///      call or sent to the contract prior to calling this function to
                                ///      trigger the trade.
                                /// @param outputToken The token being bought.
                                /// @param recipient The recipient of the bought tokens.
                                /// @param minBuyAmount The minimum acceptable amount of `outputToken` to buy.
                                /// @param auxiliaryData Arbitrary auxiliary data supplied to the contract.
                                /// @return boughtAmount The amount of `outputToken` bought.
                                function sellEthForToken(
                                    IERC20Token outputToken,
                                    address recipient,
                                    uint256 minBuyAmount,
                                    bytes calldata auxiliaryData
                                ) external payable returns (uint256 boughtAmount);
                                /// @dev Trades token for ETH. The token must be sent to the contract prior
                                ///      to calling this function to trigger the trade.
                                /// @param inputToken The token being sold.
                                /// @param recipient The recipient of the bought tokens.
                                /// @param minBuyAmount The minimum acceptable amount of ETH to buy.
                                /// @param auxiliaryData Arbitrary auxiliary data supplied to the contract.
                                /// @return boughtAmount The amount of ETH bought.
                                function sellTokenForEth(
                                    IERC20Token inputToken,
                                    address payable recipient,
                                    uint256 minBuyAmount,
                                    bytes calldata auxiliaryData
                                ) external returns (uint256 boughtAmount);
                                /// @dev Quotes the amount of `outputToken` that would be obtained by
                                ///      selling `sellAmount` of `inputToken`.
                                /// @param inputToken Address of the taker token (what to sell). Use
                                ///        the wETH address if selling ETH.
                                /// @param outputToken Address of the maker token (what to buy). Use
                                ///        the wETH address if buying ETH.
                                /// @param sellAmount Amount of `inputToken` to sell.
                                /// @return outputTokenAmount Amount of `outputToken` that would be obtained.
                                function getSellQuote(
                                    IERC20Token inputToken,
                                    IERC20Token outputToken,
                                    uint256 sellAmount
                                ) external view returns (uint256 outputTokenAmount);
                            }
                            

                            File 8 of 9: UniswapV2Router01
                            // File: @uniswap/v2-core/contracts/interfaces/IUniswapV2Factory.sol
                            
                            pragma solidity >=0.5.0;
                            
                            interface IUniswapV2Factory {
                                event PairCreated(address indexed token0, address indexed token1, address pair, uint);
                            
                                function feeTo() external view returns (address);
                                function feeToSetter() external view returns (address);
                            
                                function getPair(address tokenA, address tokenB) external view returns (address pair);
                                function allPairs(uint) external view returns (address pair);
                                function allPairsLength() external view returns (uint);
                            
                                function createPair(address tokenA, address tokenB) external returns (address pair);
                            
                                function setFeeTo(address) external;
                                function setFeeToSetter(address) external;
                            }
                            
                            // File: @uniswap/lib/contracts/libraries/TransferHelper.sol
                            
                            pragma solidity >=0.6.0;
                            
                            // helper methods for interacting with ERC20 tokens and sending ETH that do not consistently return true/false
                            library TransferHelper {
                                function safeApprove(address token, address to, uint value) internal {
                                    // bytes4(keccak256(bytes('approve(address,uint256)')));
                                    (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x095ea7b3, to, value));
                                    require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: APPROVE_FAILED');
                                }
                            
                                function safeTransfer(address token, address to, uint value) internal {
                                    // bytes4(keccak256(bytes('transfer(address,uint256)')));
                                    (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0xa9059cbb, to, value));
                                    require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FAILED');
                                }
                            
                                function safeTransferFrom(address token, address from, address to, uint value) internal {
                                    // bytes4(keccak256(bytes('transferFrom(address,address,uint256)')));
                                    (bool success, bytes memory data) = token.call(abi.encodeWithSelector(0x23b872dd, from, to, value));
                                    require(success && (data.length == 0 || abi.decode(data, (bool))), 'TransferHelper: TRANSFER_FROM_FAILED');
                                }
                            
                                function safeTransferETH(address to, uint value) internal {
                                    (bool success,) = to.call{value:value}(new bytes(0));
                                    require(success, 'TransferHelper: ETH_TRANSFER_FAILED');
                                }
                            }
                            
                            // File: @uniswap/v2-core/contracts/interfaces/IUniswapV2Pair.sol
                            
                            pragma solidity >=0.5.0;
                            
                            interface IUniswapV2Pair {
                                event Approval(address indexed owner, address indexed spender, uint value);
                                event Transfer(address indexed from, address indexed to, uint value);
                            
                                function name() external pure returns (string memory);
                                function symbol() external pure returns (string memory);
                                function decimals() external pure returns (uint8);
                                function totalSupply() external view returns (uint);
                                function balanceOf(address owner) external view returns (uint);
                                function allowance(address owner, address spender) external view returns (uint);
                            
                                function approve(address spender, uint value) external returns (bool);
                                function transfer(address to, uint value) external returns (bool);
                                function transferFrom(address from, address to, uint value) external returns (bool);
                            
                                function DOMAIN_SEPARATOR() external view returns (bytes32);
                                function PERMIT_TYPEHASH() external pure returns (bytes32);
                                function nonces(address owner) external view returns (uint);
                            
                                function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;
                            
                                event Mint(address indexed sender, uint amount0, uint amount1);
                                event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
                                event Swap(
                                    address indexed sender,
                                    uint amount0In,
                                    uint amount1In,
                                    uint amount0Out,
                                    uint amount1Out,
                                    address indexed to
                                );
                                event Sync(uint112 reserve0, uint112 reserve1);
                            
                                function MINIMUM_LIQUIDITY() external pure returns (uint);
                                function factory() external view returns (address);
                                function token0() external view returns (address);
                                function token1() external view returns (address);
                                function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
                                function price0CumulativeLast() external view returns (uint);
                                function price1CumulativeLast() external view returns (uint);
                                function kLast() external view returns (uint);
                            
                                function mint(address to) external returns (uint liquidity);
                                function burn(address to) external returns (uint amount0, uint amount1);
                                function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
                                function skim(address to) external;
                                function sync() external;
                            
