ETH Price: $2,619.16 (+4.03%)

Transaction Decoder

Block:
22705274 at Jun-14-2025 08:46:47 PM +UTC
Transaction Fee:
0.0001353644520954 ETH $0.35
Gas Used:
140,470 Gas / 0.96365382 Gwei

Emitted Events:

264 GhoToken.Transfer( from=UniswapV3Pool, to=[Sender] 0xfda1215797d29414e588b2e62fc390ee2949aaaa, value=60034645384647065444 )
265 FiatTokenProxy.0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef( 0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef, 0x000000000000000000000000fda1215797d29414e588b2e62fc390ee2949aaaa, 0x0000000000000000000000005c95d4b1c3321cf898d25949f41d50be2db5bc1d, 0000000000000000000000000000000000000000000000000000000003938700 )
266 UniswapV3Pool.Swap( sender=[Receiver] ZeroEx, recipient=[Sender] 0xfda1215797d29414e588b2e62fc390ee2949aaaa, amount0=-60034645384647065444, amount1=60000000, sqrtPriceX96=79185497320367055393910, liquidity=851512425431583983956, tick=-276335 )

Account State Difference:

  Address   Before After State Difference Code
0x40D16FC0...D28aE6C2f
(Titan Builder)
10.010444694094241244 Eth10.010514929094241244 Eth0.000070235
0x5c95d4B1...e2dB5bc1d
(Uniswap V3: GHO-USDC 3)
0xA0b86991...E3606eB48
0xFda12157...e2949aaAA
1.291626293727244291 Eth
Nonce: 5664
1.291490929275148891 Eth
Nonce: 5665
0.0001353644520954

Execution Trace

ZeroEx.6af479b2( )
  • UniswapV3Feature.sellTokenForTokenToUniswapV3( encodedPath=0xA0B86991C6218B36C1D19D4A2E9EB0CE3606EB480001F440D16FC0246AD3160CCC09B8D0D3A2CD28AE6C2F, sellAmount=60000000, minBuyAmount=59434298930800307178, recipient=0x0000000000000000000000000000000000000000 ) => ( buyAmount=60034645384647065444 )
    • UniswapV3Pool.swap( recipient=0xFda1215797D29414E588B2e62fC390Ee2949aaAA, zeroForOne=False, amountSpecified=60000000, sqrtPriceLimitX96=1461446703485210103287273052203988822378723970341, data=0x000000000000000000000000A0B86991C6218B36C1D19D4A2E9EB0CE3606EB4800000000000000000000000040D16FC0246AD3160CCC09B8D0D3A2CD28AE6C2F00000000000000000000000000000000000000000000000000000000000001F4000000000000000000000000FDA1215797D29414E588B2E62FC390EE2949AAAA ) => ( amount0=-60034645384647065444, amount1=60000000 )
      • GhoToken.transfer( to=0xFda1215797D29414E588B2e62fC390Ee2949aaAA, amount=60034645384647065444 ) => ( True )
      • FiatTokenProxy.70a08231( )
        • FiatTokenV2_2.balanceOf( account=0x5c95d4B1C3321CF898D25949F41D50Be2dB5bc1d ) => ( 259169128250 )
        • ZeroEx.fa461e33( )
          • UniswapV3Feature.uniswapV3SwapCallback( amount0Delta=-60034645384647065444, amount1Delta=60000000, data=0x000000000000000000000000A0B86991C6218B36C1D19D4A2E9EB0CE3606EB4800000000000000000000000040D16FC0246AD3160CCC09B8D0D3A2CD28AE6C2F00000000000000000000000000000000000000000000000000000000000001F4000000000000000000000000FDA1215797D29414E588B2E62FC390EE2949AAAA )
            • FiatTokenProxy.23b872dd( )
              • FiatTokenV2_2.transferFrom( from=0xFda1215797D29414E588B2e62fC390Ee2949aaAA, to=0x5c95d4B1C3321CF898D25949F41D50Be2dB5bc1d, value=60000000 ) => ( True )
              • FiatTokenProxy.70a08231( )
                • FiatTokenV2_2.balanceOf( account=0x5c95d4B1C3321CF898D25949F41D50Be2dB5bc1d ) => ( 259229128250 )
                  File 1 of 6: 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 6: UniswapV3Pool
                  // SPDX-License-Identifier: BUSL-1.1
                  pragma solidity =0.7.6;
                  import './interfaces/IUniswapV3Pool.sol';
                  import './NoDelegateCall.sol';
                  import './libraries/LowGasSafeMath.sol';
                  import './libraries/SafeCast.sol';
                  import './libraries/Tick.sol';
                  import './libraries/TickBitmap.sol';
                  import './libraries/Position.sol';
                  import './libraries/Oracle.sol';
                  import './libraries/FullMath.sol';
                  import './libraries/FixedPoint128.sol';
                  import './libraries/TransferHelper.sol';
                  import './libraries/TickMath.sol';
                  import './libraries/LiquidityMath.sol';
                  import './libraries/SqrtPriceMath.sol';
                  import './libraries/SwapMath.sol';
                  import './interfaces/IUniswapV3PoolDeployer.sol';
                  import './interfaces/IUniswapV3Factory.sol';
                  import './interfaces/IERC20Minimal.sol';
                  import './interfaces/callback/IUniswapV3MintCallback.sol';
                  import './interfaces/callback/IUniswapV3SwapCallback.sol';
                  import './interfaces/callback/IUniswapV3FlashCallback.sol';
                  contract UniswapV3Pool is IUniswapV3Pool, NoDelegateCall {
                      using LowGasSafeMath for uint256;
                      using LowGasSafeMath for int256;
                      using SafeCast for uint256;
                      using SafeCast for int256;
                      using Tick for mapping(int24 => Tick.Info);
                      using TickBitmap for mapping(int16 => uint256);
                      using Position for mapping(bytes32 => Position.Info);
                      using Position for Position.Info;
                      using Oracle for Oracle.Observation[65535];
                      /// @inheritdoc IUniswapV3PoolImmutables
                      address public immutable override factory;
                      /// @inheritdoc IUniswapV3PoolImmutables
                      address public immutable override token0;
                      /// @inheritdoc IUniswapV3PoolImmutables
                      address public immutable override token1;
                      /// @inheritdoc IUniswapV3PoolImmutables
                      uint24 public immutable override fee;
                      /// @inheritdoc IUniswapV3PoolImmutables
                      int24 public immutable override tickSpacing;
                      /// @inheritdoc IUniswapV3PoolImmutables
                      uint128 public immutable override maxLiquidityPerTick;
                      struct Slot0 {
                          // the current price
                          uint160 sqrtPriceX96;
                          // the current tick
                          int24 tick;
                          // the most-recently updated index of the observations array
                          uint16 observationIndex;
                          // the current maximum number of observations that are being stored
                          uint16 observationCardinality;
                          // the next maximum number of observations to store, triggered in observations.write
                          uint16 observationCardinalityNext;
                          // the current protocol fee as a percentage of the swap fee taken on withdrawal
                          // represented as an integer denominator (1/x)%
                          uint8 feeProtocol;
                          // whether the pool is locked
                          bool unlocked;
                      }
                      /// @inheritdoc IUniswapV3PoolState
                      Slot0 public override slot0;
                      /// @inheritdoc IUniswapV3PoolState
                      uint256 public override feeGrowthGlobal0X128;
                      /// @inheritdoc IUniswapV3PoolState
                      uint256 public override feeGrowthGlobal1X128;
                      // accumulated protocol fees in token0/token1 units
                      struct ProtocolFees {
                          uint128 token0;
                          uint128 token1;
                      }
                      /// @inheritdoc IUniswapV3PoolState
                      ProtocolFees public override protocolFees;
                      /// @inheritdoc IUniswapV3PoolState
                      uint128 public override liquidity;
                      /// @inheritdoc IUniswapV3PoolState
                      mapping(int24 => Tick.Info) public override ticks;
                      /// @inheritdoc IUniswapV3PoolState
                      mapping(int16 => uint256) public override tickBitmap;
                      /// @inheritdoc IUniswapV3PoolState
                      mapping(bytes32 => Position.Info) public override positions;
                      /// @inheritdoc IUniswapV3PoolState
                      Oracle.Observation[65535] public override observations;
                      /// @dev Mutually exclusive reentrancy protection into the pool to/from a method. This method also prevents entrance
                      /// to a function before the pool is initialized. The reentrancy guard is required throughout the contract because
                      /// we use balance checks to determine the payment status of interactions such as mint, swap and flash.
                      modifier lock() {
                          require(slot0.unlocked, 'LOK');
                          slot0.unlocked = false;
                          _;
                          slot0.unlocked = true;
                      }
                      /// @dev Prevents calling a function from anyone except the address returned by IUniswapV3Factory#owner()
                      modifier onlyFactoryOwner() {
                          require(msg.sender == IUniswapV3Factory(factory).owner());
                          _;
                      }
                      constructor() {
                          int24 _tickSpacing;
                          (factory, token0, token1, fee, _tickSpacing) = IUniswapV3PoolDeployer(msg.sender).parameters();
                          tickSpacing = _tickSpacing;
                          maxLiquidityPerTick = Tick.tickSpacingToMaxLiquidityPerTick(_tickSpacing);
                      }
                      /// @dev Common checks for valid tick inputs.
                      function checkTicks(int24 tickLower, int24 tickUpper) private pure {
                          require(tickLower < tickUpper, 'TLU');
                          require(tickLower >= TickMath.MIN_TICK, 'TLM');
                          require(tickUpper <= TickMath.MAX_TICK, 'TUM');
                      }
                      /// @dev Returns the block timestamp truncated to 32 bits, i.e. mod 2**32. This method is overridden in tests.
                      function _blockTimestamp() internal view virtual returns (uint32) {
                          return uint32(block.timestamp); // truncation is desired
                      }
                      /// @dev Get the pool's balance of token0
                      /// @dev This function is gas optimized to avoid a redundant extcodesize check in addition to the returndatasize
                      /// check
                      function balance0() private view returns (uint256) {
                          (bool success, bytes memory data) =
                              token0.staticcall(abi.encodeWithSelector(IERC20Minimal.balanceOf.selector, address(this)));
                          require(success && data.length >= 32);
                          return abi.decode(data, (uint256));
                      }
                      /// @dev Get the pool's balance of token1
                      /// @dev This function is gas optimized to avoid a redundant extcodesize check in addition to the returndatasize
                      /// check
                      function balance1() private view returns (uint256) {
                          (bool success, bytes memory data) =
                              token1.staticcall(abi.encodeWithSelector(IERC20Minimal.balanceOf.selector, address(this)));
                          require(success && data.length >= 32);
                          return abi.decode(data, (uint256));
                      }
                      /// @inheritdoc IUniswapV3PoolDerivedState
                      function snapshotCumulativesInside(int24 tickLower, int24 tickUpper)
                          external
                          view
                          override
                          noDelegateCall
                          returns (
                              int56 tickCumulativeInside,
                              uint160 secondsPerLiquidityInsideX128,
                              uint32 secondsInside
                          )
                      {
                          checkTicks(tickLower, tickUpper);
                          int56 tickCumulativeLower;
                          int56 tickCumulativeUpper;
                          uint160 secondsPerLiquidityOutsideLowerX128;
                          uint160 secondsPerLiquidityOutsideUpperX128;
                          uint32 secondsOutsideLower;
                          uint32 secondsOutsideUpper;
                          {
                              Tick.Info storage lower = ticks[tickLower];
                              Tick.Info storage upper = ticks[tickUpper];
                              bool initializedLower;
                              (tickCumulativeLower, secondsPerLiquidityOutsideLowerX128, secondsOutsideLower, initializedLower) = (
                                  lower.tickCumulativeOutside,
                                  lower.secondsPerLiquidityOutsideX128,
                                  lower.secondsOutside,
                                  lower.initialized
                              );
                              require(initializedLower);
                              bool initializedUpper;
                              (tickCumulativeUpper, secondsPerLiquidityOutsideUpperX128, secondsOutsideUpper, initializedUpper) = (
                                  upper.tickCumulativeOutside,
                                  upper.secondsPerLiquidityOutsideX128,
                                  upper.secondsOutside,
                                  upper.initialized
                              );
                              require(initializedUpper);
                          }
                          Slot0 memory _slot0 = slot0;
                          if (_slot0.tick < tickLower) {
                              return (
                                  tickCumulativeLower - tickCumulativeUpper,
                                  secondsPerLiquidityOutsideLowerX128 - secondsPerLiquidityOutsideUpperX128,
                                  secondsOutsideLower - secondsOutsideUpper
                              );
                          } else if (_slot0.tick < tickUpper) {
                              uint32 time = _blockTimestamp();
                              (int56 tickCumulative, uint160 secondsPerLiquidityCumulativeX128) =
                                  observations.observeSingle(
                                      time,
                                      0,
                                      _slot0.tick,
                                      _slot0.observationIndex,
                                      liquidity,
                                      _slot0.observationCardinality
                                  );
                              return (
                                  tickCumulative - tickCumulativeLower - tickCumulativeUpper,
                                  secondsPerLiquidityCumulativeX128 -
                                      secondsPerLiquidityOutsideLowerX128 -
                                      secondsPerLiquidityOutsideUpperX128,
                                  time - secondsOutsideLower - secondsOutsideUpper
                              );
                          } else {
                              return (
                                  tickCumulativeUpper - tickCumulativeLower,
                                  secondsPerLiquidityOutsideUpperX128 - secondsPerLiquidityOutsideLowerX128,
                                  secondsOutsideUpper - secondsOutsideLower
                              );
                          }
                      }
                      /// @inheritdoc IUniswapV3PoolDerivedState
                      function observe(uint32[] calldata secondsAgos)
                          external
                          view
                          override
                          noDelegateCall
                          returns (int56[] memory tickCumulatives, uint160[] memory secondsPerLiquidityCumulativeX128s)
                      {
                          return
                              observations.observe(
                                  _blockTimestamp(),
                                  secondsAgos,
                                  slot0.tick,
                                  slot0.observationIndex,
                                  liquidity,
                                  slot0.observationCardinality
                              );
                      }
                      /// @inheritdoc IUniswapV3PoolActions
                      function increaseObservationCardinalityNext(uint16 observationCardinalityNext)
                          external
                          override
                          lock
                          noDelegateCall
                      {
                          uint16 observationCardinalityNextOld = slot0.observationCardinalityNext; // for the event
                          uint16 observationCardinalityNextNew =
                              observations.grow(observationCardinalityNextOld, observationCardinalityNext);
                          slot0.observationCardinalityNext = observationCardinalityNextNew;
                          if (observationCardinalityNextOld != observationCardinalityNextNew)
                              emit IncreaseObservationCardinalityNext(observationCardinalityNextOld, observationCardinalityNextNew);
                      }
                      /// @inheritdoc IUniswapV3PoolActions
                      /// @dev not locked because it initializes unlocked
                      function initialize(uint160 sqrtPriceX96) external override {
                          require(slot0.sqrtPriceX96 == 0, 'AI');
                          int24 tick = TickMath.getTickAtSqrtRatio(sqrtPriceX96);
                          (uint16 cardinality, uint16 cardinalityNext) = observations.initialize(_blockTimestamp());
                          slot0 = Slot0({
                              sqrtPriceX96: sqrtPriceX96,
                              tick: tick,
                              observationIndex: 0,
                              observationCardinality: cardinality,
                              observationCardinalityNext: cardinalityNext,
                              feeProtocol: 0,
                              unlocked: true
                          });
                          emit Initialize(sqrtPriceX96, tick);
                      }
                      struct ModifyPositionParams {
                          // the address that owns the position
                          address owner;
                          // the lower and upper tick of the position
                          int24 tickLower;
                          int24 tickUpper;
                          // any change in liquidity
                          int128 liquidityDelta;
                      }
                      /// @dev Effect some changes to a position
                      /// @param params the position details and the change to the position's liquidity to effect
                      /// @return position a storage pointer referencing the position with the given owner and tick range
                      /// @return amount0 the amount of token0 owed to the pool, negative if the pool should pay the recipient
                      /// @return amount1 the amount of token1 owed to the pool, negative if the pool should pay the recipient
                      function _modifyPosition(ModifyPositionParams memory params)
                          private
                          noDelegateCall
                          returns (
                              Position.Info storage position,
                              int256 amount0,
                              int256 amount1
                          )
                      {
                          checkTicks(params.tickLower, params.tickUpper);
                          Slot0 memory _slot0 = slot0; // SLOAD for gas optimization
                          position = _updatePosition(
                              params.owner,
                              params.tickLower,