                                function initialize(address, address) external;
                            }
                            
                            // File: contracts/libraries/SafeMath.sol
                            
                            pragma solidity =0.6.6;
                            
                            // a library for performing overflow-safe math, courtesy of DappHub (https://github.com/dapphub/ds-math)
                            
                            library SafeMath {
                                function add(uint x, uint y) internal pure returns (uint z) {
                                    require((z = x + y) >= x, 'ds-math-add-overflow');
                                }
                            
                                function sub(uint x, uint y) internal pure returns (uint z) {
                                    require((z = x - y) <= x, 'ds-math-sub-underflow');
                                }
                            
                                function mul(uint x, uint y) internal pure returns (uint z) {
                                    require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');
                                }
                            }
                            
                            // File: contracts/libraries/UniswapV2Library.sol
                            
                            pragma solidity >=0.5.0;
                            
                            
                            
                            library UniswapV2Library {
                                using SafeMath for uint;
                            
                                // returns sorted token addresses, used to handle return values from pairs sorted in this order
                                function sortTokens(address tokenA, address tokenB) internal pure returns (address token0, address token1) {
                                    require(tokenA != tokenB, 'UniswapV2Library: IDENTICAL_ADDRESSES');
                                    (token0, token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
                                    require(token0 != address(0), 'UniswapV2Library: ZERO_ADDRESS');
                                }
                            
                                // calculates the CREATE2 address for a pair without making any external calls
                                function pairFor(address factory, address tokenA, address tokenB) internal pure returns (address pair) {
                                    (address token0, address token1) = sortTokens(tokenA, tokenB);
                                    pair = address(uint(keccak256(abi.encodePacked(
                                            hex'ff',
                                            factory,
                                            keccak256(abi.encodePacked(token0, token1)),
                                            hex'96e8ac4277198ff8b6f785478aa9a39f403cb768dd02cbee326c3e7da348845f' // init code hash
                                        ))));
                                }
                            
                                // fetches and sorts the reserves for a pair
                                function getReserves(address factory, address tokenA, address tokenB) internal view returns (uint reserveA, uint reserveB) {
                                    (address token0,) = sortTokens(tokenA, tokenB);
                                    (uint reserve0, uint reserve1,) = IUniswapV2Pair(pairFor(factory, tokenA, tokenB)).getReserves();
                                    (reserveA, reserveB) = tokenA == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
                                }
                            
                                // given some amount of an asset and pair reserves, returns an equivalent amount of the other asset
                                function quote(uint amountA, uint reserveA, uint reserveB) internal pure returns (uint amountB) {
                                    require(amountA > 0, 'UniswapV2Library: INSUFFICIENT_AMOUNT');
                                    require(reserveA > 0 && reserveB > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
                                    amountB = amountA.mul(reserveB) / reserveA;
                                }
                            
                                // given an input amount of an asset and pair reserves, returns the maximum output amount of the other asset
                                function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) internal pure returns (uint amountOut) {
                                    require(amountIn > 0, 'UniswapV2Library: INSUFFICIENT_INPUT_AMOUNT');
                                    require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
                                    uint amountInWithFee = amountIn.mul(997);
                                    uint numerator = amountInWithFee.mul(reserveOut);
                                    uint denominator = reserveIn.mul(1000).add(amountInWithFee);
                                    amountOut = numerator / denominator;
                                }
                            
                                // given an output amount of an asset and pair reserves, returns a required input amount of the other asset
                                function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) internal pure returns (uint amountIn) {
                                    require(amountOut > 0, 'UniswapV2Library: INSUFFICIENT_OUTPUT_AMOUNT');
                                    require(reserveIn > 0 && reserveOut > 0, 'UniswapV2Library: INSUFFICIENT_LIQUIDITY');
                                    uint numerator = reserveIn.mul(amountOut).mul(1000);
                                    uint denominator = reserveOut.sub(amountOut).mul(997);
                                    amountIn = (numerator / denominator).add(1);
                                }
                            
                                // performs chained getAmountOut calculations on any number of pairs
                                function getAmountsOut(address factory, uint amountIn, address[] memory path) internal view returns (uint[] memory amounts) {
                                    require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');
                                    amounts = new uint[](path.length);
                                    amounts[0] = amountIn;
                                    for (uint i; i < path.length - 1; i++) {
                                        (uint reserveIn, uint reserveOut) = getReserves(factory, path[i], path[i + 1]);
                                        amounts[i + 1] = getAmountOut(amounts[i], reserveIn, reserveOut);
                                    }
                                }
                            
                                // performs chained getAmountIn calculations on any number of pairs
                                function getAmountsIn(address factory, uint amountOut, address[] memory path) internal view returns (uint[] memory amounts) {
                                    require(path.length >= 2, 'UniswapV2Library: INVALID_PATH');
                                    amounts = new uint[](path.length);
                                    amounts[amounts.length - 1] = amountOut;
                                    for (uint i = path.length - 1; i > 0; i--) {
                                        (uint reserveIn, uint reserveOut) = getReserves(factory, path[i - 1], path[i]);
                                        amounts[i - 1] = getAmountIn(amounts[i], reserveIn, reserveOut);
                                    }
                                }
                            }
                            
                            // File: contracts/interfaces/IUniswapV2Router01.sol
                            
                            pragma solidity >=0.6.2;
                            
                            interface IUniswapV2Router01 {
                                function factory() external pure returns (address);
                                function WETH() external pure returns (address);
                            