                              params.tickUpper,
                              params.liquidityDelta,
                              _slot0.tick
                          );
                          if (params.liquidityDelta != 0) {
                              if (_slot0.tick < params.tickLower) {
                                  // current tick is below the passed range; liquidity can only become in range by crossing from left to
                                  // right, when we'll need _more_ token0 (it's becoming more valuable) so user must provide it
                                  amount0 = SqrtPriceMath.getAmount0Delta(
                                      TickMath.getSqrtRatioAtTick(params.tickLower),
                                      TickMath.getSqrtRatioAtTick(params.tickUpper),
                                      params.liquidityDelta
                                  );
                              } else if (_slot0.tick < params.tickUpper) {
                                  // current tick is inside the passed range
                                  uint128 liquidityBefore = liquidity; // SLOAD for gas optimization
                                  // write an oracle entry
                                  (slot0.observationIndex, slot0.observationCardinality) = observations.write(
                                      _slot0.observationIndex,
                                      _blockTimestamp(),
                                      _slot0.tick,
                                      liquidityBefore,
                                      _slot0.observationCardinality,
                                      _slot0.observationCardinalityNext
                                  );
                                  amount0 = SqrtPriceMath.getAmount0Delta(
                                      _slot0.sqrtPriceX96,
                                      TickMath.getSqrtRatioAtTick(params.tickUpper),
                                      params.liquidityDelta
                                  );
                                  amount1 = SqrtPriceMath.getAmount1Delta(
                                      TickMath.getSqrtRatioAtTick(params.tickLower),
                                      _slot0.sqrtPriceX96,
                                      params.liquidityDelta
                                  );
                                  liquidity = LiquidityMath.addDelta(liquidityBefore, params.liquidityDelta);
                              } else {
                                  // current tick is above the passed range; liquidity can only become in range by crossing from right to
                                  // left, when we'll need _more_ token1 (it's becoming more valuable) so user must provide it
                                  amount1 = SqrtPriceMath.getAmount1Delta(
                                      TickMath.getSqrtRatioAtTick(params.tickLower),
                                      TickMath.getSqrtRatioAtTick(params.tickUpper),
                                      params.liquidityDelta
                                  );
                              }
                          }
                      }
                      /// @dev Gets and updates a position with the given liquidity delta
                      /// @param owner the owner of the position
                      /// @param tickLower the lower tick of the position's tick range
                      /// @param tickUpper the upper tick of the position's tick range
                      /// @param tick the current tick, passed to avoid sloads
                      function _updatePosition(
                          address owner,
                          int24 tickLower,
                          int24 tickUpper,
                          int128 liquidityDelta,
                          int24 tick
                      ) private returns (Position.Info storage position) {
                          position = positions.get(owner, tickLower, tickUpper);
                          uint256 _feeGrowthGlobal0X128 = feeGrowthGlobal0X128; // SLOAD for gas optimization
                          uint256 _feeGrowthGlobal1X128 = feeGrowthGlobal1X128; // SLOAD for gas optimization
                          // if we need to update the ticks, do it
                          bool flippedLower;
                          bool flippedUpper;
                          if (liquidityDelta != 0) {
                              uint32 time = _blockTimestamp();
                              (int56 tickCumulative, uint160 secondsPerLiquidityCumulativeX128) =
                                  observations.observeSingle(
                                      time,
                                      0,
                                      slot0.tick,
                                      slot0.observationIndex,
                                      liquidity,
                                      slot0.observationCardinality
                                  );
                              flippedLower = ticks.update(
                                  tickLower,
                                  tick,
                                  liquidityDelta,
                                  _feeGrowthGlobal0X128,
                                  _feeGrowthGlobal1X128,
                                  secondsPerLiquidityCumulativeX128,
                                  tickCumulative,
                                  time,
                                  false,
                                  maxLiquidityPerTick
                              );
                              flippedUpper = ticks.update(
                                  tickUpper,
                                  tick,
                                  liquidityDelta,
                                  _feeGrowthGlobal0X128,
                                  _feeGrowthGlobal1X128,
                                  secondsPerLiquidityCumulativeX128,
                                  tickCumulative,
                                  time,
                                  true,
                                  maxLiquidityPerTick
                              );
                              if (flippedLower) {
                                  tickBitmap.flipTick(tickLower, tickSpacing);
                              }
                              if (flippedUpper) {
                                  tickBitmap.flipTick(tickUpper, tickSpacing);
                              }
                          }
                          (uint256 feeGrowthInside0X128, uint256 feeGrowthInside1X128) =
                              ticks.getFeeGrowthInside(tickLower, tickUpper, tick, _feeGrowthGlobal0X128, _feeGrowthGlobal1X128);
                          position.update(liquidityDelta, feeGrowthInside0X128, feeGrowthInside1X128);
                          // clear any tick data that is no longer needed
                          if (liquidityDelta < 0) {
                              if (flippedLower) {
                                  ticks.clear(tickLower);
                              }
                              if (flippedUpper) {
                                  ticks.clear(tickUpper);
                              }
                          }
                      }
                      /// @inheritdoc IUniswapV3PoolActions
                      /// @dev noDelegateCall is applied indirectly via _modifyPosition
                      function mint(
                          address recipient,
                          int24 tickLower,
                          int24 tickUpper,
                          uint128 amount,
                          bytes calldata data
                      ) external override lock returns (uint256 amount0, uint256 amount1) {
                          require(amount > 0);
                          (, int256 amount0Int, int256 amount1Int) =
                              _modifyPosition(
                                  ModifyPositionParams({
                                      owner: recipient,
                                      tickLower: tickLower,
                                      tickUpper: tickUpper,
                                      liquidityDelta: int256(amount).toInt128()
                                  })
                              );
                          amount0 = uint256(amount0Int);
                          amount1 = uint256(amount1Int);
                          uint256 balance0Before;
                          uint256 balance1Before;
                          if (amount0 > 0) balance0Before = balance0();
                          if (amount1 > 0) balance1Before = balance1();
                          IUniswapV3MintCallback(msg.sender).uniswapV3MintCallback(amount0, amount1, data);
                          if (amount0 > 0) require(balance0Before.add(amount0) <= balance0(), 'M0');
                          if (amount1 > 0) require(balance1Before.add(amount1) <= balance1(), 'M1');
                          emit Mint(msg.sender, recipient, tickLower, tickUpper, amount, amount0, amount1);
                      }
                      /// @inheritdoc IUniswapV3PoolActions
                      function collect(
                          address recipient,
                          int24 tickLower,
                          int24 tickUpper,
                          uint128 amount0Requested,
                          uint128 amount1Requested
                      ) external override lock returns (uint128 amount0, uint128 amount1) {
                          // we don't need to checkTicks here, because invalid positions will never have non-zero tokensOwed{0,1}
                          Position.Info storage position = positions.get(msg.sender, tickLower, tickUpper);
                          amount0 = amount0Requested > position.tokensOwed0 ? position.tokensOwed0 : amount0Requested;
                          amount1 = amount1Requested > position.tokensOwed1 ? position.tokensOwed1 : amount1Requested;
                          if (amount0 > 0) {
                              position.tokensOwed0 -= amount0;
                              TransferHelper.safeTransfer(token0, recipient, amount0);
                          }
                          if (amount1 > 0) {
                              position.tokensOwed1 -= amount1;
                              TransferHelper.safeTransfer(token1, recipient, amount1);
                          }
                          emit Collect(msg.sender, recipient, tickLower, tickUpper, amount0, amount1);
                      }
                      /// @inheritdoc IUniswapV3PoolActions
                      /// @dev noDelegateCall is applied indirectly via _modifyPosition
                      function burn(
                          int24 tickLower,
                          int24 tickUpper,
                          uint128 amount
                      ) external override lock returns (uint256 amount0, uint256 amount1) {
                          (Position.Info storage position, int256 amount0Int, int256 amount1Int) =
                              _modifyPosition(
                                  ModifyPositionParams({
                                      owner: msg.sender,
                                      tickLower: tickLower,
                                      tickUpper: tickUpper,
                                      liquidityDelta: -int256(amount).toInt128()
                                  })
                              );
                          amount0 = uint256(-amount0Int);
                          amount1 = uint256(-amount1Int);
                          if (amount0 > 0 || amount1 > 0) {
                              (position.tokensOwed0, position.tokensOwed1) = (
                                  position.tokensOwed0 + uint128(amount0),
                                  position.tokensOwed1 + uint128(amount1)
                              );
                          }
                          emit Burn(msg.sender, tickLower, tickUpper, amount, amount0, amount1);
                      }
                      struct SwapCache {
                          // the protocol fee for the input token
                          uint8 feeProtocol;
                          // liquidity at the beginning of the swap
                          uint128 liquidityStart;
                          // the timestamp of the current block
                          uint32 blockTimestamp;
                          // the current value of the tick accumulator, computed only if we cross an initialized tick
                          int56 tickCumulative;
                          // the current value of seconds per liquidity accumulator, computed only if we cross an initialized tick
                          uint160 secondsPerLiquidityCumulativeX128;
                          // whether we've computed and cached the above two accumulators
                          bool computedLatestObservation;
                      }
                      // the top level state of the swap, the results of which are recorded in storage at the end
                      struct SwapState {
                          // the amount remaining to be swapped in/out of the input/output asset
                          int256 amountSpecifiedRemaining;
                          // the amount already swapped out/in of the output/input asset
                          int256 amountCalculated;
                          // current sqrt(price)
                          uint160 sqrtPriceX96;
                          // the tick associated with the current price
                          int24 tick;
                          // the global fee growth of the input token
                          uint256 feeGrowthGlobalX128;
                          // amount of input token paid as protocol fee
                          uint128 protocolFee;
                          // the current liquidity in range
                          uint128 liquidity;
                      }
                      struct StepComputations {
                          // the price at the beginning of the step
                          uint160 sqrtPriceStartX96;
                          // the next tick to swap to from the current tick in the swap direction
                          int24 tickNext;
                          // whether tickNext is initialized or not
                          bool initialized;
                          // sqrt(price) for the next tick (1/0)
                          uint160 sqrtPriceNextX96;
                          // how much is being swapped in in this step
                          uint256 amountIn;
                          // how much is being swapped out
                          uint256 amountOut;
                          // how much fee is being paid in
                          uint256 feeAmount;
                      }
                      /// @inheritdoc IUniswapV3PoolActions
                      function swap(
                          address recipient,
                          bool zeroForOne,
                          int256 amountSpecified,
                          uint160 sqrtPriceLimitX96,
                          bytes calldata data
                      ) external override noDelegateCall returns (int256 amount0, int256 amount1) {
                          require(amountSpecified != 0, 'AS');
                          Slot0 memory slot0Start = slot0;
                          require(slot0Start.unlocked, 'LOK');
                          require(
                              zeroForOne
                                  ? sqrtPriceLimitX96 < slot0Start.sqrtPriceX96 && sqrtPriceLimitX96 > TickMath.MIN_SQRT_RATIO
                                  : sqrtPriceLimitX96 > slot0Start.sqrtPriceX96 && sqrtPriceLimitX96 < TickMath.MAX_SQRT_RATIO,
                              'SPL'
                          );
                          slot0.unlocked = false;
                          SwapCache memory cache =
                              SwapCache({
                                  liquidityStart: liquidity,
                                  blockTimestamp: _blockTimestamp(),
                                  feeProtocol: zeroForOne ? (slot0Start.feeProtocol % 16) : (slot0Start.feeProtocol >> 4),
                                  secondsPerLiquidityCumulativeX128: 0,
                                  tickCumulative: 0,
                                  computedLatestObservation: false
                              });
                          bool exactInput = amountSpecified > 0;
                          SwapState memory state =
                              SwapState({
                                  amountSpecifiedRemaining: amountSpecified,
                                  amountCalculated: 0,
                                  sqrtPriceX96: slot0Start.sqrtPriceX96,
                                  tick: slot0Start.tick,
                                  feeGrowthGlobalX128: zeroForOne ? feeGrowthGlobal0X128 : feeGrowthGlobal1X128,
                                  protocolFee: 0,
                                  liquidity: cache.liquidityStart
                              });
                          // continue swapping as long as we haven't used the entire input/output and haven't reached the price limit
                          while (state.amountSpecifiedRemaining != 0 && state.sqrtPriceX96 != sqrtPriceLimitX96) {
                              StepComputations memory step;
                              step.sqrtPriceStartX96 = state.sqrtPriceX96;
                              (step.tickNext, step.initialized) = tickBitmap.nextInitializedTickWithinOneWord(
                                  state.tick,
                                  tickSpacing,
                                  zeroForOne
                              );
                              // ensure that we do not overshoot the min/max tick, as the tick bitmap is not aware of these bounds
                              if (step.tickNext < TickMath.MIN_TICK) {
                                  step.tickNext = TickMath.MIN_TICK;
                              } else if (step.tickNext > TickMath.MAX_TICK) {
                                  step.tickNext = TickMath.MAX_TICK;
                              }
                              // get the price for the next tick
                              step.sqrtPriceNextX96 = TickMath.getSqrtRatioAtTick(step.tickNext);
                              // compute values to swap to the target tick, price limit, or point where input/output amount is exhausted
                              (state.sqrtPriceX96, step.amountIn, step.amountOut, step.feeAmount) = SwapMath.computeSwapStep(
                                  state.sqrtPriceX96,
                                  (zeroForOne ? step.sqrtPriceNextX96 < sqrtPriceLimitX96 : step.sqrtPriceNextX96 > sqrtPriceLimitX96)
                                      ? sqrtPriceLimitX96
                                      : step.sqrtPriceNextX96,
                                  state.liquidity,
                                  state.amountSpecifiedRemaining,
                                  fee
                              );
                              if (exactInput) {
                                  state.amountSpecifiedRemaining -= (step.amountIn + step.feeAmount).toInt256();
                                  state.amountCalculated = state.amountCalculated.sub(step.amountOut.toInt256());
                              } else {
                                  state.amountSpecifiedRemaining += step.amountOut.toInt256();
                                  state.amountCalculated = state.amountCalculated.add((step.amountIn + step.feeAmount).toInt256());
                              }
                              // if the protocol fee is on, calculate how much is owed, decrement feeAmount, and increment protocolFee
                              if (cache.feeProtocol > 0) {
                                  uint256 delta = step.feeAmount / cache.feeProtocol;
                                  step.feeAmount -= delta;
                                  state.protocolFee += uint128(delta);
                              }
                              // update global fee tracker
                              if (state.liquidity > 0)
                                  state.feeGrowthGlobalX128 += FullMath.mulDiv(step.feeAmount, FixedPoint128.Q128, state.liquidity);
                              // shift tick if we reached the next price
                              if (state.sqrtPriceX96 == step.sqrtPriceNextX96) {
                                  // if the tick is initialized, run the tick transition
                                  if (step.initialized) {
                                      // check for the placeholder value, which we replace with the actual value the first time the swap
                                      // crosses an initialized tick
                                      if (!cache.computedLatestObservation) {
                                          (cache.tickCumulative, cache.secondsPerLiquidityCumulativeX128) = observations.observeSingle(
                                              cache.blockTimestamp,
                                              0,
                                              slot0Start.tick,
                                              slot0Start.observationIndex,
                                              cache.liquidityStart,
                                              slot0Start.observationCardinality
                                          );
                                          cache.computedLatestObservation = true;
                                      }
                                      int128 liquidityNet =
                                          ticks.cross(
                                              step.tickNext,
                                              (zeroForOne ? state.feeGrowthGlobalX128 : feeGrowthGlobal0X128),
                                              (zeroForOne ? feeGrowthGlobal1X128 : state.feeGrowthGlobalX128),
                                              cache.secondsPerLiquidityCumulativeX128,
                                              cache.tickCumulative,
                                              cache.blockTimestamp
                                          );
                                      // if we're moving leftward, we interpret liquidityNet as the opposite sign
                                      // safe because liquidityNet cannot be type(int128).min
                                      if (zeroForOne) liquidityNet = -liquidityNet;
                                      state.liquidity = LiquidityMath.addDelta(state.liquidity, liquidityNet);
                                  }
                                  state.tick = zeroForOne ? step.tickNext - 1 : step.tickNext;
                              } else if (state.sqrtPriceX96 != step.sqrtPriceStartX96) {
                                  // recompute unless we're on a lower tick boundary (i.e. already transitioned ticks), and haven't moved
                                  state.tick = TickMath.getTickAtSqrtRatio(state.sqrtPriceX96);
                              }
                          }
                          // update tick and write an oracle entry if the tick change
                          if (state.tick != slot0Start.tick) {
                              (uint16 observationIndex, uint16 observationCardinality) =
                                  observations.write(
                                      slot0Start.observationIndex,
                                      cache.blockTimestamp,
                                      slot0Start.tick,
                                      cache.liquidityStart,
                                      slot0Start.observationCardinality,
                                      slot0Start.observationCardinalityNext
                                  );
                              (slot0.sqrtPriceX96, slot0.tick, slot0.observationIndex, slot0.observationCardinality) = (
                                  state.sqrtPriceX96,
                                  state.tick,
                                  observationIndex,
                                  observationCardinality
                              );
                          } else {
                              // otherwise just update the price
                              slot0.sqrtPriceX96 = state.sqrtPriceX96;
                          }
                          // update liquidity if it changed
                          if (cache.liquidityStart != state.liquidity) liquidity = state.liquidity;
                          // update fee growth global and, if necessary, protocol fees
                          // overflow is acceptable, protocol has to withdraw before it hits type(uint128).max fees
                          if (zeroForOne) {
                              feeGrowthGlobal0X128 = state.feeGrowthGlobalX128;
                              if (state.protocolFee > 0) protocolFees.token0 += state.protocolFee;
                          } else {
                              feeGrowthGlobal1X128 = state.feeGrowthGlobalX128;
                              if (state.protocolFee > 0) protocolFees.token1 += state.protocolFee;
                          }
                          (amount0, amount1) = zeroForOne == exactInput
                              ? (amountSpecified - state.amountSpecifiedRemaining, state.amountCalculated)
                              : (state.amountCalculated, amountSpecified - state.amountSpecifiedRemaining);
                          // do the transfers and collect payment
                          if (zeroForOne) {
                              if (amount1 < 0) TransferHelper.safeTransfer(token1, recipient, uint256(-amount1));
                              uint256 balance0Before = balance0();
                              IUniswapV3SwapCallback(msg.sender).uniswapV3SwapCallback(amount0, amount1, data);
                              require(balance0Before.add(uint256(amount0)) <= balance0(), 'IIA');
                          } else {
                              if (amount0 < 0) TransferHelper.safeTransfer(token0, recipient, uint256(-amount0));
                              uint256 balance1Before = balance1();
                              IUniswapV3SwapCallback(msg.sender).uniswapV3SwapCallback(amount0, amount1, data);
                              require(balance1Before.add(uint256(amount1)) <= balance1(), 'IIA');
                          }
                          emit Swap(msg.sender, recipient, amount0, amount1, state.sqrtPriceX96, state.liquidity, state.tick);
                          slot0.unlocked = true;
                      }
                      /// @inheritdoc IUniswapV3PoolActions
                      function flash(
                          address recipient,
                          uint256 amount0,
                          uint256 amount1,
                          bytes calldata data
                      ) external override lock noDelegateCall {
                          uint128 _liquidity = liquidity;
                          require(_liquidity > 0, 'L');
                          uint256 fee0 = FullMath.mulDivRoundingUp(amount0, fee, 1e6);
                          uint256 fee1 = FullMath.mulDivRoundingUp(amount1, fee, 1e6);
                          uint256 balance0Before = balance0();
                          uint256 balance1Before = balance1();
                          if (amount0 > 0) TransferHelper.safeTransfer(token0, recipient, amount0);
                          if (amount1 > 0) TransferHelper.safeTransfer(token1, recipient, amount1);
                          IUniswapV3FlashCallback(msg.sender).uniswapV3FlashCallback(fee0, fee1, data);
                          uint256 balance0After = balance0();
                          uint256 balance1After = balance1();
                          require(balance0Before.add(fee0) <= balance0After, 'F0');
                          require(balance1Before.add(fee1) <= balance1After, 'F1');
                          // sub is safe because we know balanceAfter is gt balanceBefore by at least fee
                          uint256 paid0 = balance0After - balance0Before;
                          uint256 paid1 = balance1After - balance1Before;
                          if (paid0 > 0) {
                              uint8 feeProtocol0 = slot0.feeProtocol % 16;
                              uint256 fees0 = feeProtocol0 == 0 ? 0 : paid0 / feeProtocol0;
                              if (uint128(fees0) > 0) protocolFees.token0 += uint128(fees0);
                              feeGrowthGlobal0X128 += FullMath.mulDiv(paid0 - fees0, FixedPoint128.Q128, _liquidity);
                          }
                          if (paid1 > 0) {
                              uint8 feeProtocol1 = slot0.feeProtocol >> 4;
                              uint256 fees1 = feeProtocol1 == 0 ? 0 : paid1 / feeProtocol1;
                              if (uint128(fees1) > 0) protocolFees.token1 += uint128(fees1);
                              feeGrowthGlobal1X128 += FullMath.mulDiv(paid1 - fees1, FixedPoint128.Q128, _liquidity);
                          }
                          emit Flash(msg.sender, recipient, amount0, amount1, paid0, paid1);
                      }
                      /// @inheritdoc IUniswapV3PoolOwnerActions
                      function setFeeProtocol(uint8 feeProtocol0, uint8 feeProtocol1) external override lock onlyFactoryOwner {
                          require(
                              (feeProtocol0 == 0 || (feeProtocol0 >= 4 && feeProtocol0 <= 10)) &&
                                  (feeProtocol1 == 0 || (feeProtocol1 >= 4 && feeProtocol1 <= 10))
                          );
                          uint8 feeProtocolOld = slot0.feeProtocol;
                          slot0.feeProtocol = feeProtocol0 + (feeProtocol1 << 4);
                          emit SetFeeProtocol(feeProtocolOld % 16, feeProtocolOld >> 4, feeProtocol0, feeProtocol1);
                      }
                      /// @inheritdoc IUniswapV3PoolOwnerActions
                      function collectProtocol(
                          address recipient,
                          uint128 amount0Requested,
                          uint128 amount1Requested
                      ) external override lock onlyFactoryOwner returns (uint128 amount0, uint128 amount1) {
                          amount0 = amount0Requested > protocolFees.token0 ? protocolFees.token0 : amount0Requested;
                          amount1 = amount1Requested > protocolFees.token1 ? protocolFees.token1 : amount1Requested;
                          if (amount0 > 0) {
                              if (amount0 == protocolFees.token0) amount0--; // ensure that the slot is not cleared, for gas savings
                              protocolFees.token0 -= amount0;
                              TransferHelper.safeTransfer(token0, recipient, amount0);
                          }
                          if (amount1 > 0) {
                              if (amount1 == protocolFees.token1) amount1--; // ensure that the slot is not cleared, for gas savings
                              protocolFees.token1 -= amount1;
                              TransferHelper.safeTransfer(token1, recipient, amount1);
                          }
                          emit CollectProtocol(msg.sender, recipient, amount0, amount1);
                      }
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.5.0;
                  import './pool/IUniswapV3PoolImmutables.sol';
                  import './pool/IUniswapV3PoolState.sol';
                  import './pool/IUniswapV3PoolDerivedState.sol';
                  import './pool/IUniswapV3PoolActions.sol';
                  import './pool/IUniswapV3PoolOwnerActions.sol';
                  import './pool/IUniswapV3PoolEvents.sol';
                  /// @title The interface for a Uniswap V3 Pool
                  /// @notice A Uniswap pool facilitates swapping and automated market making between any two assets that strictly conform
                  /// to the ERC20 specification
                  /// @dev The pool interface is broken up into many smaller pieces
                  interface IUniswapV3Pool is
                      IUniswapV3PoolImmutables,
                      IUniswapV3PoolState,
                      IUniswapV3PoolDerivedState,
                      IUniswapV3PoolActions,
                      IUniswapV3PoolOwnerActions,
                      IUniswapV3PoolEvents
                  {
                  }
                  // SPDX-License-Identifier: BUSL-1.1
                  pragma solidity =0.7.6;
                  /// @title Prevents delegatecall to a contract
                  /// @notice Base contract that provides a modifier for preventing delegatecall to methods in a child contract
                  abstract contract NoDelegateCall {
                      /// @dev The original address of this contract
                      address private immutable original;
                      constructor() {
                          // Immutables are computed in the init code of the contract, and then inlined into the deployed bytecode.
                          // In other words, this variable won't change when it's checked at runtime.
                          original = address(this);
                      }
                      /// @dev Private method is used instead of inlining into modifier because modifiers are copied into each method,
                      ///     and the use of immutable means the address bytes are copied in every place the modifier is used.
                      function checkNotDelegateCall() private view {
                          require(address(this) == original);
                      }
                      /// @notice Prevents delegatecall into the modified method
                      modifier noDelegateCall() {
                          checkNotDelegateCall();
                          _;
                      }
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.7.0;
                  /// @title Optimized overflow and underflow safe math operations
                  /// @notice Contains methods for doing math operations that revert on overflow or underflow for minimal gas cost
                  library LowGasSafeMath {
                      /// @notice Returns x + y, reverts if sum overflows uint256
                      /// @param x The augend
                      /// @param y The addend
                      /// @return z The sum of x and y
                      function add(uint256 x, uint256 y) internal pure returns (uint256 z) {
                          require((z = x + y) >= x);
                      }
                      /// @notice Returns x - y, reverts if underflows
                      /// @param x The minuend
                      /// @param y The subtrahend
                      /// @return z The difference of x and y
                      function sub(uint256 x, uint256 y) internal pure returns (uint256 z) {
                          require((z = x - y) <= x);
                      }
                      /// @notice Returns x * y, reverts if overflows
                      /// @param x The multiplicand
                      /// @param y The multiplier
                      /// @return z The product of x and y
                      function mul(uint256 x, uint256 y) internal pure returns (uint256 z) {
                          require(x == 0 || (z = x * y) / x == y);
                      }
                      /// @notice Returns x + y, reverts if overflows or underflows
                      /// @param x The augend
                      /// @param y The addend
                      /// @return z The sum of x and y
                      function add(int256 x, int256 y) internal pure returns (int256 z) {
                          require((z = x + y) >= x == (y >= 0));
                      }
                      /// @notice Returns x - y, reverts if overflows or underflows
                      /// @param x The minuend
                      /// @param y The subtrahend
                      /// @return z The difference of x and y
                      function sub(int256 x, int256 y) internal pure returns (int256 z) {
                          require((z = x - y) <= x == (y >= 0));
                      }
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.5.0;
                  /// @title Safe casting methods
                  /// @notice Contains methods for safely casting between types
                  library SafeCast {
                      /// @notice Cast a uint256 to a uint160, revert on overflow
                      /// @param y The uint256 to be downcasted
                      /// @return z The downcasted integer, now type uint160
                      function toUint160(uint256 y) internal pure returns (uint160 z) {
                          require((z = uint160(y)) == y);
                      }
                      /// @notice Cast a int256 to a int128, revert on overflow or underflow
                      /// @param y The int256 to be downcasted
                      /// @return z The downcasted integer, now type int128
                      function toInt128(int256 y) internal pure returns (int128 z) {
                          require((z = int128(y)) == y);
                      }
                      /// @notice Cast a uint256 to a int256, revert on overflow
                      /// @param y The uint256 to be casted
                      /// @return z The casted integer, now type int256
                      function toInt256(uint256 y) internal pure returns (int256 z) {
                          require(y < 2**255);
                          z = int256(y);
                      }
                  }
                  // SPDX-License-Identifier: BUSL-1.1
                  pragma solidity >=0.5.0;
                  import './LowGasSafeMath.sol';
                  import './SafeCast.sol';
                  import './TickMath.sol';
                  import './LiquidityMath.sol';
                  /// @title Tick
                  /// @notice Contains functions for managing tick processes and relevant calculations
                  library Tick {
                      using LowGasSafeMath for int256;
                      using SafeCast for int256;
                      // info stored for each initialized individual tick
                      struct Info {
                          // the total position liquidity that references this tick
                          uint128 liquidityGross;
                          // amount of net liquidity added (subtracted) when tick is crossed from left to right (right to left),
                          int128 liquidityNet;
                          // fee growth per unit of liquidity on the _other_ side of this tick (relative to the current tick)
                          // only has relative meaning, not absolute — the value depends on when the tick is initialized
                          uint256 feeGrowthOutside0X128;
                          uint256 feeGrowthOutside1X128;
                          // the cumulative tick value on the other side of the tick
                          int56 tickCumulativeOutside;
                          // the seconds per unit of liquidity on the _other_ side of this tick (relative to the current tick)
                          // only has relative meaning, not absolute — the value depends on when the tick is initialized
                          uint160 secondsPerLiquidityOutsideX128;
                          // the seconds spent on the other side of the tick (relative to the current tick)
                          // only has relative meaning, not absolute — the value depends on when the tick is initialized
                          uint32 secondsOutside;
                          // true iff the tick is initialized, i.e. the value is exactly equivalent to the expression liquidityGross != 0
                          // these 8 bits are set to prevent fresh sstores when crossing newly initialized ticks
                          bool initialized;
                      }
                      /// @notice Derives max liquidity per tick from given tick spacing
                      /// @dev Executed within the pool constructor
                      /// @param tickSpacing The amount of required tick separation, realized in multiples of `tickSpacing`
                      ///     e.g., a tickSpacing of 3 requires ticks to be initialized every 3rd tick i.e., ..., -6, -3, 0, 3, 6, ...