                                function addLiquidity(
                                    address tokenA,
                                    address tokenB,
                                    uint amountADesired,
                                    uint amountBDesired,
                                    uint amountAMin,
                                    uint amountBMin,
                                    address to,
                                    uint deadline
                                ) external returns (uint amountA, uint amountB, uint liquidity);
                                function addLiquidityETH(
                                    address token,
                                    uint amountTokenDesired,
                                    uint amountTokenMin,
                                    uint amountETHMin,
                                    address to,
                                    uint deadline
                                ) external payable returns (uint amountToken, uint amountETH, uint liquidity);
                                function removeLiquidity(
                                    address tokenA,
                                    address tokenB,
                                    uint liquidity,
                                    uint amountAMin,
                                    uint amountBMin,
                                    address to,
                                    uint deadline
                                ) external returns (uint amountA, uint amountB);
                                function removeLiquidityETH(
                                    address token,
                                    uint liquidity,
                                    uint amountTokenMin,
                                    uint amountETHMin,
                                    address to,
                                    uint deadline
                                ) external returns (uint amountToken, uint amountETH);
                                function removeLiquidityWithPermit(
                                    address tokenA,
                                    address tokenB,
                                    uint liquidity,
                                    uint amountAMin,
                                    uint amountBMin,
                                    address to,
                                    uint deadline,
                                    bool approveMax, uint8 v, bytes32 r, bytes32 s
                                ) external returns (uint amountA, uint amountB);
                                function removeLiquidityETHWithPermit(
                                    address token,
                                    uint liquidity,
                                    uint amountTokenMin,
                                    uint amountETHMin,
                                    address to,
                                    uint deadline,
                                    bool approveMax, uint8 v, bytes32 r, bytes32 s
                                ) external returns (uint amountToken, uint amountETH);
                                function swapExactTokensForTokens(
                                    uint amountIn,
                                    uint amountOutMin,
                                    address[] calldata path,
                                    address to,
                                    uint deadline
                                ) external returns (uint[] memory amounts);
                                function swapTokensForExactTokens(
                                    uint amountOut,
                                    uint amountInMax,
                                    address[] calldata path,
                                    address to,
                                    uint deadline
                                ) external returns (uint[] memory amounts);
                                function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
                                    external
                                    payable
                                    returns (uint[] memory amounts);
                                function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
                                    external
                                    returns (uint[] memory amounts);
                                function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
                                    external
                                    returns (uint[] memory amounts);
                                function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
                                    external
                                    payable
                                    returns (uint[] memory amounts);
                            
                                function quote(uint amountA, uint reserveA, uint reserveB) external pure returns (uint amountB);
                                function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);
                                function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) external pure returns (uint amountIn);
                                function getAmountsOut(uint amountIn, address[] calldata path) external view returns (uint[] memory amounts);
                                function getAmountsIn(uint amountOut, address[] calldata path) external view returns (uint[] memory amounts);
                            }
                            
                            // File: contracts/interfaces/IERC20.sol
                            
                            pragma solidity >=0.5.0;
                            
                            interface IERC20 {
                                event Approval(address indexed owner, address indexed spender, uint value);
                                event Transfer(address indexed from, address indexed to, uint value);
                            
                                function name() external view returns (string memory);
                                function symbol() external view returns (string memory);
                                function decimals() external view returns (uint8);
                                function totalSupply() external view returns (uint);
                                function balanceOf(address owner) external view returns (uint);
                                function allowance(address owner, address spender) external view returns (uint);
                            
                                function approve(address spender, uint value) external returns (bool);
                                function transfer(address to, uint value) external returns (bool);
                                function transferFrom(address from, address to, uint value) external returns (bool);
                            }
                            
                            // File: contracts/interfaces/IWETH.sol
                            
                            pragma solidity >=0.5.0;
                            
                            interface IWETH {
                                function deposit() external payable;
                                function transfer(address to, uint value) external returns (bool);
                                function withdraw(uint) external;
                            }
                            
                            // File: contracts/UniswapV2Router01.sol
                            
                            pragma solidity =0.6.6;
                            
                            
                            
                            
                            
                            
                            
                            contract UniswapV2Router01 is IUniswapV2Router01 {
                                address public immutable override factory;
                                address public immutable override WETH;
                            
                                modifier ensure(uint deadline) {
                                    require(deadline >= block.timestamp, 'UniswapV2Router: EXPIRED');
                                    _;
                                }
                            
                                constructor(address _factory, address _WETH) public {
                                    factory = _factory;
                                    WETH = _WETH;
                                }
                            
                                receive() external payable {
                                    assert(msg.sender == WETH); // only accept ETH via fallback from the WETH contract
                                }
                            
                                // **** ADD LIQUIDITY ****
                                function _addLiquidity(
                                    address tokenA,
                                    address tokenB,
                                    uint amountADesired,
                                    uint amountBDesired,
                                    uint amountAMin,
                                    uint amountBMin
                                ) private returns (uint amountA, uint amountB) {
                                    // create the pair if it doesn't exist yet
                                    if (IUniswapV2Factory(factory).getPair(tokenA, tokenB) == address(0)) {
                                        IUniswapV2Factory(factory).createPair(tokenA, tokenB);
                                    }
                                    (uint reserveA, uint reserveB) = UniswapV2Library.getReserves(factory, tokenA, tokenB);
                                    if (reserveA == 0 && reserveB == 0) {
                                        (amountA, amountB) = (amountADesired, amountBDesired);
                                    } else {
                                        uint amountBOptimal = UniswapV2Library.quote(amountADesired, reserveA, reserveB);
                                        if (amountBOptimal <= amountBDesired) {
                                            require(amountBOptimal >= amountBMin, 'UniswapV2Router: INSUFFICIENT_B_AMOUNT');
                                            (amountA, amountB) = (amountADesired, amountBOptimal);
                                        } else {
                                            uint amountAOptimal = UniswapV2Library.quote(amountBDesired, reserveB, reserveA);
                                            assert(amountAOptimal <= amountADesired);
                                            require(amountAOptimal >= amountAMin, 'UniswapV2Router: INSUFFICIENT_A_AMOUNT');
                                            (amountA, amountB) = (amountAOptimal, amountBDesired);
                                        }
                                    }
                                }
                                function addLiquidity(
                                    address tokenA,
                                    address tokenB,
                                    uint amountADesired,
                                    uint amountBDesired,
                                    uint amountAMin,
                                    uint amountBMin,
                                    address to,
                                    uint deadline
                                ) external override ensure(deadline) returns (uint amountA, uint amountB, uint liquidity) {
                                    (amountA, amountB) = _addLiquidity(tokenA, tokenB, amountADesired, amountBDesired, amountAMin, amountBMin);
                                    address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);
                                    TransferHelper.safeTransferFrom(tokenA, msg.sender, pair, amountA);
                                    TransferHelper.safeTransferFrom(tokenB, msg.sender, pair, amountB);
                                    liquidity = IUniswapV2Pair(pair).mint(to);
                                }
                                function addLiquidityETH(
                                    address token,
                                    uint amountTokenDesired,
                                    uint amountTokenMin,
                                    uint amountETHMin,
                                    address to,
                                    uint deadline
                                ) external override payable ensure(deadline) returns (uint amountToken, uint amountETH, uint liquidity) {
                                    (amountToken, amountETH) = _addLiquidity(
                                        token,
                                        WETH,
                                        amountTokenDesired,
                                        msg.value,
                                        amountTokenMin,
                                        amountETHMin
                                    );
                                    address pair = UniswapV2Library.pairFor(factory, token, WETH);
                                    TransferHelper.safeTransferFrom(token, msg.sender, pair, amountToken);
                                    IWETH(WETH).deposit{value: amountETH}();
                                    assert(IWETH(WETH).transfer(pair, amountETH));
                                    liquidity = IUniswapV2Pair(pair).mint(to);
                                    if (msg.value > amountETH) TransferHelper.safeTransferETH(msg.sender, msg.value - amountETH); // refund dust eth, if any
                                }
                            
                                // **** REMOVE LIQUIDITY ****
                                function removeLiquidity(
                                    address tokenA,
                                    address tokenB,
                                    uint liquidity,
                                    uint amountAMin,
                                    uint amountBMin,
                                    address to,
                                    uint deadline
                                ) public override ensure(deadline) returns (uint amountA, uint amountB) {
                                    address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);
                                    IUniswapV2Pair(pair).transferFrom(msg.sender, pair, liquidity); // send liquidity to pair
                                    (uint amount0, uint amount1) = IUniswapV2Pair(pair).burn(to);
                                    (address token0,) = UniswapV2Library.sortTokens(tokenA, tokenB);
                                    (amountA, amountB) = tokenA == token0 ? (amount0, amount1) : (amount1, amount0);
                                    require(amountA >= amountAMin, 'UniswapV2Router: INSUFFICIENT_A_AMOUNT');
                                    require(amountB >= amountBMin, 'UniswapV2Router: INSUFFICIENT_B_AMOUNT');
                                }
                                function removeLiquidityETH(
                                    address token,
                                    uint liquidity,
                                    uint amountTokenMin,
                                    uint amountETHMin,
                                    address to,
                                    uint deadline
                                ) public override ensure(deadline) returns (uint amountToken, uint amountETH) {
                                    (amountToken, amountETH) = removeLiquidity(
                                        token,
                                        WETH,
                                        liquidity,
                                        amountTokenMin,
                                        amountETHMin,
                                        address(this),
                                        deadline
                                    );
                                    TransferHelper.safeTransfer(token, to, amountToken);
                                    IWETH(WETH).withdraw(amountETH);
                                    TransferHelper.safeTransferETH(to, amountETH);
                                }
                                function removeLiquidityWithPermit(
                                    address tokenA,
                                    address tokenB,
                                    uint liquidity,
                                    uint amountAMin,
                                    uint amountBMin,
                                    address to,
                                    uint deadline,
                                    bool approveMax, uint8 v, bytes32 r, bytes32 s
                                ) external override returns (uint amountA, uint amountB) {
                                    address pair = UniswapV2Library.pairFor(factory, tokenA, tokenB);
                                    uint value = approveMax ? uint(-1) : liquidity;
                                    IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
                                    (amountA, amountB) = removeLiquidity(tokenA, tokenB, liquidity, amountAMin, amountBMin, to, deadline);
                                }
                                function removeLiquidityETHWithPermit(
                                    address token,
                                    uint liquidity,
                                    uint amountTokenMin,
                                    uint amountETHMin,
                                    address to,
                                    uint deadline,
                                    bool approveMax, uint8 v, bytes32 r, bytes32 s
                                ) external override returns (uint amountToken, uint amountETH) {
                                    address pair = UniswapV2Library.pairFor(factory, token, WETH);
                                    uint value = approveMax ? uint(-1) : liquidity;
                                    IUniswapV2Pair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
                                    (amountToken, amountETH) = removeLiquidityETH(token, liquidity, amountTokenMin, amountETHMin, to, deadline);
                                }
                            