                      /// @return The max liquidity per tick
                      function tickSpacingToMaxLiquidityPerTick(int24 tickSpacing) internal pure returns (uint128) {
                          int24 minTick = (TickMath.MIN_TICK / tickSpacing) * tickSpacing;
                          int24 maxTick = (TickMath.MAX_TICK / tickSpacing) * tickSpacing;
                          uint24 numTicks = uint24((maxTick - minTick) / tickSpacing) + 1;
                          return type(uint128).max / numTicks;
                      }
                      /// @notice Retrieves fee growth data
                      /// @param self The mapping containing all tick information for initialized ticks
                      /// @param tickLower The lower tick boundary of the position
                      /// @param tickUpper The upper tick boundary of the position
                      /// @param tickCurrent The current tick
                      /// @param feeGrowthGlobal0X128 The all-time global fee growth, per unit of liquidity, in token0
                      /// @param feeGrowthGlobal1X128 The all-time global fee growth, per unit of liquidity, in token1
                      /// @return feeGrowthInside0X128 The all-time fee growth in token0, per unit of liquidity, inside the position's tick boundaries
                      /// @return feeGrowthInside1X128 The all-time fee growth in token1, per unit of liquidity, inside the position's tick boundaries
                      function getFeeGrowthInside(
                          mapping(int24 => Tick.Info) storage self,
                          int24 tickLower,
                          int24 tickUpper,
                          int24 tickCurrent,
                          uint256 feeGrowthGlobal0X128,
                          uint256 feeGrowthGlobal1X128
                      ) internal view returns (uint256 feeGrowthInside0X128, uint256 feeGrowthInside1X128) {
                          Info storage lower = self[tickLower];
                          Info storage upper = self[tickUpper];
                          // calculate fee growth below
                          uint256 feeGrowthBelow0X128;
                          uint256 feeGrowthBelow1X128;
                          if (tickCurrent >= tickLower) {
                              feeGrowthBelow0X128 = lower.feeGrowthOutside0X128;
                              feeGrowthBelow1X128 = lower.feeGrowthOutside1X128;
                          } else {
                              feeGrowthBelow0X128 = feeGrowthGlobal0X128 - lower.feeGrowthOutside0X128;
                              feeGrowthBelow1X128 = feeGrowthGlobal1X128 - lower.feeGrowthOutside1X128;
                          }
                          // calculate fee growth above
                          uint256 feeGrowthAbove0X128;
                          uint256 feeGrowthAbove1X128;
                          if (tickCurrent < tickUpper) {
                              feeGrowthAbove0X128 = upper.feeGrowthOutside0X128;
                              feeGrowthAbove1X128 = upper.feeGrowthOutside1X128;
                          } else {
                              feeGrowthAbove0X128 = feeGrowthGlobal0X128 - upper.feeGrowthOutside0X128;
                              feeGrowthAbove1X128 = feeGrowthGlobal1X128 - upper.feeGrowthOutside1X128;
                          }
                          feeGrowthInside0X128 = feeGrowthGlobal0X128 - feeGrowthBelow0X128 - feeGrowthAbove0X128;
                          feeGrowthInside1X128 = feeGrowthGlobal1X128 - feeGrowthBelow1X128 - feeGrowthAbove1X128;
                      }
                      /// @notice Updates a tick and returns true if the tick was flipped from initialized to uninitialized, or vice versa
                      /// @param self The mapping containing all tick information for initialized ticks
                      /// @param tick The tick that will be updated
                      /// @param tickCurrent The current tick
                      /// @param liquidityDelta A new amount of liquidity to be added (subtracted) when tick is crossed from left to right (right to left)
                      /// @param feeGrowthGlobal0X128 The all-time global fee growth, per unit of liquidity, in token0
                      /// @param feeGrowthGlobal1X128 The all-time global fee growth, per unit of liquidity, in token1
                      /// @param secondsPerLiquidityCumulativeX128 The all-time seconds per max(1, liquidity) of the pool
                      /// @param time The current block timestamp cast to a uint32
                      /// @param upper true for updating a position's upper tick, or false for updating a position's lower tick
                      /// @param maxLiquidity The maximum liquidity allocation for a single tick
                      /// @return flipped Whether the tick was flipped from initialized to uninitialized, or vice versa
                      function update(
                          mapping(int24 => Tick.Info) storage self,
                          int24 tick,
                          int24 tickCurrent,
                          int128 liquidityDelta,
                          uint256 feeGrowthGlobal0X128,
                          uint256 feeGrowthGlobal1X128,
                          uint160 secondsPerLiquidityCumulativeX128,
                          int56 tickCumulative,
                          uint32 time,
                          bool upper,
                          uint128 maxLiquidity
                      ) internal returns (bool flipped) {
                          Tick.Info storage info = self[tick];
                          uint128 liquidityGrossBefore = info.liquidityGross;
                          uint128 liquidityGrossAfter = LiquidityMath.addDelta(liquidityGrossBefore, liquidityDelta);
                          require(liquidityGrossAfter <= maxLiquidity, 'LO');
                          flipped = (liquidityGrossAfter == 0) != (liquidityGrossBefore == 0);
                          if (liquidityGrossBefore == 0) {
                              // by convention, we assume that all growth before a tick was initialized happened _below_ the tick
                              if (tick <= tickCurrent) {
                                  info.feeGrowthOutside0X128 = feeGrowthGlobal0X128;
                                  info.feeGrowthOutside1X128 = feeGrowthGlobal1X128;
                                  info.secondsPerLiquidityOutsideX128 = secondsPerLiquidityCumulativeX128;
                                  info.tickCumulativeOutside = tickCumulative;
                                  info.secondsOutside = time;
                              }
                              info.initialized = true;
                          }
                          info.liquidityGross = liquidityGrossAfter;
                          // when the lower (upper) tick is crossed left to right (right to left), liquidity must be added (removed)
                          info.liquidityNet = upper
                              ? int256(info.liquidityNet).sub(liquidityDelta).toInt128()
                              : int256(info.liquidityNet).add(liquidityDelta).toInt128();
                      }
                      /// @notice Clears tick data
                      /// @param self The mapping containing all initialized tick information for initialized ticks
                      /// @param tick The tick that will be cleared
                      function clear(mapping(int24 => Tick.Info) storage self, int24 tick) internal {
                          delete self[tick];
                      }
                      /// @notice Transitions to next tick as needed by price movement
                      /// @param self The mapping containing all tick information for initialized ticks
                      /// @param tick The destination tick of the transition
                      /// @param feeGrowthGlobal0X128 The all-time global fee growth, per unit of liquidity, in token0
                      /// @param feeGrowthGlobal1X128 The all-time global fee growth, per unit of liquidity, in token1
                      /// @param secondsPerLiquidityCumulativeX128 The current seconds per liquidity
                      /// @param time The current block.timestamp
                      /// @return liquidityNet The amount of liquidity added (subtracted) when tick is crossed from left to right (right to left)
                      function cross(
                          mapping(int24 => Tick.Info) storage self,
                          int24 tick,
                          uint256 feeGrowthGlobal0X128,
                          uint256 feeGrowthGlobal1X128,
                          uint160 secondsPerLiquidityCumulativeX128,
                          int56 tickCumulative,
                          uint32 time
                      ) internal returns (int128 liquidityNet) {
                          Tick.Info storage info = self[tick];
                          info.feeGrowthOutside0X128 = feeGrowthGlobal0X128 - info.feeGrowthOutside0X128;
                          info.feeGrowthOutside1X128 = feeGrowthGlobal1X128 - info.feeGrowthOutside1X128;
                          info.secondsPerLiquidityOutsideX128 = secondsPerLiquidityCumulativeX128 - info.secondsPerLiquidityOutsideX128;
                          info.tickCumulativeOutside = tickCumulative - info.tickCumulativeOutside;
                          info.secondsOutside = time - info.secondsOutside;
                          liquidityNet = info.liquidityNet;
                      }
                  }
                  // SPDX-License-Identifier: BUSL-1.1
                  pragma solidity >=0.5.0;
                  import './BitMath.sol';
                  /// @title Packed tick initialized state library
                  /// @notice Stores a packed mapping of tick index to its initialized state
                  /// @dev The mapping uses int16 for keys since ticks are represented as int24 and there are 256 (2^8) values per word.
                  library TickBitmap {
                      /// @notice Computes the position in the mapping where the initialized bit for a tick lives
                      /// @param tick The tick for which to compute the position
                      /// @return wordPos The key in the mapping containing the word in which the bit is stored
                      /// @return bitPos The bit position in the word where the flag is stored
                      function position(int24 tick) private pure returns (int16 wordPos, uint8 bitPos) {
                          wordPos = int16(tick >> 8);
                          bitPos = uint8(tick % 256);
                      }
                      /// @notice Flips the initialized state for a given tick from false to true, or vice versa
                      /// @param self The mapping in which to flip the tick
                      /// @param tick The tick to flip
                      /// @param tickSpacing The spacing between usable ticks
                      function flipTick(
                          mapping(int16 => uint256) storage self,
                          int24 tick,
                          int24 tickSpacing
                      ) internal {
                          require(tick % tickSpacing == 0); // ensure that the tick is spaced
                          (int16 wordPos, uint8 bitPos) = position(tick / tickSpacing);
                          uint256 mask = 1 << bitPos;
                          self[wordPos] ^= mask;
                      }
                      /// @notice Returns the next initialized tick contained in the same word (or adjacent word) as the tick that is either
                      /// to the left (less than or equal to) or right (greater than) of the given tick
                      /// @param self The mapping in which to compute the next initialized tick
                      /// @param tick The starting tick
                      /// @param tickSpacing The spacing between usable ticks
                      /// @param lte Whether to search for the next initialized tick to the left (less than or equal to the starting tick)
                      /// @return next The next initialized or uninitialized tick up to 256 ticks away from the current tick
                      /// @return initialized Whether the next tick is initialized, as the function only searches within up to 256 ticks
                      function nextInitializedTickWithinOneWord(
                          mapping(int16 => uint256) storage self,
                          int24 tick,
                          int24 tickSpacing,
                          bool lte
                      ) internal view returns (int24 next, bool initialized) {
                          int24 compressed = tick / tickSpacing;
                          if (tick < 0 && tick % tickSpacing != 0) compressed--; // round towards negative infinity
                          if (lte) {
                              (int16 wordPos, uint8 bitPos) = position(compressed);
                              // all the 1s at or to the right of the current bitPos
                              uint256 mask = (1 << bitPos) - 1 + (1 << bitPos);
                              uint256 masked = self[wordPos] & mask;
                              // if there are no initialized ticks to the right of or at the current tick, return rightmost in the word
                              initialized = masked != 0;
                              // overflow/underflow is possible, but prevented externally by limiting both tickSpacing and tick
                              next = initialized
                                  ? (compressed - int24(bitPos - BitMath.mostSignificantBit(masked))) * tickSpacing
                                  : (compressed - int24(bitPos)) * tickSpacing;
                          } else {
                              // start from the word of the next tick, since the current tick state doesn't matter
                              (int16 wordPos, uint8 bitPos) = position(compressed + 1);
                              // all the 1s at or to the left of the bitPos
                              uint256 mask = ~((1 << bitPos) - 1);
                              uint256 masked = self[wordPos] & mask;
                              // if there are no initialized ticks to the left of the current tick, return leftmost in the word
                              initialized = masked != 0;
                              // overflow/underflow is possible, but prevented externally by limiting both tickSpacing and tick
                              next = initialized
                                  ? (compressed + 1 + int24(BitMath.leastSignificantBit(masked) - bitPos)) * tickSpacing
                                  : (compressed + 1 + int24(type(uint8).max - bitPos)) * tickSpacing;
                          }
                      }
                  }
                  // SPDX-License-Identifier: BUSL-1.1
                  pragma solidity >=0.5.0;
                  import './FullMath.sol';
                  import './FixedPoint128.sol';
                  import './LiquidityMath.sol';
                  /// @title Position
                  /// @notice Positions represent an owner address' liquidity between a lower and upper tick boundary
                  /// @dev Positions store additional state for tracking fees owed to the position
                  library Position {
                      // info stored for each user's position
                      struct Info {
                          // the amount of liquidity owned by this position
                          uint128 liquidity;
                          // fee growth per unit of liquidity as of the last update to liquidity or fees owed
                          uint256 feeGrowthInside0LastX128;
                          uint256 feeGrowthInside1LastX128;
                          // the fees owed to the position owner in token0/token1
                          uint128 tokensOwed0;
                          uint128 tokensOwed1;
                      }
                      /// @notice Returns the Info struct of a position, given an owner and position boundaries
                      /// @param self The mapping containing all user positions
                      /// @param owner The address of the position owner
                      /// @param tickLower The lower tick boundary of the position
                      /// @param tickUpper The upper tick boundary of the position
                      /// @return position The position info struct of the given owners' position
                      function get(
                          mapping(bytes32 => Info) storage self,
                          address owner,
                          int24 tickLower,
                          int24 tickUpper
                      ) internal view returns (Position.Info storage position) {
                          position = self[keccak256(abi.encodePacked(owner, tickLower, tickUpper))];
                      }
                      /// @notice Credits accumulated fees to a user's position
                      /// @param self The individual position to update
                      /// @param liquidityDelta The change in pool liquidity as a result of the position update
                      /// @param feeGrowthInside0X128 The all-time fee growth in token0, per unit of liquidity, inside the position's tick boundaries
                      /// @param feeGrowthInside1X128 The all-time fee growth in token1, per unit of liquidity, inside the position's tick boundaries
                      function update(
                          Info storage self,
                          int128 liquidityDelta,
                          uint256 feeGrowthInside0X128,
                          uint256 feeGrowthInside1X128
                      ) internal {
                          Info memory _self = self;
                          uint128 liquidityNext;
                          if (liquidityDelta == 0) {
                              require(_self.liquidity > 0, 'NP'); // disallow pokes for 0 liquidity positions
                              liquidityNext = _self.liquidity;
                          } else {
                              liquidityNext = LiquidityMath.addDelta(_self.liquidity, liquidityDelta);
                          }
                          // calculate accumulated fees
                          uint128 tokensOwed0 =
                              uint128(
                                  FullMath.mulDiv(
                                      feeGrowthInside0X128 - _self.feeGrowthInside0LastX128,
                                      _self.liquidity,
                                      FixedPoint128.Q128
                                  )
                              );
                          uint128 tokensOwed1 =
                              uint128(
                                  FullMath.mulDiv(
                                      feeGrowthInside1X128 - _self.feeGrowthInside1LastX128,
                                      _self.liquidity,
                                      FixedPoint128.Q128
                                  )
                              );
                          // update the position
                          if (liquidityDelta != 0) self.liquidity = liquidityNext;
                          self.feeGrowthInside0LastX128 = feeGrowthInside0X128;
                          self.feeGrowthInside1LastX128 = feeGrowthInside1X128;
                          if (tokensOwed0 > 0 || tokensOwed1 > 0) {
                              // overflow is acceptable, have to withdraw before you hit type(uint128).max fees
                              self.tokensOwed0 += tokensOwed0;
                              self.tokensOwed1 += tokensOwed1;
                          }
                      }
                  }
                  // SPDX-License-Identifier: BUSL-1.1
                  pragma solidity >=0.5.0;
                  /// @title Oracle
                  /// @notice Provides price and liquidity data useful for a wide variety of system designs
                  /// @dev Instances of stored oracle data, "observations", are collected in the oracle array
                  /// Every pool is initialized with an oracle array length of 1. Anyone can pay the SSTOREs to increase the
                  /// maximum length of the oracle array. New slots will be added when the array is fully populated.
                  /// Observations are overwritten when the full length of the oracle array is populated.
                  /// The most recent observation is available, independent of the length of the oracle array, by passing 0 to observe()
                  library Oracle {
                      struct Observation {
                          // the block timestamp of the observation
                          uint32 blockTimestamp;
                          // the tick accumulator, i.e. tick * time elapsed since the pool was first initialized
                          int56 tickCumulative;
                          // the seconds per liquidity, i.e. seconds elapsed / max(1, liquidity) since the pool was first initialized
                          uint160 secondsPerLiquidityCumulativeX128;
                          // whether or not the observation is initialized
                          bool initialized;
                      }
                      /// @notice Transforms a previous observation into a new observation, given the passage of time and the current tick and liquidity values
                      /// @dev blockTimestamp _must_ be chronologically equal to or greater than last.blockTimestamp, safe for 0 or 1 overflows
                      /// @param last The specified observation to be transformed
                      /// @param blockTimestamp The timestamp of the new observation
                      /// @param tick The active tick at the time of the new observation
                      /// @param liquidity The total in-range liquidity at the time of the new observation
                      /// @return Observation The newly populated observation
                      function transform(
                          Observation memory last,
                          uint32 blockTimestamp,
                          int24 tick,
                          uint128 liquidity
                      ) private pure returns (Observation memory) {
                          uint32 delta = blockTimestamp - last.blockTimestamp;
                          return
                              Observation({
                                  blockTimestamp: blockTimestamp,
                                  tickCumulative: last.tickCumulative + int56(tick) * delta,
                                  secondsPerLiquidityCumulativeX128: last.secondsPerLiquidityCumulativeX128 +
                                      ((uint160(delta) << 128) / (liquidity > 0 ? liquidity : 1)),
                                  initialized: true
                              });
                      }
                      /// @notice Initialize the oracle array by writing the first slot. Called once for the lifecycle of the observations array
                      /// @param self The stored oracle array
                      /// @param time The time of the oracle initialization, via block.timestamp truncated to uint32
                      /// @return cardinality The number of populated elements in the oracle array
                      /// @return cardinalityNext The new length of the oracle array, independent of population
                      function initialize(Observation[65535] storage self, uint32 time)
                          internal
                          returns (uint16 cardinality, uint16 cardinalityNext)
                      {
                          self[0] = Observation({
                              blockTimestamp: time,
                              tickCumulative: 0,
                              secondsPerLiquidityCumulativeX128: 0,
                              initialized: true
                          });
                          return (1, 1);
                      }
                      /// @notice Writes an oracle observation to the array
                      /// @dev Writable at most once per block. Index represents the most recently written element. cardinality and index must be tracked externally.
                      /// If the index is at the end of the allowable array length (according to cardinality), and the next cardinality
                      /// is greater than the current one, cardinality may be increased. This restriction is created to preserve ordering.