                                // **** SWAP ****
                                // requires the initial amount to have already been sent to the first pair
                                function _swap(uint[] memory amounts, address[] memory path, address _to) private {
                                    for (uint i; i < path.length - 1; i++) {
                                        (address input, address output) = (path[i], path[i + 1]);
                                        (address token0,) = UniswapV2Library.sortTokens(input, output);
                                        uint amountOut = amounts[i + 1];
                                        (uint amount0Out, uint amount1Out) = input == token0 ? (uint(0), amountOut) : (amountOut, uint(0));
                                        address to = i < path.length - 2 ? UniswapV2Library.pairFor(factory, output, path[i + 2]) : _to;
                                        IUniswapV2Pair(UniswapV2Library.pairFor(factory, input, output)).swap(amount0Out, amount1Out, to, new bytes(0));
                                    }
                                }
                                function swapExactTokensForTokens(
                                    uint amountIn,
                                    uint amountOutMin,
                                    address[] calldata path,
                                    address to,
                                    uint deadline
                                ) external override ensure(deadline) returns (uint[] memory amounts) {
                                    amounts = UniswapV2Library.getAmountsOut(factory, amountIn, path);
                                    require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');
                                    TransferHelper.safeTransferFrom(path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]);
                                    _swap(amounts, path, to);
                                }
                                function swapTokensForExactTokens(
                                    uint amountOut,
                                    uint amountInMax,
                                    address[] calldata path,
                                    address to,
                                    uint deadline
                                ) external override ensure(deadline) returns (uint[] memory amounts) {
                                    amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);
                                    require(amounts[0] <= amountInMax, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');
                                    TransferHelper.safeTransferFrom(path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]);
                                    _swap(amounts, path, to);
                                }
                                function swapExactETHForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
                                    external
                                    override
                                    payable
                                    ensure(deadline)
                                    returns (uint[] memory amounts)
                                {
                                    require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');
                                    amounts = UniswapV2Library.getAmountsOut(factory, msg.value, path);
                                    require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');
                                    IWETH(WETH).deposit{value: amounts[0]}();
                                    assert(IWETH(WETH).transfer(UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]));
                                    _swap(amounts, path, to);
                                }
                                function swapTokensForExactETH(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
                                    external
                                    override
                                    ensure(deadline)
                                    returns (uint[] memory amounts)
                                {
                                    require(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');
                                    amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);
                                    require(amounts[0] <= amountInMax, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');
                                    TransferHelper.safeTransferFrom(path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]);
                                    _swap(amounts, path, address(this));
                                    IWETH(WETH).withdraw(amounts[amounts.length - 1]);
                                    TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);
                                }
                                function swapExactTokensForETH(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
                                    external
                                    override
                                    ensure(deadline)
                                    returns (uint[] memory amounts)
                                {
                                    require(path[path.length - 1] == WETH, 'UniswapV2Router: INVALID_PATH');
                                    amounts = UniswapV2Library.getAmountsOut(factory, amountIn, path);
                                    require(amounts[amounts.length - 1] >= amountOutMin, 'UniswapV2Router: INSUFFICIENT_OUTPUT_AMOUNT');
                                    TransferHelper.safeTransferFrom(path[0], msg.sender, UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]);
                                    _swap(amounts, path, address(this));
                                    IWETH(WETH).withdraw(amounts[amounts.length - 1]);
                                    TransferHelper.safeTransferETH(to, amounts[amounts.length - 1]);
                                }
                                function swapETHForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
                                    external
                                    override
                                    payable
                                    ensure(deadline)
                                    returns (uint[] memory amounts)
                                {
                                    require(path[0] == WETH, 'UniswapV2Router: INVALID_PATH');
                                    amounts = UniswapV2Library.getAmountsIn(factory, amountOut, path);
                                    require(amounts[0] <= msg.value, 'UniswapV2Router: EXCESSIVE_INPUT_AMOUNT');
                                    IWETH(WETH).deposit{value: amounts[0]}();
                                    assert(IWETH(WETH).transfer(UniswapV2Library.pairFor(factory, path[0], path[1]), amounts[0]));
                                    _swap(amounts, path, to);
                                    if (msg.value > amounts[0]) TransferHelper.safeTransferETH(msg.sender, msg.value - amounts[0]); // refund dust eth, if any
                                }
                            
                                function quote(uint amountA, uint reserveA, uint reserveB) public pure override returns (uint amountB) {
                                    return UniswapV2Library.quote(amountA, reserveA, reserveB);
                                }
                            
                                function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) public pure override returns (uint amountOut) {
                                    return UniswapV2Library.getAmountOut(amountIn, reserveIn, reserveOut);
                                }
                            
                                function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut) public pure override returns (uint amountIn) {
                                    return UniswapV2Library.getAmountOut(amountOut, reserveIn, reserveOut);
                                }
                            
                                function getAmountsOut(uint amountIn, address[] memory path) public view override returns (uint[] memory amounts) {
                                    return UniswapV2Library.getAmountsOut(factory, amountIn, path);
                                }
                            
                                function getAmountsIn(uint amountOut, address[] memory path) public view override returns (uint[] memory amounts) {
                                    return UniswapV2Library.getAmountsIn(factory, amountOut, path);
                                }
                            }

                            File 9 of 9: UniswapV2Pair
                            // File: contracts/interfaces/IUniswapV2Pair.sol
                            
                            pragma solidity >=0.5.0;
                            
                            interface IUniswapV2Pair {
                                event Approval(address indexed owner, address indexed spender, uint value);
                                event Transfer(address indexed from, address indexed to, uint value);
                            
                                function name() external pure returns (string memory);
                                function symbol() external pure returns (string memory);
                                function decimals() external pure returns (uint8);
                                function totalSupply() external view returns (uint);
                                function balanceOf(address owner) external view returns (uint);
                                function allowance(address owner, address spender) external view returns (uint);
                            
                                function approve(address spender, uint value) external returns (bool);
                                function transfer(address to, uint value) external returns (bool);
                                function transferFrom(address from, address to, uint value) external returns (bool);
                            
                                function DOMAIN_SEPARATOR() external view returns (bytes32);
                                function PERMIT_TYPEHASH() external pure returns (bytes32);
                                function nonces(address owner) external view returns (uint);
                            
                                function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;
                            
                                event Mint(address indexed sender, uint amount0, uint amount1);
                                event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
                                event Swap(
                                    address indexed sender,
                                    uint amount0In,
                                    uint amount1In,
                                    uint amount0Out,
                                    uint amount1Out,
                                    address indexed to
                                );
                                event Sync(uint112 reserve0, uint112 reserve1);
                            
                                function MINIMUM_LIQUIDITY() external pure returns (uint);
                                function factory() external view returns (address);
                                function token0() external view returns (address);
                                function token1() external view returns (address);
                                function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
                                function price0CumulativeLast() external view returns (uint);
                                function price1CumulativeLast() external view returns (uint);
                                function kLast() external view returns (uint);
                            
                                function mint(address to) external returns (uint liquidity);
                                function burn(address to) external returns (uint amount0, uint amount1);
                                function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external;
                                function skim(address to) external;
                                function sync() external;
                            
                                function initialize(address, address) external;
                            }
                            
                            // File: contracts/interfaces/IUniswapV2ERC20.sol
                            
                            pragma solidity >=0.5.0;
                            
                            interface IUniswapV2ERC20 {
                                event Approval(address indexed owner, address indexed spender, uint value);
                                event Transfer(address indexed from, address indexed to, uint value);
                            
                                function name() external pure returns (string memory);
                                function symbol() external pure returns (string memory);
                                function decimals() external pure returns (uint8);
                                function totalSupply() external view returns (uint);
                                function balanceOf(address owner) external view returns (uint);
                                function allowance(address owner, address spender) external view returns (uint);
                            
                                function approve(address spender, uint value) external returns (bool);
                                function transfer(address to, uint value) external returns (bool);
                                function transferFrom(address from, address to, uint value) external returns (bool);
                            
                                function DOMAIN_SEPARATOR() external view returns (bytes32);
                                function PERMIT_TYPEHASH() external pure returns (bytes32);
                                function nonces(address owner) external view returns (uint);
                            
                                function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;
                            }
                            
                            // File: contracts/libraries/SafeMath.sol
                            
                            pragma solidity =0.5.16;
                            
                            // a library for performing overflow-safe math, courtesy of DappHub (https://github.com/dapphub/ds-math)
                            
                            library SafeMath {
                                function add(uint x, uint y) internal pure returns (uint z) {
                                    require((z = x + y) >= x, 'ds-math-add-overflow');
                                }
                            
                                function sub(uint x, uint y) internal pure returns (uint z) {
                                    require((z = x - y) <= x, 'ds-math-sub-underflow');
                                }
                            
                                function mul(uint x, uint y) internal pure returns (uint z) {
                                    require(y == 0 || (z = x * y) / y == x, 'ds-math-mul-overflow');
                                }
                            }
                            
                            // File: contracts/UniswapV2ERC20.sol
                            
                            pragma solidity =0.5.16;
                            
                            
                            
                            contract UniswapV2ERC20 is IUniswapV2ERC20 {
                                using SafeMath for uint;
                            
                                string public constant name = 'Uniswap V2';
                                string public constant symbol = 'UNI-V2';
                                uint8 public constant decimals = 18;
                                uint  public totalSupply;
                                mapping(address => uint) public balanceOf;
                                mapping(address => mapping(address => uint)) public allowance;
                            
                                bytes32 public DOMAIN_SEPARATOR;
                                // keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
                                bytes32 public constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
                                mapping(address => uint) public nonces;
                            
                                event Approval(address indexed owner, address indexed spender, uint value);
                                event Transfer(address indexed from, address indexed to, uint value);
                            
                                constructor() public {
                                    uint chainId;
                                    assembly {
                                        chainId := chainid
                                    }
                                    DOMAIN_SEPARATOR = keccak256(
                                        abi.encode(
                                            keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)'),
                                            keccak256(bytes(name)),
                                            keccak256(bytes('1')),
                                            chainId,
                                            address(this)
                                        )
                                    );
                                }
                            
                                function _mint(address to, uint value) internal {
                                    totalSupply = totalSupply.add(value);
                                    balanceOf[to] = balanceOf[to].add(value);
                                    emit Transfer(address(0), to, value);
                                }
                            
                                function _burn(address from, uint value) internal {
                                    balanceOf[from] = balanceOf[from].sub(value);
                                    totalSupply = totalSupply.sub(value);
                                    emit Transfer(from, address(0), value);
                                }
                            
                                function _approve(address owner, address spender, uint value) private {
                                    allowance[owner][spender] = value;
                                    emit Approval(owner, spender, value);
                                }
                            
                                function _transfer(address from, address to, uint value) private {
                                    balanceOf[from] = balanceOf[from].sub(value);
                                    balanceOf[to] = balanceOf[to].add(value);
                                    emit Transfer(from, to, value);
                                }
                            
                                function approve(address spender, uint value) external returns (bool) {
                                    _approve(msg.sender, spender, value);
                                    return true;
                                }
                            
                                function transfer(address to, uint value) external returns (bool) {
                                    _transfer(msg.sender, to, value);
                                    return true;
                                }
                            
                                function transferFrom(address from, address to, uint value) external returns (bool) {
                                    if (allowance[from][msg.sender] != uint(-1)) {
                                        allowance[from][msg.sender] = allowance[from][msg.sender].sub(value);
                                    }
                                    _transfer(from, to, value);
                                    return true;
                                }
                            
                                function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external {
                                    require(deadline >= block.timestamp, 'UniswapV2: EXPIRED');
                                    bytes32 digest = keccak256(
                                        abi.encodePacked(
                                            '\x19\x01',
                                            DOMAIN_SEPARATOR,
                                            keccak256(abi.encode(PERMIT_TYPEHASH, owner, spender, value, nonces[owner]++, deadline))
                                        )
                                    );
                                    address recoveredAddress = ecrecover(digest, v, r, s);
                                    require(recoveredAddress != address(0) && recoveredAddress == owner, 'UniswapV2: INVALID_SIGNATURE');
                                    _approve(owner, spender, value);
                                }
                            }
                            
                            // File: contracts/libraries/Math.sol
                            
                            pragma solidity =0.5.16;
                            
                            // a library for performing various math operations
                            
                            library Math {
                                function min(uint x, uint y) internal pure returns (uint z) {
                                    z = x < y ? x : y;
                                }
                            
                                // babylonian method (https://en.wikipedia.org/wiki/Methods_of_computing_square_roots#Babylonian_method)
                                function sqrt(uint y) internal pure returns (uint z) {
                                    if (y > 3) {
                                        z = y;
                                        uint x = y / 2 + 1;
                                        while (x < z) {
                                            z = x;
                                            x = (y / x + x) / 2;
                                        }
                                    } else if (y != 0) {
                                        z = 1;
                                    }
                                }
                            }
                            
                            // File: contracts/libraries/UQ112x112.sol
                            
                            pragma solidity =0.5.16;
                            
                            // a library for handling binary fixed point numbers (https://en.wikipedia.org/wiki/Q_(number_format))
                            
                            // range: [0, 2**112 - 1]
                            // resolution: 1 / 2**112
                            
                            library UQ112x112 {
                                uint224 constant Q112 = 2**112;
                            
                                // encode a uint112 as a UQ112x112
                                function encode(uint112 y) internal pure returns (uint224 z) {
                                    z = uint224(y) * Q112; // never overflows
                                }
                            
                                // divide a UQ112x112 by a uint112, returning a UQ112x112
                                function uqdiv(uint224 x, uint112 y) internal pure returns (uint224 z) {
                                    z = x / uint224(y);
                                }
                            }
                            
                            // File: contracts/interfaces/IERC20.sol
                            
                            pragma solidity >=0.5.0;
                            