                      /// @param self The stored oracle array
                      /// @param index The index of the observation that was most recently written to the observations array
                      /// @param blockTimestamp The timestamp of the new observation
                      /// @param tick The active tick at the time of the new observation
                      /// @param liquidity The total in-range liquidity at the time of the new observation
                      /// @param cardinality The number of populated elements in the oracle array
                      /// @param cardinalityNext The new length of the oracle array, independent of population
                      /// @return indexUpdated The new index of the most recently written element in the oracle array
                      /// @return cardinalityUpdated The new cardinality of the oracle array
                      function write(
                          Observation[65535] storage self,
                          uint16 index,
                          uint32 blockTimestamp,
                          int24 tick,
                          uint128 liquidity,
                          uint16 cardinality,
                          uint16 cardinalityNext
                      ) internal returns (uint16 indexUpdated, uint16 cardinalityUpdated) {
                          Observation memory last = self[index];
                          // early return if we've already written an observation this block
                          if (last.blockTimestamp == blockTimestamp) return (index, cardinality);
                          // if the conditions are right, we can bump the cardinality
                          if (cardinalityNext > cardinality && index == (cardinality - 1)) {
                              cardinalityUpdated = cardinalityNext;
                          } else {
                              cardinalityUpdated = cardinality;
                          }
                          indexUpdated = (index + 1) % cardinalityUpdated;
                          self[indexUpdated] = transform(last, blockTimestamp, tick, liquidity);
                      }
                      /// @notice Prepares the oracle array to store up to `next` observations
                      /// @param self The stored oracle array
                      /// @param current The current next cardinality of the oracle array
                      /// @param next The proposed next cardinality which will be populated in the oracle array
                      /// @return next The next cardinality which will be populated in the oracle array
                      function grow(
                          Observation[65535] storage self,
                          uint16 current,
                          uint16 next
                      ) internal returns (uint16) {
                          require(current > 0, 'I');
                          // no-op if the passed next value isn't greater than the current next value
                          if (next <= current) return current;
                          // store in each slot to prevent fresh SSTOREs in swaps
                          // this data will not be used because the initialized boolean is still false
                          for (uint16 i = current; i < next; i++) self[i].blockTimestamp = 1;
                          return next;
                      }
                      /// @notice comparator for 32-bit timestamps
                      /// @dev safe for 0 or 1 overflows, a and b _must_ be chronologically before or equal to time
                      /// @param time A timestamp truncated to 32 bits
                      /// @param a A comparison timestamp from which to determine the relative position of `time`
                      /// @param b From which to determine the relative position of `time`
                      /// @return bool Whether `a` is chronologically <= `b`
                      function lte(
                          uint32 time,
                          uint32 a,
                          uint32 b
                      ) private pure returns (bool) {
                          // if there hasn't been overflow, no need to adjust
                          if (a <= time && b <= time) return a <= b;
                          uint256 aAdjusted = a > time ? a : a + 2**32;
                          uint256 bAdjusted = b > time ? b : b + 2**32;
                          return aAdjusted <= bAdjusted;
                      }
                      /// @notice Fetches the observations beforeOrAt and atOrAfter a target, i.e. where [beforeOrAt, atOrAfter] is satisfied.
                      /// The result may be the same observation, or adjacent observations.
                      /// @dev The answer must be contained in the array, used when the target is located within the stored observation
                      /// boundaries: older than the most recent observation and younger, or the same age as, the oldest observation
                      /// @param self The stored oracle array
                      /// @param time The current block.timestamp
                      /// @param target The timestamp at which the reserved observation should be for
                      /// @param index The index of the observation that was most recently written to the observations array
                      /// @param cardinality The number of populated elements in the oracle array
                      /// @return beforeOrAt The observation recorded before, or at, the target
                      /// @return atOrAfter The observation recorded at, or after, the target
                      function binarySearch(
                          Observation[65535] storage self,
                          uint32 time,
                          uint32 target,
                          uint16 index,
                          uint16 cardinality
                      ) private view returns (Observation memory beforeOrAt, Observation memory atOrAfter) {
                          uint256 l = (index + 1) % cardinality; // oldest observation
                          uint256 r = l + cardinality - 1; // newest observation
                          uint256 i;
                          while (true) {
                              i = (l + r) / 2;
                              beforeOrAt = self[i % cardinality];
                              // we've landed on an uninitialized tick, keep searching higher (more recently)
                              if (!beforeOrAt.initialized) {
                                  l = i + 1;
                                  continue;
                              }
                              atOrAfter = self[(i + 1) % cardinality];
                              bool targetAtOrAfter = lte(time, beforeOrAt.blockTimestamp, target);
                              // check if we've found the answer!
                              if (targetAtOrAfter && lte(time, target, atOrAfter.blockTimestamp)) break;
                              if (!targetAtOrAfter) r = i - 1;
                              else l = i + 1;
                          }
                      }
                      /// @notice Fetches the observations beforeOrAt and atOrAfter a given target, i.e. where [beforeOrAt, atOrAfter] is satisfied
                      /// @dev Assumes there is at least 1 initialized observation.
                      /// Used by observeSingle() to compute the counterfactual accumulator values as of a given block timestamp.
                      /// @param self The stored oracle array
                      /// @param time The current block.timestamp
                      /// @param target The timestamp at which the reserved observation should be for
                      /// @param tick The active tick at the time of the returned or simulated observation
                      /// @param index The index of the observation that was most recently written to the observations array
                      /// @param liquidity The total pool liquidity at the time of the call
                      /// @param cardinality The number of populated elements in the oracle array
                      /// @return beforeOrAt The observation which occurred at, or before, the given timestamp
                      /// @return atOrAfter The observation which occurred at, or after, the given timestamp
                      function getSurroundingObservations(
                          Observation[65535] storage self,
                          uint32 time,
                          uint32 target,
                          int24 tick,
                          uint16 index,
                          uint128 liquidity,
                          uint16 cardinality
                      ) private view returns (Observation memory beforeOrAt, Observation memory atOrAfter) {
                          // optimistically set before to the newest observation
                          beforeOrAt = self[index];
                          // if the target is chronologically at or after the newest observation, we can early return
                          if (lte(time, beforeOrAt.blockTimestamp, target)) {
                              if (beforeOrAt.blockTimestamp == target) {
                                  // if newest observation equals target, we're in the same block, so we can ignore atOrAfter
                                  return (beforeOrAt, atOrAfter);
                              } else {
                                  // otherwise, we need to transform
                                  return (beforeOrAt, transform(beforeOrAt, target, tick, liquidity));
                              }
                          }
                          // now, set before to the oldest observation
                          beforeOrAt = self[(index + 1) % cardinality];
                          if (!beforeOrAt.initialized) beforeOrAt = self[0];
                          // ensure that the target is chronologically at or after the oldest observation
                          require(lte(time, beforeOrAt.blockTimestamp, target), 'OLD');
                          // if we've reached this point, we have to binary search
                          return binarySearch(self, time, target, index, cardinality);
                      }
                      /// @dev Reverts if an observation at or before the desired observation timestamp does not exist.
                      /// 0 may be passed as `secondsAgo' to return the current cumulative values.
                      /// If called with a timestamp falling between two observations, returns the counterfactual accumulator values
                      /// at exactly the timestamp between the two observations.
                      /// @param self The stored oracle array
                      /// @param time The current block timestamp
                      /// @param secondsAgo The amount of time to look back, in seconds, at which point to return an observation
                      /// @param tick The current tick
                      /// @param index The index of the observation that was most recently written to the observations array
                      /// @param liquidity The current in-range pool liquidity
                      /// @param cardinality The number of populated elements in the oracle array
                      /// @return tickCumulative The tick * time elapsed since the pool was first initialized, as of `secondsAgo`
                      /// @return secondsPerLiquidityCumulativeX128 The time elapsed / max(1, liquidity) since the pool was first initialized, as of `secondsAgo`
                      function observeSingle(
                          Observation[65535] storage self,
                          uint32 time,
                          uint32 secondsAgo,
                          int24 tick,
                          uint16 index,
                          uint128 liquidity,
                          uint16 cardinality
                      ) internal view returns (int56 tickCumulative, uint160 secondsPerLiquidityCumulativeX128) {
                          if (secondsAgo == 0) {
                              Observation memory last = self[index];
                              if (last.blockTimestamp != time) last = transform(last, time, tick, liquidity);
                              return (last.tickCumulative, last.secondsPerLiquidityCumulativeX128);
                          }
                          uint32 target = time - secondsAgo;
                          (Observation memory beforeOrAt, Observation memory atOrAfter) =
                              getSurroundingObservations(self, time, target, tick, index, liquidity, cardinality);
                          if (target == beforeOrAt.blockTimestamp) {
                              // we're at the left boundary
                              return (beforeOrAt.tickCumulative, beforeOrAt.secondsPerLiquidityCumulativeX128);
                          } else if (target == atOrAfter.blockTimestamp) {
                              // we're at the right boundary
                              return (atOrAfter.tickCumulative, atOrAfter.secondsPerLiquidityCumulativeX128);
                          } else {
                              // we're in the middle
                              uint32 observationTimeDelta = atOrAfter.blockTimestamp - beforeOrAt.blockTimestamp;
                              uint32 targetDelta = target - beforeOrAt.blockTimestamp;
                              return (
                                  beforeOrAt.tickCumulative +
                                      ((atOrAfter.tickCumulative - beforeOrAt.tickCumulative) / observationTimeDelta) *
                                      targetDelta,
                                  beforeOrAt.secondsPerLiquidityCumulativeX128 +
                                      uint160(
                                          (uint256(
                                              atOrAfter.secondsPerLiquidityCumulativeX128 - beforeOrAt.secondsPerLiquidityCumulativeX128
                                          ) * targetDelta) / observationTimeDelta
                                      )
                              );
                          }
                      }
                      /// @notice Returns the accumulator values as of each time seconds ago from the given time in the array of `secondsAgos`
                      /// @dev Reverts if `secondsAgos` > oldest observation
                      /// @param self The stored oracle array
                      /// @param time The current block.timestamp
                      /// @param secondsAgos Each amount of time to look back, in seconds, at which point to return an observation
                      /// @param tick The current tick
                      /// @param index The index of the observation that was most recently written to the observations array
                      /// @param liquidity The current in-range pool liquidity
                      /// @param cardinality The number of populated elements in the oracle array
                      /// @return tickCumulatives The tick * time elapsed since the pool was first initialized, as of each `secondsAgo`
                      /// @return secondsPerLiquidityCumulativeX128s The cumulative seconds / max(1, liquidity) since the pool was first initialized, as of each `secondsAgo`
                      function observe(
                          Observation[65535] storage self,
                          uint32 time,
                          uint32[] memory secondsAgos,
                          int24 tick,
                          uint16 index,
                          uint128 liquidity,
                          uint16 cardinality
                      ) internal view returns (int56[] memory tickCumulatives, uint160[] memory secondsPerLiquidityCumulativeX128s) {
                          require(cardinality > 0, 'I');
                          tickCumulatives = new int56[](secondsAgos.length);
                          secondsPerLiquidityCumulativeX128s = new uint160[](secondsAgos.length);
                          for (uint256 i = 0; i < secondsAgos.length; i++) {
                              (tickCumulatives[i], secondsPerLiquidityCumulativeX128s[i]) = observeSingle(
                                  self,
                                  time,
                                  secondsAgos[i],
                                  tick,
                                  index,
                                  liquidity,
                                  cardinality
                              );
                          }
                      }
                  }
                  // SPDX-License-Identifier: MIT
                  pragma solidity >=0.4.0;
                  /// @title Contains 512-bit math functions
                  /// @notice Facilitates multiplication and division that can have overflow of an intermediate value without any loss of precision
                  /// @dev Handles "phantom overflow" i.e., allows multiplication and division where an intermediate value overflows 256 bits
                  library FullMath {
                      /// @notice Calculates floor(a×b÷denominator) with full precision. Throws if result overflows a uint256 or denominator == 0
                      /// @param a The multiplicand
                      /// @param b The multiplier
                      /// @param denominator The divisor
                      /// @return result The 256-bit result
                      /// @dev Credit to Remco Bloemen under MIT license https://xn--2-umb.com/21/muldiv
                      function mulDiv(
                          uint256 a,
                          uint256 b,
                          uint256 denominator
                      ) internal pure returns (uint256 result) {
                          // 512-bit multiply [prod1 prod0] = a * b
                          // Compute the product mod 2**256 and mod 2**256 - 1
                          // then use the Chinese Remainder Theorem to reconstruct
                          // the 512 bit result. The result is stored in two 256
                          // variables such that product = prod1 * 2**256 + prod0
                          uint256 prod0; // Least significant 256 bits of the product
                          uint256 prod1; // Most significant 256 bits of the product
                          assembly {
                              let mm := mulmod(a, b, not(0))
                              prod0 := mul(a, b)
                              prod1 := sub(sub(mm, prod0), lt(mm, prod0))
                          }
                          // Handle non-overflow cases, 256 by 256 division
                          if (prod1 == 0) {
                              require(denominator > 0);
                              assembly {
                                  result := div(prod0, denominator)
                              }
                              return result;
                          }
                          // Make sure the result is less than 2**256.
                          // Also prevents denominator == 0
                          require(denominator > prod1);
                          ///////////////////////////////////////////////
                          // 512 by 256 division.
                          ///////////////////////////////////////////////
                          // Make division exact by subtracting the remainder from [prod1 prod0]
                          // Compute remainder using mulmod
                          uint256 remainder;
                          assembly {
                              remainder := mulmod(a, b, denominator)
                          }
                          // Subtract 256 bit number from 512 bit number
                          assembly {
                              prod1 := sub(prod1, gt(remainder, prod0))
                              prod0 := sub(prod0, remainder)
                          }
                          // Factor powers of two out of denominator
                          // Compute largest power of two divisor of denominator.
                          // Always >= 1.
                          uint256 twos = -denominator & denominator;
                          // Divide denominator by power of two
                          assembly {
                              denominator := div(denominator, twos)
                          }
                          // Divide [prod1 prod0] by the factors of two
                          assembly {
                              prod0 := div(prod0, twos)
                          }
                          // Shift in bits from prod1 into prod0. For this we need
                          // to flip `twos` such that it is 2**256 / twos.
                          // If twos is zero, then it becomes one
                          assembly {
                              twos := add(div(sub(0, twos), twos), 1)
                          }
                          prod0 |= prod1 * twos;
                          // Invert denominator mod 2**256
                          // Now that denominator is an odd number, it has an inverse
                          // modulo 2**256 such that denominator * inv = 1 mod 2**256.
                          // Compute the inverse by starting with a seed that is correct
                          // correct for four bits. That is, denominator * inv = 1 mod 2**4
                          uint256 inv = (3 * denominator) ^ 2;
                          // Now use Newton-Raphson iteration to improve the precision.
                          // Thanks to Hensel's lifting lemma, this also works in modular
                          // arithmetic, doubling the correct bits in each step.
                          inv *= 2 - denominator * inv; // inverse mod 2**8
                          inv *= 2 - denominator * inv; // inverse mod 2**16
                          inv *= 2 - denominator * inv; // inverse mod 2**32
                          inv *= 2 - denominator * inv; // inverse mod 2**64
                          inv *= 2 - denominator * inv; // inverse mod 2**128
                          inv *= 2 - denominator * inv; // inverse mod 2**256
                          // Because the division is now exact we can divide by multiplying
                          // with the modular inverse of denominator. This will give us the
                          // correct result modulo 2**256. Since the precoditions guarantee
                          // that the outcome is less than 2**256, this is the final result.
                          // We don't need to compute the high bits of the result and prod1
                          // is no longer required.