                            interface IERC20 {
                                event Approval(address indexed owner, address indexed spender, uint value);
                                event Transfer(address indexed from, address indexed to, uint value);
                            
                                function name() external view returns (string memory);
                                function symbol() external view returns (string memory);
                                function decimals() external view returns (uint8);
                                function totalSupply() external view returns (uint);
                                function balanceOf(address owner) external view returns (uint);
                                function allowance(address owner, address spender) external view returns (uint);
                            
                                function approve(address spender, uint value) external returns (bool);
                                function transfer(address to, uint value) external returns (bool);
                                function transferFrom(address from, address to, uint value) external returns (bool);
                            }
                            
                            // File: contracts/interfaces/IUniswapV2Factory.sol
                            
                            pragma solidity >=0.5.0;
                            
                            interface IUniswapV2Factory {
                                event PairCreated(address indexed token0, address indexed token1, address pair, uint);
                            
                                function feeTo() external view returns (address);
                                function feeToSetter() external view returns (address);
                            
                                function getPair(address tokenA, address tokenB) external view returns (address pair);
                                function allPairs(uint) external view returns (address pair);
                                function allPairsLength() external view returns (uint);
                            
                                function createPair(address tokenA, address tokenB) external returns (address pair);
                            
                                function setFeeTo(address) external;
                                function setFeeToSetter(address) external;
                            }
                            
                            // File: contracts/interfaces/IUniswapV2Callee.sol
                            
                            pragma solidity >=0.5.0;
                            
                            interface IUniswapV2Callee {
                                function uniswapV2Call(address sender, uint amount0, uint amount1, bytes calldata data) external;
                            }
                            
                            // File: contracts/UniswapV2Pair.sol
                            
                            pragma solidity =0.5.16;
                            
                            
                            
                            
                            
                            
                            
                            
                            contract UniswapV2Pair is IUniswapV2Pair, UniswapV2ERC20 {
                                using SafeMath  for uint;
                                using UQ112x112 for uint224;
                            
                                uint public constant MINIMUM_LIQUIDITY = 10**3;
                                bytes4 private constant SELECTOR = bytes4(keccak256(bytes('transfer(address,uint256)')));
                            
                                address public factory;
                                address public token0;
                                address public token1;
                            
                                uint112 private reserve0;           // uses single storage slot, accessible via getReserves
                                uint112 private reserve1;           // uses single storage slot, accessible via getReserves
                                uint32  private blockTimestampLast; // uses single storage slot, accessible via getReserves
                            
                                uint public price0CumulativeLast;
                                uint public price1CumulativeLast;
                                uint public kLast; // reserve0 * reserve1, as of immediately after the most recent liquidity event
                            
                                uint private unlocked = 1;
                                modifier lock() {
                                    require(unlocked == 1, 'UniswapV2: LOCKED');
                                    unlocked = 0;
                                    _;
                                    unlocked = 1;
                                }
                            
                                function getReserves() public view returns (uint112 _reserve0, uint112 _reserve1, uint32 _blockTimestampLast) {
                                    _reserve0 = reserve0;
                                    _reserve1 = reserve1;
                                    _blockTimestampLast = blockTimestampLast;
                                }
                            
                                function _safeTransfer(address token, address to, uint value) private {
                                    (bool success, bytes memory data) = token.call(abi.encodeWithSelector(SELECTOR, to, value));
                                    require(success && (data.length == 0 || abi.decode(data, (bool))), 'UniswapV2: TRANSFER_FAILED');
                                }
                            
                                event Mint(address indexed sender, uint amount0, uint amount1);
                                event Burn(address indexed sender, uint amount0, uint amount1, address indexed to);
                                event Swap(
                                    address indexed sender,
                                    uint amount0In,
                                    uint amount1In,
                                    uint amount0Out,
                                    uint amount1Out,
                                    address indexed to
                                );
                                event Sync(uint112 reserve0, uint112 reserve1);
                            
                                constructor() public {
                                    factory = msg.sender;
                                }
                            
                                // called once by the factory at time of deployment
                                function initialize(address _token0, address _token1) external {
                                    require(msg.sender == factory, 'UniswapV2: FORBIDDEN'); // sufficient check
                                    token0 = _token0;
                                    token1 = _token1;
                                }
                            
                                // update reserves and, on the first call per block, price accumulators
                                function _update(uint balance0, uint balance1, uint112 _reserve0, uint112 _reserve1) private {
                                    require(balance0 <= uint112(-1) && balance1 <= uint112(-1), 'UniswapV2: OVERFLOW');
                                    uint32 blockTimestamp = uint32(block.timestamp % 2**32);
                                    uint32 timeElapsed = blockTimestamp - blockTimestampLast; // overflow is desired
                                    if (timeElapsed > 0 && _reserve0 != 0 && _reserve1 != 0) {
                                        // * never overflows, and + overflow is desired
                                        price0CumulativeLast += uint(UQ112x112.encode(_reserve1).uqdiv(_reserve0)) * timeElapsed;
                                        price1CumulativeLast += uint(UQ112x112.encode(_reserve0).uqdiv(_reserve1)) * timeElapsed;
                                    }
                                    reserve0 = uint112(balance0);
                                    reserve1 = uint112(balance1);
                                    blockTimestampLast = blockTimestamp;
                                    emit Sync(reserve0, reserve1);
                                }
                            
                                // if fee is on, mint liquidity equivalent to 1/6th of the growth in sqrt(k)
                                function _mintFee(uint112 _reserve0, uint112 _reserve1) private returns (bool feeOn) {
                                    address feeTo = IUniswapV2Factory(factory).feeTo();
                                    feeOn = feeTo != address(0);
                                    uint _kLast = kLast; // gas savings
                                    if (feeOn) {
                                        if (_kLast != 0) {
                                            uint rootK = Math.sqrt(uint(_reserve0).mul(_reserve1));
                                            uint rootKLast = Math.sqrt(_kLast);
                                            if (rootK > rootKLast) {
                                                uint numerator = totalSupply.mul(rootK.sub(rootKLast));
                                                uint denominator = rootK.mul(5).add(rootKLast);
                                                uint liquidity = numerator / denominator;
                                                if (liquidity > 0) _mint(feeTo, liquidity);
                                            }
                                        }
                                    } else if (_kLast != 0) {
                                        kLast = 0;
                                    }
                                }
                            