                          result = prod0 * inv;
                          return result;
                      }
                      /// @notice Calculates ceil(a×b÷denominator) with full precision. Throws if result overflows a uint256 or denominator == 0
                      /// @param a The multiplicand
                      /// @param b The multiplier
                      /// @param denominator The divisor
                      /// @return result The 256-bit result
                      function mulDivRoundingUp(
                          uint256 a,
                          uint256 b,
                          uint256 denominator
                      ) internal pure returns (uint256 result) {
                          result = mulDiv(a, b, denominator);
                          if (mulmod(a, b, denominator) > 0) {
                              require(result < type(uint256).max);
                              result++;
                          }
                      }
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.4.0;
                  /// @title FixedPoint128
                  /// @notice A library for handling binary fixed point numbers, see https://en.wikipedia.org/wiki/Q_(number_format)
                  library FixedPoint128 {
                      uint256 internal constant Q128 = 0x100000000000000000000000000000000;
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.6.0;
                  import '../interfaces/IERC20Minimal.sol';
                  /// @title TransferHelper
                  /// @notice Contains helper methods for interacting with ERC20 tokens that do not consistently return true/false
                  library TransferHelper {
                      /// @notice Transfers tokens from msg.sender to a recipient
                      /// @dev Calls transfer on token contract, errors with TF if transfer fails
                      /// @param token The contract address of the token which will be transferred
                      /// @param to The recipient of the transfer
                      /// @param value The value of the transfer
                      function safeTransfer(
                          address token,
                          address to,
                          uint256 value
                      ) internal {
                          (bool success, bytes memory data) =
                              token.call(abi.encodeWithSelector(IERC20Minimal.transfer.selector, to, value));
                          require(success && (data.length == 0 || abi.decode(data, (bool))), 'TF');
                      }
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.5.0;
                  /// @title Math library for computing sqrt prices from ticks and vice versa
                  /// @notice Computes sqrt price for ticks of size 1.0001, i.e. sqrt(1.0001^tick) as fixed point Q64.96 numbers. Supports
                  /// prices between 2**-128 and 2**128
                  library TickMath {
                      /// @dev The minimum tick that may be passed to #getSqrtRatioAtTick computed from log base 1.0001 of 2**-128
                      int24 internal constant MIN_TICK = -887272;
                      /// @dev The maximum tick that may be passed to #getSqrtRatioAtTick computed from log base 1.0001 of 2**128
                      int24 internal constant MAX_TICK = -MIN_TICK;
                      /// @dev The minimum value that can be returned from #getSqrtRatioAtTick. Equivalent to getSqrtRatioAtTick(MIN_TICK)
                      uint160 internal constant MIN_SQRT_RATIO = 4295128739;
                      /// @dev The maximum value that can be returned from #getSqrtRatioAtTick. Equivalent to getSqrtRatioAtTick(MAX_TICK)
                      uint160 internal constant MAX_SQRT_RATIO = 1461446703485210103287273052203988822378723970342;
                      /// @notice Calculates sqrt(1.0001^tick) * 2^96
                      /// @dev Throws if |tick| > max tick
                      /// @param tick The input tick for the above formula
                      /// @return sqrtPriceX96 A Fixed point Q64.96 number representing the sqrt of the ratio of the two assets (token1/token0)
                      /// at the given tick
                      function getSqrtRatioAtTick(int24 tick) internal pure returns (uint160 sqrtPriceX96) {
                          uint256 absTick = tick < 0 ? uint256(-int256(tick)) : uint256(int256(tick));
                          require(absTick <= uint256(MAX_TICK), 'T');
                          uint256 ratio = absTick & 0x1 != 0 ? 0xfffcb933bd6fad37aa2d162d1a594001 : 0x100000000000000000000000000000000;
                          if (absTick & 0x2 != 0) ratio = (ratio * 0xfff97272373d413259a46990580e213a) >> 128;
                          if (absTick & 0x4 != 0) ratio = (ratio * 0xfff2e50f5f656932ef12357cf3c7fdcc) >> 128;
                          if (absTick & 0x8 != 0) ratio = (ratio * 0xffe5caca7e10e4e61c3624eaa0941cd0) >> 128;
                          if (absTick & 0x10 != 0) ratio = (ratio * 0xffcb9843d60f6159c9db58835c926644) >> 128;
                          if (absTick & 0x20 != 0) ratio = (ratio * 0xff973b41fa98c081472e6896dfb254c0) >> 128;
                          if (absTick & 0x40 != 0) ratio = (ratio * 0xff2ea16466c96a3843ec78b326b52861) >> 128;
                          if (absTick & 0x80 != 0) ratio = (ratio * 0xfe5dee046a99a2a811c461f1969c3053) >> 128;
                          if (absTick & 0x100 != 0) ratio = (ratio * 0xfcbe86c7900a88aedcffc83b479aa3a4) >> 128;
                          if (absTick & 0x200 != 0) ratio = (ratio * 0xf987a7253ac413176f2b074cf7815e54) >> 128;
                          if (absTick & 0x400 != 0) ratio = (ratio * 0xf3392b0822b70005940c7a398e4b70f3) >> 128;
                          if (absTick & 0x800 != 0) ratio = (ratio * 0xe7159475a2c29b7443b29c7fa6e889d9) >> 128;
                          if (absTick & 0x1000 != 0) ratio = (ratio * 0xd097f3bdfd2022b8845ad8f792aa5825) >> 128;
                          if (absTick & 0x2000 != 0) ratio = (ratio * 0xa9f746462d870fdf8a65dc1f90e061e5) >> 128;
                          if (absTick & 0x4000 != 0) ratio = (ratio * 0x70d869a156d2a1b890bb3df62baf32f7) >> 128;
                          if (absTick & 0x8000 != 0) ratio = (ratio * 0x31be135f97d08fd981231505542fcfa6) >> 128;
                          if (absTick & 0x10000 != 0) ratio = (ratio * 0x9aa508b5b7a84e1c677de54f3e99bc9) >> 128;
                          if (absTick & 0x20000 != 0) ratio = (ratio * 0x5d6af8dedb81196699c329225ee604) >> 128;
                          if (absTick & 0x40000 != 0) ratio = (ratio * 0x2216e584f5fa1ea926041bedfe98) >> 128;
                          if (absTick & 0x80000 != 0) ratio = (ratio * 0x48a170391f7dc42444e8fa2) >> 128;
                          if (tick > 0) ratio = type(uint256).max / ratio;
                          // this divides by 1<<32 rounding up to go from a Q128.128 to a Q128.96.
                          // we then downcast because we know the result always fits within 160 bits due to our tick input constraint
                          // we round up in the division so getTickAtSqrtRatio of the output price is always consistent
                          sqrtPriceX96 = uint160((ratio >> 32) + (ratio % (1 << 32) == 0 ? 0 : 1));
                      }
                      /// @notice Calculates the greatest tick value such that getRatioAtTick(tick) <= ratio
                      /// @dev Throws in case sqrtPriceX96 < MIN_SQRT_RATIO, as MIN_SQRT_RATIO is the lowest value getRatioAtTick may
                      /// ever return.
                      /// @param sqrtPriceX96 The sqrt ratio for which to compute the tick as a Q64.96
                      /// @return tick The greatest tick for which the ratio is less than or equal to the input ratio
                      function getTickAtSqrtRatio(uint160 sqrtPriceX96) internal pure returns (int24 tick) {
                          // second inequality must be < because the price can never reach the price at the max tick
                          require(sqrtPriceX96 >= MIN_SQRT_RATIO && sqrtPriceX96 < MAX_SQRT_RATIO, 'R');
                          uint256 ratio = uint256(sqrtPriceX96) << 32;
                          uint256 r = ratio;
                          uint256 msb = 0;
                          assembly {
                              let f := shl(7, gt(r, 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF))
                              msb := or(msb, f)
                              r := shr(f, r)
                          }
                          assembly {
                              let f := shl(6, gt(r, 0xFFFFFFFFFFFFFFFF))
                              msb := or(msb, f)
                              r := shr(f, r)
                          }
                          assembly {
                              let f := shl(5, gt(r, 0xFFFFFFFF))
                              msb := or(msb, f)
                              r := shr(f, r)
                          }
                          assembly {
                              let f := shl(4, gt(r, 0xFFFF))
                              msb := or(msb, f)
                              r := shr(f, r)
                          }
                          assembly {
                              let f := shl(3, gt(r, 0xFF))
                              msb := or(msb, f)
                              r := shr(f, r)
                          }
                          assembly {
                              let f := shl(2, gt(r, 0xF))
                              msb := or(msb, f)
                              r := shr(f, r)
                          }
                          assembly {
                              let f := shl(1, gt(r, 0x3))
                              msb := or(msb, f)
                              r := shr(f, r)
                          }
                          assembly {
                              let f := gt(r, 0x1)
                              msb := or(msb, f)
                          }
                          if (msb >= 128) r = ratio >> (msb - 127);
                          else r = ratio << (127 - msb);
                          int256 log_2 = (int256(msb) - 128) << 64;
                          assembly {
                              r := shr(127, mul(r, r))
                              let f := shr(128, r)
                              log_2 := or(log_2, shl(63, f))
                              r := shr(f, r)
                          }
                          assembly {
                              r := shr(127, mul(r, r))
                              let f := shr(128, r)
                              log_2 := or(log_2, shl(62, f))
                              r := shr(f, r)
                          }
                          assembly {
                              r := shr(127, mul(r, r))
                              let f := shr(128, r)
                              log_2 := or(log_2, shl(61, f))
                              r := shr(f, r)
                          }
                          assembly {
                              r := shr(127, mul(r, r))
                              let f := shr(128, r)
                              log_2 := or(log_2, shl(60, f))
                              r := shr(f, r)
                          }
                          assembly {
                              r := shr(127, mul(r, r))
                              let f := shr(128, r)
                              log_2 := or(log_2, shl(59, f))
                              r := shr(f, r)
                          }
                          assembly {
                              r := shr(127, mul(r, r))
                              let f := shr(128, r)
                              log_2 := or(log_2, shl(58, f))
                              r := shr(f, r)
                          }
                          assembly {
                              r := shr(127, mul(r, r))
                              let f := shr(128, r)
                              log_2 := or(log_2, shl(57, f))
                              r := shr(f, r)
                          }
                          assembly {
                              r := shr(127, mul(r, r))
                              let f := shr(128, r)
                              log_2 := or(log_2, shl(56, f))
                              r := shr(f, r)
                          }
                          assembly {
                              r := shr(127, mul(r, r))
                              let f := shr(128, r)
                              log_2 := or(log_2, shl(55, f))
                              r := shr(f, r)
                          }
                          assembly {
                              r := shr(127, mul(r, r))
                              let f := shr(128, r)
                              log_2 := or(log_2, shl(54, f))
                              r := shr(f, r)
                          }
                          assembly {
                              r := shr(127, mul(r, r))
                              let f := shr(128, r)
                              log_2 := or(log_2, shl(53, f))
                              r := shr(f, r)
                          }
                          assembly {
                              r := shr(127, mul(r, r))
                              let f := shr(128, r)
                              log_2 := or(log_2, shl(52, f))
                              r := shr(f, r)
                          }
                          assembly {
                              r := shr(127, mul(r, r))
                              let f := shr(128, r)
                              log_2 := or(log_2, shl(51, f))
                              r := shr(f, r)
                          }
                          assembly {
                              r := shr(127, mul(r, r))
                              let f := shr(128, r)
                              log_2 := or(log_2, shl(50, f))
                          }
                          int256 log_sqrt10001 = log_2 * 255738958999603826347141; // 128.128 number
                          int24 tickLow = int24((log_sqrt10001 - 3402992956809132418596140100660247210) >> 128);
                          int24 tickHi = int24((log_sqrt10001 + 291339464771989622907027621153398088495) >> 128);
                          tick = tickLow == tickHi ? tickLow : getSqrtRatioAtTick(tickHi) <= sqrtPriceX96 ? tickHi : tickLow;
                      }
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.5.0;
                  /// @title Math library for liquidity
                  library LiquidityMath {
                      /// @notice Add a signed liquidity delta to liquidity and revert if it overflows or underflows
                      /// @param x The liquidity before change
                      /// @param y The delta by which liquidity should be changed
                      /// @return z The liquidity delta
                      function addDelta(uint128 x, int128 y) internal pure returns (uint128 z) {
                          if (y < 0) {
                              require((z = x - uint128(-y)) < x, 'LS');
                          } else {
                              require((z = x + uint128(y)) >= x, 'LA');
                          }
                      }
                  }
                  // SPDX-License-Identifier: BUSL-1.1
                  pragma solidity >=0.5.0;
                  import './LowGasSafeMath.sol';
                  import './SafeCast.sol';
                  import './FullMath.sol';
                  import './UnsafeMath.sol';
                  import './FixedPoint96.sol';
                  /// @title Functions based on Q64.96 sqrt price and liquidity
                  /// @notice Contains the math that uses square root of price as a Q64.96 and liquidity to compute deltas
                  library SqrtPriceMath {
                      using LowGasSafeMath for uint256;
                      using SafeCast for uint256;
                      /// @notice Gets the next sqrt price given a delta of token0
                      /// @dev Always rounds up, because in the exact output case (increasing price) we need to move the price at least
                      /// far enough to get the desired output amount, and in the exact input case (decreasing price) we need to move the
                      /// price less in order to not send too much output.
                      /// The most precise formula for this is liquidity * sqrtPX96 / (liquidity +- amount * sqrtPX96),
                      /// if this is impossible because of overflow, we calculate liquidity / (liquidity / sqrtPX96 +- amount).
                      /// @param sqrtPX96 The starting price, i.e. before accounting for the token0 delta
                      /// @param liquidity The amount of usable liquidity
                      /// @param amount How much of token0 to add or remove from virtual reserves
                      /// @param add Whether to add or remove the amount of token0
                      /// @return The price after adding or removing amount, depending on add
                      function getNextSqrtPriceFromAmount0RoundingUp(
                          uint160 sqrtPX96,
                          uint128 liquidity,
                          uint256 amount,
                          bool add
                      ) internal pure returns (uint160) {
                          // we short circuit amount == 0 because the result is otherwise not guaranteed to equal the input price
                          if (amount == 0) return sqrtPX96;
                          uint256 numerator1 = uint256(liquidity) << FixedPoint96.RESOLUTION;
                          if (add) {
                              uint256 product;
                              if ((product = amount * sqrtPX96) / amount == sqrtPX96) {
                                  uint256 denominator = numerator1 + product;
                                  if (denominator >= numerator1)
                                      // always fits in 160 bits
                                      return uint160(FullMath.mulDivRoundingUp(numerator1, sqrtPX96, denominator));
                              }
                              return uint160(UnsafeMath.divRoundingUp(numerator1, (numerator1 / sqrtPX96).add(amount)));
                          } else {
                              uint256 product;
                              // if the product overflows, we know the denominator underflows
                              // in addition, we must check that the denominator does not underflow
                              require((product = amount * sqrtPX96) / amount == sqrtPX96 && numerator1 > product);
                              uint256 denominator = numerator1 - product;
                              return FullMath.mulDivRoundingUp(numerator1, sqrtPX96, denominator).toUint160();
                          }
                      }
                      /// @notice Gets the next sqrt price given a delta of token1
                      /// @dev Always rounds down, because in the exact output case (decreasing price) we need to move the price at least
                      /// far enough to get the desired output amount, and in the exact input case (increasing price) we need to move the
                      /// price less in order to not send too much output.