                                // this low-level function should be called from a contract which performs important safety checks
                                function mint(address to) external lock returns (uint liquidity) {
                                    (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
                                    uint balance0 = IERC20(token0).balanceOf(address(this));
                                    uint balance1 = IERC20(token1).balanceOf(address(this));
                                    uint amount0 = balance0.sub(_reserve0);
                                    uint amount1 = balance1.sub(_reserve1);
                            
                                    bool feeOn = _mintFee(_reserve0, _reserve1);
                                    uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
                                    if (_totalSupply == 0) {
                                        liquidity = Math.sqrt(amount0.mul(amount1)).sub(MINIMUM_LIQUIDITY);
                                       _mint(address(0), MINIMUM_LIQUIDITY); // permanently lock the first MINIMUM_LIQUIDITY tokens
                                    } else {
                                        liquidity = Math.min(amount0.mul(_totalSupply) / _reserve0, amount1.mul(_totalSupply) / _reserve1);
                                    }
                                    require(liquidity > 0, 'UniswapV2: INSUFFICIENT_LIQUIDITY_MINTED');
                                    _mint(to, liquidity);
                            
                                    _update(balance0, balance1, _reserve0, _reserve1);
                                    if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 and reserve1 are up-to-date
                                    emit Mint(msg.sender, amount0, amount1);
                                }
                            
                                // this low-level function should be called from a contract which performs important safety checks
                                function burn(address to) external lock returns (uint amount0, uint amount1) {
                                    (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
                                    address _token0 = token0;                                // gas savings
                                    address _token1 = token1;                                // gas savings
                                    uint balance0 = IERC20(_token0).balanceOf(address(this));
                                    uint balance1 = IERC20(_token1).balanceOf(address(this));
                                    uint liquidity = balanceOf[address(this)];
                            
                                    bool feeOn = _mintFee(_reserve0, _reserve1);
                                    uint _totalSupply = totalSupply; // gas savings, must be defined here since totalSupply can update in _mintFee
                                    amount0 = liquidity.mul(balance0) / _totalSupply; // using balances ensures pro-rata distribution
                                    amount1 = liquidity.mul(balance1) / _totalSupply; // using balances ensures pro-rata distribution
                                    require(amount0 > 0 && amount1 > 0, 'UniswapV2: INSUFFICIENT_LIQUIDITY_BURNED');
                                    _burn(address(this), liquidity);
                                    _safeTransfer(_token0, to, amount0);
                                    _safeTransfer(_token1, to, amount1);
                                    balance0 = IERC20(_token0).balanceOf(address(this));
                                    balance1 = IERC20(_token1).balanceOf(address(this));
                            
                                    _update(balance0, balance1, _reserve0, _reserve1);
                                    if (feeOn) kLast = uint(reserve0).mul(reserve1); // reserve0 and reserve1 are up-to-date
                                    emit Burn(msg.sender, amount0, amount1, to);
                                }
                            
                                // this low-level function should be called from a contract which performs important safety checks
                                function swap(uint amount0Out, uint amount1Out, address to, bytes calldata data) external lock {
                                    require(amount0Out > 0 || amount1Out > 0, 'UniswapV2: INSUFFICIENT_OUTPUT_AMOUNT');
                                    (uint112 _reserve0, uint112 _reserve1,) = getReserves(); // gas savings
                                    require(amount0Out < _reserve0 && amount1Out < _reserve1, 'UniswapV2: INSUFFICIENT_LIQUIDITY');
                            
                                    uint balance0;
                                    uint balance1;
                                    { // scope for _token{0,1}, avoids stack too deep errors
                                    address _token0 = token0;
                                    address _token1 = token1;
                                    require(to != _token0 && to != _token1, 'UniswapV2: INVALID_TO');
                                    if (amount0Out > 0) _safeTransfer(_token0, to, amount0Out); // optimistically transfer tokens
                                    if (amount1Out > 0) _safeTransfer(_token1, to, amount1Out); // optimistically transfer tokens
                                    if (data.length > 0) IUniswapV2Callee(to).uniswapV2Call(msg.sender, amount0Out, amount1Out, data);
                                    balance0 = IERC20(_token0).balanceOf(address(this));
                                    balance1 = IERC20(_token1).balanceOf(address(this));
                                    }
                                    uint amount0In = balance0 > _reserve0 - amount0Out ? balance0 - (_reserve0 - amount0Out) : 0;
                                    uint amount1In = balance1 > _reserve1 - amount1Out ? balance1 - (_reserve1 - amount1Out) : 0;
                                    require(amount0In > 0 || amount1In > 0, 'UniswapV2: INSUFFICIENT_INPUT_AMOUNT');
                                    { // scope for reserve{0,1}Adjusted, avoids stack too deep errors
                                    uint balance0Adjusted = balance0.mul(1000).sub(amount0In.mul(3));
                                    uint balance1Adjusted = balance1.mul(1000).sub(amount1In.mul(3));
                                    require(balance0Adjusted.mul(balance1Adjusted) >= uint(_reserve0).mul(_reserve1).mul(1000**2), 'UniswapV2: K');
                                    }
                            
                                    _update(balance0, balance1, _reserve0, _reserve1);
                                    emit Swap(msg.sender, amount0In, amount1In, amount0Out, amount1Out, to);
                                }
                            
                                // force balances to match reserves
                                function skim(address to) external lock {
                                    address _token0 = token0; // gas savings
                                    address _token1 = token1; // gas savings
                                    _safeTransfer(_token0, to, IERC20(_token0).balanceOf(address(this)).sub(reserve0));
                                    _safeTransfer(_token1, to, IERC20(_token1).balanceOf(address(this)).sub(reserve1));
                                }
                            
                                // force reserves to match balances
                                function sync() external lock {
                                    _update(IERC20(token0).balanceOf(address(this)), IERC20(token1).balanceOf(address(this)), reserve0, reserve1);
                                }
                            }