                      /// The formula we compute is within <1 wei of the lossless version: sqrtPX96 +- amount / liquidity
                      /// @param sqrtPX96 The starting price, i.e., before accounting for the token1 delta
                      /// @param liquidity The amount of usable liquidity
                      /// @param amount How much of token1 to add, or remove, from virtual reserves
                      /// @param add Whether to add, or remove, the amount of token1
                      /// @return The price after adding or removing `amount`
                      function getNextSqrtPriceFromAmount1RoundingDown(
                          uint160 sqrtPX96,
                          uint128 liquidity,
                          uint256 amount,
                          bool add
                      ) internal pure returns (uint160) {
                          // if we're adding (subtracting), rounding down requires rounding the quotient down (up)
                          // in both cases, avoid a mulDiv for most inputs
                          if (add) {
                              uint256 quotient =
                                  (
                                      amount <= type(uint160).max
                                          ? (amount << FixedPoint96.RESOLUTION) / liquidity
                                          : FullMath.mulDiv(amount, FixedPoint96.Q96, liquidity)
                                  );
                              return uint256(sqrtPX96).add(quotient).toUint160();
                          } else {
                              uint256 quotient =
                                  (
                                      amount <= type(uint160).max
                                          ? UnsafeMath.divRoundingUp(amount << FixedPoint96.RESOLUTION, liquidity)
                                          : FullMath.mulDivRoundingUp(amount, FixedPoint96.Q96, liquidity)
                                  );
                              require(sqrtPX96 > quotient);
                              // always fits 160 bits
                              return uint160(sqrtPX96 - quotient);
                          }
                      }
                      /// @notice Gets the next sqrt price given an input amount of token0 or token1
                      /// @dev Throws if price or liquidity are 0, or if the next price is out of bounds
                      /// @param sqrtPX96 The starting price, i.e., before accounting for the input amount
                      /// @param liquidity The amount of usable liquidity
                      /// @param amountIn How much of token0, or token1, is being swapped in
                      /// @param zeroForOne Whether the amount in is token0 or token1
                      /// @return sqrtQX96 The price after adding the input amount to token0 or token1
                      function getNextSqrtPriceFromInput(
                          uint160 sqrtPX96,
                          uint128 liquidity,
                          uint256 amountIn,
                          bool zeroForOne
                      ) internal pure returns (uint160 sqrtQX96) {
                          require(sqrtPX96 > 0);
                          require(liquidity > 0);
                          // round to make sure that we don't pass the target price
                          return
                              zeroForOne
                                  ? getNextSqrtPriceFromAmount0RoundingUp(sqrtPX96, liquidity, amountIn, true)
                                  : getNextSqrtPriceFromAmount1RoundingDown(sqrtPX96, liquidity, amountIn, true);
                      }
                      /// @notice Gets the next sqrt price given an output amount of token0 or token1
                      /// @dev Throws if price or liquidity are 0 or the next price is out of bounds
                      /// @param sqrtPX96 The starting price before accounting for the output amount
                      /// @param liquidity The amount of usable liquidity
                      /// @param amountOut How much of token0, or token1, is being swapped out
                      /// @param zeroForOne Whether the amount out is token0 or token1
                      /// @return sqrtQX96 The price after removing the output amount of token0 or token1
                      function getNextSqrtPriceFromOutput(
                          uint160 sqrtPX96,
                          uint128 liquidity,
                          uint256 amountOut,
                          bool zeroForOne
                      ) internal pure returns (uint160 sqrtQX96) {
                          require(sqrtPX96 > 0);
                          require(liquidity > 0);
                          // round to make sure that we pass the target price
                          return
                              zeroForOne
                                  ? getNextSqrtPriceFromAmount1RoundingDown(sqrtPX96, liquidity, amountOut, false)
                                  : getNextSqrtPriceFromAmount0RoundingUp(sqrtPX96, liquidity, amountOut, false);
                      }
                      /// @notice Gets the amount0 delta between two prices
                      /// @dev Calculates liquidity / sqrt(lower) - liquidity / sqrt(upper),
                      /// i.e. liquidity * (sqrt(upper) - sqrt(lower)) / (sqrt(upper) * sqrt(lower))
                      /// @param sqrtRatioAX96 A sqrt price
                      /// @param sqrtRatioBX96 Another sqrt price
                      /// @param liquidity The amount of usable liquidity
                      /// @param roundUp Whether to round the amount up or down
                      /// @return amount0 Amount of token0 required to cover a position of size liquidity between the two passed prices
                      function getAmount0Delta(
                          uint160 sqrtRatioAX96,
                          uint160 sqrtRatioBX96,
                          uint128 liquidity,
                          bool roundUp
                      ) internal pure returns (uint256 amount0) {
                          if (sqrtRatioAX96 > sqrtRatioBX96) (sqrtRatioAX96, sqrtRatioBX96) = (sqrtRatioBX96, sqrtRatioAX96);
                          uint256 numerator1 = uint256(liquidity) << FixedPoint96.RESOLUTION;
                          uint256 numerator2 = sqrtRatioBX96 - sqrtRatioAX96;
                          require(sqrtRatioAX96 > 0);
                          return
                              roundUp
                                  ? UnsafeMath.divRoundingUp(
                                      FullMath.mulDivRoundingUp(numerator1, numerator2, sqrtRatioBX96),
                                      sqrtRatioAX96
                                  )
                                  : FullMath.mulDiv(numerator1, numerator2, sqrtRatioBX96) / sqrtRatioAX96;
                      }
                      /// @notice Gets the amount1 delta between two prices
                      /// @dev Calculates liquidity * (sqrt(upper) - sqrt(lower))
                      /// @param sqrtRatioAX96 A sqrt price
                      /// @param sqrtRatioBX96 Another sqrt price
                      /// @param liquidity The amount of usable liquidity
                      /// @param roundUp Whether to round the amount up, or down
                      /// @return amount1 Amount of token1 required to cover a position of size liquidity between the two passed prices
                      function getAmount1Delta(
                          uint160 sqrtRatioAX96,
                          uint160 sqrtRatioBX96,
                          uint128 liquidity,
                          bool roundUp
                      ) internal pure returns (uint256 amount1) {
                          if (sqrtRatioAX96 > sqrtRatioBX96) (sqrtRatioAX96, sqrtRatioBX96) = (sqrtRatioBX96, sqrtRatioAX96);
                          return
                              roundUp
                                  ? FullMath.mulDivRoundingUp(liquidity, sqrtRatioBX96 - sqrtRatioAX96, FixedPoint96.Q96)
                                  : FullMath.mulDiv(liquidity, sqrtRatioBX96 - sqrtRatioAX96, FixedPoint96.Q96);
                      }
                      /// @notice Helper that gets signed token0 delta
                      /// @param sqrtRatioAX96 A sqrt price
                      /// @param sqrtRatioBX96 Another sqrt price
                      /// @param liquidity The change in liquidity for which to compute the amount0 delta
                      /// @return amount0 Amount of token0 corresponding to the passed liquidityDelta between the two prices
                      function getAmount0Delta(
                          uint160 sqrtRatioAX96,
                          uint160 sqrtRatioBX96,
                          int128 liquidity
                      ) internal pure returns (int256 amount0) {
                          return
                              liquidity < 0
                                  ? -getAmount0Delta(sqrtRatioAX96, sqrtRatioBX96, uint128(-liquidity), false).toInt256()
                                  : getAmount0Delta(sqrtRatioAX96, sqrtRatioBX96, uint128(liquidity), true).toInt256();
                      }
                      /// @notice Helper that gets signed token1 delta
                      /// @param sqrtRatioAX96 A sqrt price
                      /// @param sqrtRatioBX96 Another sqrt price
                      /// @param liquidity The change in liquidity for which to compute the amount1 delta
                      /// @return amount1 Amount of token1 corresponding to the passed liquidityDelta between the two prices
                      function getAmount1Delta(
                          uint160 sqrtRatioAX96,
                          uint160 sqrtRatioBX96,
                          int128 liquidity
                      ) internal pure returns (int256 amount1) {
                          return
                              liquidity < 0
                                  ? -getAmount1Delta(sqrtRatioAX96, sqrtRatioBX96, uint128(-liquidity), false).toInt256()
                                  : getAmount1Delta(sqrtRatioAX96, sqrtRatioBX96, uint128(liquidity), true).toInt256();
                      }
                  }
                  // SPDX-License-Identifier: BUSL-1.1
                  pragma solidity >=0.5.0;
                  import './FullMath.sol';
                  import './SqrtPriceMath.sol';
                  /// @title Computes the result of a swap within ticks
                  /// @notice Contains methods for computing the result of a swap within a single tick price range, i.e., a single tick.
                  library SwapMath {
                      /// @notice Computes the result of swapping some amount in, or amount out, given the parameters of the swap
                      /// @dev The fee, plus the amount in, will never exceed the amount remaining if the swap's `amountSpecified` is positive
                      /// @param sqrtRatioCurrentX96 The current sqrt price of the pool
                      /// @param sqrtRatioTargetX96 The price that cannot be exceeded, from which the direction of the swap is inferred
                      /// @param liquidity The usable liquidity
                      /// @param amountRemaining How much input or output amount is remaining to be swapped in/out
                      /// @param feePips The fee taken from the input amount, expressed in hundredths of a bip
                      /// @return sqrtRatioNextX96 The price after swapping the amount in/out, not to exceed the price target
                      /// @return amountIn The amount to be swapped in, of either token0 or token1, based on the direction of the swap
                      /// @return amountOut The amount to be received, of either token0 or token1, based on the direction of the swap
                      /// @return feeAmount The amount of input that will be taken as a fee
                      function computeSwapStep(
                          uint160 sqrtRatioCurrentX96,
                          uint160 sqrtRatioTargetX96,
                          uint128 liquidity,
                          int256 amountRemaining,
                          uint24 feePips
                      )
                          internal
                          pure
                          returns (
                              uint160 sqrtRatioNextX96,
                              uint256 amountIn,
                              uint256 amountOut,
                              uint256 feeAmount
                          )
                      {
                          bool zeroForOne = sqrtRatioCurrentX96 >= sqrtRatioTargetX96;
                          bool exactIn = amountRemaining >= 0;
                          if (exactIn) {
                              uint256 amountRemainingLessFee = FullMath.mulDiv(uint256(amountRemaining), 1e6 - feePips, 1e6);
                              amountIn = zeroForOne
                                  ? SqrtPriceMath.getAmount0Delta(sqrtRatioTargetX96, sqrtRatioCurrentX96, liquidity, true)
                                  : SqrtPriceMath.getAmount1Delta(sqrtRatioCurrentX96, sqrtRatioTargetX96, liquidity, true);
                              if (amountRemainingLessFee >= amountIn) sqrtRatioNextX96 = sqrtRatioTargetX96;
                              else
                                  sqrtRatioNextX96 = SqrtPriceMath.getNextSqrtPriceFromInput(
                                      sqrtRatioCurrentX96,
                                      liquidity,
                                      amountRemainingLessFee,
                                      zeroForOne
                                  );
                          } else {
                              amountOut = zeroForOne
                                  ? SqrtPriceMath.getAmount1Delta(sqrtRatioTargetX96, sqrtRatioCurrentX96, liquidity, false)
                                  : SqrtPriceMath.getAmount0Delta(sqrtRatioCurrentX96, sqrtRatioTargetX96, liquidity, false);
                              if (uint256(-amountRemaining) >= amountOut) sqrtRatioNextX96 = sqrtRatioTargetX96;
                              else
                                  sqrtRatioNextX96 = SqrtPriceMath.getNextSqrtPriceFromOutput(
                                      sqrtRatioCurrentX96,
                                      liquidity,
                                      uint256(-amountRemaining),
                                      zeroForOne
                                  );
                          }
                          bool max = sqrtRatioTargetX96 == sqrtRatioNextX96;
                          // get the input/output amounts
                          if (zeroForOne) {
                              amountIn = max && exactIn
                                  ? amountIn
                                  : SqrtPriceMath.getAmount0Delta(sqrtRatioNextX96, sqrtRatioCurrentX96, liquidity, true);
                              amountOut = max && !exactIn
                                  ? amountOut
                                  : SqrtPriceMath.getAmount1Delta(sqrtRatioNextX96, sqrtRatioCurrentX96, liquidity, false);
                          } else {
                              amountIn = max && exactIn
                                  ? amountIn
                                  : SqrtPriceMath.getAmount1Delta(sqrtRatioCurrentX96, sqrtRatioNextX96, liquidity, true);
                              amountOut = max && !exactIn
                                  ? amountOut
                                  : SqrtPriceMath.getAmount0Delta(sqrtRatioCurrentX96, sqrtRatioNextX96, liquidity, false);
                          }
                          // cap the output amount to not exceed the remaining output amount
                          if (!exactIn && amountOut > uint256(-amountRemaining)) {
                              amountOut = uint256(-amountRemaining);
                          }
                          if (exactIn && sqrtRatioNextX96 != sqrtRatioTargetX96) {
                              // we didn't reach the target, so take the remainder of the maximum input as fee
                              feeAmount = uint256(amountRemaining) - amountIn;
                          } else {
                              feeAmount = FullMath.mulDivRoundingUp(amountIn, feePips, 1e6 - feePips);
                          }
                      }
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.5.0;
                  /// @title An interface for a contract that is capable of deploying Uniswap V3 Pools
                  /// @notice A contract that constructs a pool must implement this to pass arguments to the pool
                  /// @dev This is used to avoid having constructor arguments in the pool contract, which results in the init code hash
                  /// of the pool being constant allowing the CREATE2 address of the pool to be cheaply computed on-chain
                  interface IUniswapV3PoolDeployer {
                      /// @notice Get the parameters to be used in constructing the pool, set transiently during pool creation.
                      /// @dev Called by the pool constructor to fetch the parameters of the pool
                      /// Returns factory The factory address
                      /// Returns token0 The first token of the pool by address sort order
                      /// Returns token1 The second token of the pool by address sort order
                      /// Returns fee The fee collected upon every swap in the pool, denominated in hundredths of a bip
                      /// Returns tickSpacing The minimum number of ticks between initialized ticks
                      function parameters()
                          external
                          view
                          returns (
                              address factory,
                              address token0,
                              address token1,
                              uint24 fee,
                              int24 tickSpacing
                          );
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.5.0;
                  /// @title The interface for the Uniswap V3 Factory
                  /// @notice The Uniswap V3 Factory facilitates creation of Uniswap V3 pools and control over the protocol fees
                  interface IUniswapV3Factory {
                      /// @notice Emitted when the owner of the factory is changed
                      /// @param oldOwner The owner before the owner was changed
                      /// @param newOwner The owner after the owner was changed
                      event OwnerChanged(address indexed oldOwner, address indexed newOwner);
                      /// @notice Emitted when a pool is created
                      /// @param token0 The first token of the pool by address sort order
                      /// @param token1 The second token of the pool by address sort order
                      /// @param fee The fee collected upon every swap in the pool, denominated in hundredths of a bip
                      /// @param tickSpacing The minimum number of ticks between initialized ticks
                      /// @param pool The address of the created pool
                      event PoolCreated(
                          address indexed token0,
                          address indexed token1,
                          uint24 indexed fee,
                          int24 tickSpacing,
                          address pool
                      );
                      /// @notice Emitted when a new fee amount is enabled for pool creation via the factory
                      /// @param fee The enabled fee, denominated in hundredths of a bip
                      /// @param tickSpacing The minimum number of ticks between initialized ticks for pools created with the given fee
                      event FeeAmountEnabled(uint24 indexed fee, int24 indexed tickSpacing);
                      /// @notice Returns the current owner of the factory
                      /// @dev Can be changed by the current owner via setOwner
                      /// @return The address of the factory owner
                      function owner() external view returns (address);
                      /// @notice Returns the tick spacing for a given fee amount, if enabled, or 0 if not enabled
                      /// @dev A fee amount can never be removed, so this value should be hard coded or cached in the calling context
                      /// @param fee The enabled fee, denominated in hundredths of a bip. Returns 0 in case of unenabled fee
                      /// @return The tick spacing
                      function feeAmountTickSpacing(uint24 fee) external view returns (int24);
                      /// @notice Returns the pool address for a given pair of tokens and a fee, or address 0 if it does not exist
                      /// @dev tokenA and tokenB may be passed in either token0/token1 or token1/token0 order
                      /// @param tokenA The contract address of either token0 or token1
                      /// @param tokenB The contract address of the other token
                      /// @param fee The fee collected upon every swap in the pool, denominated in hundredths of a bip
                      /// @return pool The pool address
                      function getPool(
                          address tokenA,
                          address tokenB,
                          uint24 fee
                      ) external view returns (address pool);
                      /// @notice Creates a pool for the given two tokens and fee
                      /// @param tokenA One of the two tokens in the desired pool
                      /// @param tokenB The other of the two tokens in the desired pool
                      /// @param fee The desired fee for the pool
                      /// @dev tokenA and tokenB may be passed in either order: token0/token1 or token1/token0. tickSpacing is retrieved
                      /// from the fee. The call will revert if the pool already exists, the fee is invalid, or the token arguments
                      /// are invalid.
                      /// @return pool The address of the newly created pool
                      function createPool(
                          address tokenA,
                          address tokenB,
                          uint24 fee
                      ) external returns (address pool);
                      /// @notice Updates the owner of the factory
                      /// @dev Must be called by the current owner
                      /// @param _owner The new owner of the factory
                      function setOwner(address _owner) external;
                      /// @notice Enables a fee amount with the given tickSpacing
                      /// @dev Fee amounts may never be removed once enabled
                      /// @param fee The fee amount to enable, denominated in hundredths of a bip (i.e. 1e-6)
                      /// @param tickSpacing The spacing between ticks to be enforced for all pools created with the given fee amount
                      function enableFeeAmount(uint24 fee, int24 tickSpacing) external;
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.5.0;
                  /// @title Minimal ERC20 interface for Uniswap
                  /// @notice Contains a subset of the full ERC20 interface that is used in Uniswap V3
                  interface IERC20Minimal {
                      /// @notice Returns the balance of a token
                      /// @param account The account for which to look up the number of tokens it has, i.e. its balance
                      /// @return The number of tokens held by the account
                      function balanceOf(address account) external view returns (uint256);
                      /// @notice Transfers the amount of token from the `msg.sender` to the recipient
                      /// @param recipient The account that will receive the amount transferred
                      /// @param amount The number of tokens to send from the sender to the recipient
                      /// @return Returns true for a successful transfer, false for an unsuccessful transfer
                      function transfer(address recipient, uint256 amount) external returns (bool);
                      /// @notice Returns the current allowance given to a spender by an owner
                      /// @param owner The account of the token owner
                      /// @param spender The account of the token spender
                      /// @return The current allowance granted by `owner` to `spender`
                      function allowance(address owner, address spender) external view returns (uint256);
                      /// @notice Sets the allowance of a spender from the `msg.sender` to the value `amount`
                      /// @param spender The account which will be allowed to spend a given amount of the owners tokens
                      /// @param amount The amount of tokens allowed to be used by `spender`
                      /// @return Returns true for a successful approval, false for unsuccessful
                      function approve(address spender, uint256 amount) external returns (bool);
                      /// @notice Transfers `amount` tokens from `sender` to `recipient` up to the allowance given to the `msg.sender`
                      /// @param sender The account from which the transfer will be initiated
                      /// @param recipient The recipient of the transfer
                      /// @param amount The amount of the transfer
                      /// @return Returns true for a successful transfer, false for unsuccessful
                      function transferFrom(
                          address sender,
                          address recipient,
                          uint256 amount
                      ) external returns (bool);
                      /// @notice Event emitted when tokens are transferred from one address to another, either via `#transfer` or `#transferFrom`.
                      /// @param from The account from which the tokens were sent, i.e. the balance decreased
                      /// @param to The account to which the tokens were sent, i.e. the balance increased
                      /// @param value The amount of tokens that were transferred
                      event Transfer(address indexed from, address indexed to, uint256 value);
                      /// @notice Event emitted when the approval amount for the spender of a given owner's tokens changes.
                      /// @param owner The account that approved spending of its tokens
                      /// @param spender The account for which the spending allowance was modified
                      /// @param value The new allowance from the owner to the spender
                      event Approval(address indexed owner, address indexed spender, uint256 value);
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.5.0;
                  /// @title Callback for IUniswapV3PoolActions#mint
                  /// @notice Any contract that calls IUniswapV3PoolActions#mint must implement this interface
                  interface IUniswapV3MintCallback {
                      /// @notice Called to `msg.sender` after minting liquidity to a position from IUniswapV3Pool#mint.
                      /// @dev In the implementation you must pay the pool tokens owed for the minted liquidity.
                      /// The caller of this method must be checked to be a UniswapV3Pool deployed by the canonical UniswapV3Factory.
                      /// @param amount0Owed The amount of token0 due to the pool for the minted liquidity
                      /// @param amount1Owed The amount of token1 due to the pool for the minted liquidity
                      /// @param data Any data passed through by the caller via the IUniswapV3PoolActions#mint call
                      function uniswapV3MintCallback(
                          uint256 amount0Owed,
                          uint256 amount1Owed,
                          bytes calldata data
                      ) external;
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.5.0;
                  /// @title Callback for IUniswapV3PoolActions#swap
                  /// @notice Any contract that calls IUniswapV3PoolActions#swap must implement this interface
                  interface IUniswapV3SwapCallback {
                      /// @notice Called to `msg.sender` after executing a swap via IUniswapV3Pool#swap.
                      /// @dev In the implementation you must pay the pool tokens owed for the swap.
                      /// The caller of this method must be checked to be a UniswapV3Pool deployed by the canonical UniswapV3Factory.
                      /// amount0Delta and amount1Delta can both be 0 if no tokens were swapped.
                      /// @param amount0Delta The amount of token0 that was sent (negative) or must be received (positive) by the pool by
                      /// the end of the swap. If positive, the callback must send that amount of token0 to the pool.
                      /// @param amount1Delta The amount of token1 that was sent (negative) or must be received (positive) by the pool by
                      /// the end of the swap. If positive, the callback must send that amount of token1 to the pool.
                      /// @param data Any data passed through by the caller via the IUniswapV3PoolActions#swap call
                      function uniswapV3SwapCallback(
                          int256 amount0Delta,
                          int256 amount1Delta,
                          bytes calldata data
                      ) external;
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.5.0;
                  /// @title Callback for IUniswapV3PoolActions#flash
                  /// @notice Any contract that calls IUniswapV3PoolActions#flash must implement this interface
                  interface IUniswapV3FlashCallback {
                      /// @notice Called to `msg.sender` after transferring to the recipient from IUniswapV3Pool#flash.
                      /// @dev In the implementation you must repay the pool the tokens sent by flash plus the computed fee amounts.
                      /// The caller of this method must be checked to be a UniswapV3Pool deployed by the canonical UniswapV3Factory.
                      /// @param fee0 The fee amount in token0 due to the pool by the end of the flash
                      /// @param fee1 The fee amount in token1 due to the pool by the end of the flash
                      /// @param data Any data passed through by the caller via the IUniswapV3PoolActions#flash call
                      function uniswapV3FlashCallback(
                          uint256 fee0,
                          uint256 fee1,
                          bytes calldata data
                      ) external;
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.5.0;
                  /// @title Pool state that never changes
                  /// @notice These parameters are fixed for a pool forever, i.e., the methods will always return the same values
                  interface IUniswapV3PoolImmutables {
                      /// @notice The contract that deployed the pool, which must adhere to the IUniswapV3Factory interface
                      /// @return The contract address
                      function factory() external view returns (address);
                      /// @notice The first of the two tokens of the pool, sorted by address
                      /// @return The token contract address
                      function token0() external view returns (address);
                      /// @notice The second of the two tokens of the pool, sorted by address
                      /// @return The token contract address
                      function token1() external view returns (address);
                      /// @notice The pool's fee in hundredths of a bip, i.e. 1e-6
                      /// @return The fee
                      function fee() external view returns (uint24);
                      /// @notice The pool tick spacing
                      /// @dev Ticks can only be used at multiples of this value, minimum of 1 and always positive
                      /// e.g.: a tickSpacing of 3 means ticks can be initialized every 3rd tick, i.e., ..., -6, -3, 0, 3, 6, ...
                      /// This value is an int24 to avoid casting even though it is always positive.
                      /// @return The tick spacing
                      function tickSpacing() external view returns (int24);
                      /// @notice The maximum amount of position liquidity that can use any tick in the range
                      /// @dev This parameter is enforced per tick to prevent liquidity from overflowing a uint128 at any point, and
                      /// also prevents out-of-range liquidity from being used to prevent adding in-range liquidity to a pool
                      /// @return The max amount of liquidity per tick
                      function maxLiquidityPerTick() external view returns (uint128);
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.5.0;
                  /// @title Pool state that can change
                  /// @notice These methods compose the pool's state, and can change with any frequency including multiple times
                  /// per transaction
                  interface IUniswapV3PoolState {
                      /// @notice The 0th storage slot in the pool stores many values, and is exposed as a single method to save gas
                      /// when accessed externally.
                      /// @return sqrtPriceX96 The current price of the pool as a sqrt(token1/token0) Q64.96 value
                      /// tick The current tick of the pool, i.e. according to the last tick transition that was run.
                      /// This value may not always be equal to SqrtTickMath.getTickAtSqrtRatio(sqrtPriceX96) if the price is on a tick
                      /// boundary.
                      /// observationIndex The index of the last oracle observation that was written,
                      /// observationCardinality The current maximum number of observations stored in the pool,
                      /// observationCardinalityNext The next maximum number of observations, to be updated when the observation.
                      /// feeProtocol The protocol fee for both tokens of the pool.
                      /// Encoded as two 4 bit values, where the protocol fee of token1 is shifted 4 bits and the protocol fee of token0
                      /// is the lower 4 bits. Used as the denominator of a fraction of the swap fee, e.g. 4 means 1/4th of the swap fee.
                      /// unlocked Whether the pool is currently locked to reentrancy
                      function slot0()
                          external
                          view
                          returns (
                              uint160 sqrtPriceX96,
                              int24 tick,
                              uint16 observationIndex,
                              uint16 observationCardinality,
                              uint16 observationCardinalityNext,
                              uint8 feeProtocol,
                              bool unlocked
                          );
                      /// @notice The fee growth as a Q128.128 fees of token0 collected per unit of liquidity for the entire life of the pool
                      /// @dev This value can overflow the uint256
                      function feeGrowthGlobal0X128() external view returns (uint256);
                      /// @notice The fee growth as a Q128.128 fees of token1 collected per unit of liquidity for the entire life of the pool
                      /// @dev This value can overflow the uint256
                      function feeGrowthGlobal1X128() external view returns (uint256);
                      /// @notice The amounts of token0 and token1 that are owed to the protocol
                      /// @dev Protocol fees will never exceed uint128 max in either token
                      function protocolFees() external view returns (uint128 token0, uint128 token1);
                      /// @notice The currently in range liquidity available to the pool
                      /// @dev This value has no relationship to the total liquidity across all ticks
                      function liquidity() external view returns (uint128);
                      /// @notice Look up information about a specific tick in the pool
                      /// @param tick The tick to look up
                      /// @return liquidityGross the total amount of position liquidity that uses the pool either as tick lower or
                      /// tick upper,
                      /// liquidityNet how much liquidity changes when the pool price crosses the tick,
                      /// feeGrowthOutside0X128 the fee growth on the other side of the tick from the current tick in token0,
                      /// feeGrowthOutside1X128 the fee growth on the other side of the tick from the current tick in token1,
                      /// tickCumulativeOutside the cumulative tick value on the other side of the tick from the current tick
                      /// secondsPerLiquidityOutsideX128 the seconds spent per liquidity on the other side of the tick from the current tick,
                      /// secondsOutside the seconds spent on the other side of the tick from the current tick,
                      /// initialized Set to true if the tick is initialized, i.e. liquidityGross is greater than 0, otherwise equal to false.
                      /// Outside values can only be used if the tick is initialized, i.e. if liquidityGross is greater than 0.
                      /// In addition, these values are only relative and must be used only in comparison to previous snapshots for
                      /// a specific position.
                      function ticks(int24 tick)
                          external
                          view
                          returns (
                              uint128 liquidityGross,
                              int128 liquidityNet,
                              uint256 feeGrowthOutside0X128,
                              uint256 feeGrowthOutside1X128,
                              int56 tickCumulativeOutside,
                              uint160 secondsPerLiquidityOutsideX128,
                              uint32 secondsOutside,
                              bool initialized
                          );
                      /// @notice Returns 256 packed tick initialized boolean values. See TickBitmap for more information
                      function tickBitmap(int16 wordPosition) external view returns (uint256);
                      /// @notice Returns the information about a position by the position's key
                      /// @param key The position's key is a hash of a preimage composed by the owner, tickLower and tickUpper
                      /// @return _liquidity The amount of liquidity in the position,
                      /// Returns feeGrowthInside0LastX128 fee growth of token0 inside the tick range as of the last mint/burn/poke,
                      /// Returns feeGrowthInside1LastX128 fee growth of token1 inside the tick range as of the last mint/burn/poke,
                      /// Returns tokensOwed0 the computed amount of token0 owed to the position as of the last mint/burn/poke,
                      /// Returns tokensOwed1 the computed amount of token1 owed to the position as of the last mint/burn/poke
                      function positions(bytes32 key)
                          external
                          view
                          returns (
                              uint128 _liquidity,
                              uint256 feeGrowthInside0LastX128,
                              uint256 feeGrowthInside1LastX128,
                              uint128 tokensOwed0,
                              uint128 tokensOwed1
                          );
                      /// @notice Returns data about a specific observation index
                      /// @param index The element of the observations array to fetch
                      /// @dev You most likely want to use #observe() instead of this method to get an observation as of some amount of time
                      /// ago, rather than at a specific index in the array.
                      /// @return blockTimestamp The timestamp of the observation,
                      /// Returns tickCumulative the tick multiplied by seconds elapsed for the life of the pool as of the observation timestamp,
                      /// Returns secondsPerLiquidityCumulativeX128 the seconds per in range liquidity for the life of the pool as of the observation timestamp,
                      /// Returns initialized whether the observation has been initialized and the values are safe to use
                      function observations(uint256 index)
                          external
                          view
                          returns (
                              uint32 blockTimestamp,
                              int56 tickCumulative,
                              uint160 secondsPerLiquidityCumulativeX128,
                              bool initialized
                          );
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.5.0;
                  /// @title Pool state that is not stored
                  /// @notice Contains view functions to provide information about the pool that is computed rather than stored on the
                  /// blockchain. The functions here may have variable gas costs.
                  interface IUniswapV3PoolDerivedState {
                      /// @notice Returns the cumulative tick and liquidity as of each timestamp `secondsAgo` from the current block timestamp
                      /// @dev To get a time weighted average tick or liquidity-in-range, you must call this with two values, one representing
                      /// the beginning of the period and another for the end of the period. E.g., to get the last hour time-weighted average tick,
                      /// you must call it with secondsAgos = [3600, 0].
                      /// @dev The time weighted average tick represents the geometric time weighted average price of the pool, in
                      /// log base sqrt(1.0001) of token1 / token0. The TickMath library can be used to go from a tick value to a ratio.
                      /// @param secondsAgos From how long ago each cumulative tick and liquidity value should be returned
                      /// @return tickCumulatives Cumulative tick values as of each `secondsAgos` from the current block timestamp
                      /// @return secondsPerLiquidityCumulativeX128s Cumulative seconds per liquidity-in-range value as of each `secondsAgos` from the current block
                      /// timestamp
                      function observe(uint32[] calldata secondsAgos)
                          external
                          view
                          returns (int56[] memory tickCumulatives, uint160[] memory secondsPerLiquidityCumulativeX128s);
                      /// @notice Returns a snapshot of the tick cumulative, seconds per liquidity and seconds inside a tick range
                      /// @dev Snapshots must only be compared to other snapshots, taken over a period for which a position existed.
                      /// I.e., snapshots cannot be compared if a position is not held for the entire period between when the first
                      /// snapshot is taken and the second snapshot is taken.
                      /// @param tickLower The lower tick of the range
                      /// @param tickUpper The upper tick of the range
                      /// @return tickCumulativeInside The snapshot of the tick accumulator for the range
                      /// @return secondsPerLiquidityInsideX128 The snapshot of seconds per liquidity for the range
                      /// @return secondsInside The snapshot of seconds per liquidity for the range
                      function snapshotCumulativesInside(int24 tickLower, int24 tickUpper)
                          external
                          view
                          returns (
                              int56 tickCumulativeInside,
                              uint160 secondsPerLiquidityInsideX128,
                              uint32 secondsInside
                          );
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.5.0;
                  /// @title Permissionless pool actions
                  /// @notice Contains pool methods that can be called by anyone
                  interface IUniswapV3PoolActions {
                      /// @notice Sets the initial price for the pool
                      /// @dev Price is represented as a sqrt(amountToken1/amountToken0) Q64.96 value
                      /// @param sqrtPriceX96 the initial sqrt price of the pool as a Q64.96
                      function initialize(uint160 sqrtPriceX96) external;
                      /// @notice Adds liquidity for the given recipient/tickLower/tickUpper position
                      /// @dev The caller of this method receives a callback in the form of IUniswapV3MintCallback#uniswapV3MintCallback
                      /// in which they must pay any token0 or token1 owed for the liquidity. The amount of token0/token1 due depends
                      /// on tickLower, tickUpper, the amount of liquidity, and the current price.
                      /// @param recipient The address for which the liquidity will be created
                      /// @param tickLower The lower tick of the position in which to add liquidity
                      /// @param tickUpper The upper tick of the position in which to add liquidity
                      /// @param amount The amount of liquidity to mint
                      /// @param data Any data that should be passed through to the callback
                      /// @return amount0 The amount of token0 that was paid to mint the given amount of liquidity. Matches the value in the callback
                      /// @return amount1 The amount of token1 that was paid to mint the given amount of liquidity. Matches the value in the callback
                      function mint(
                          address recipient,
                          int24 tickLower,
                          int24 tickUpper,
                          uint128 amount,
                          bytes calldata data
                      ) external returns (uint256 amount0, uint256 amount1);
                      /// @notice Collects tokens owed to a position
                      /// @dev Does not recompute fees earned, which must be done either via mint or burn of any amount of liquidity.
                      /// Collect must be called by the position owner. To withdraw only token0 or only token1, amount0Requested or
                      /// amount1Requested may be set to zero. To withdraw all tokens owed, caller may pass any value greater than the
                      /// actual tokens owed, e.g. type(uint128).max. Tokens owed may be from accumulated swap fees or burned liquidity.
                      /// @param recipient The address which should receive the fees collected
                      /// @param tickLower The lower tick of the position for which to collect fees
                      /// @param tickUpper The upper tick of the position for which to collect fees
                      /// @param amount0Requested How much token0 should be withdrawn from the fees owed
                      /// @param amount1Requested How much token1 should be withdrawn from the fees owed
                      /// @return amount0 The amount of fees collected in token0
                      /// @return amount1 The amount of fees collected in token1
                      function collect(
                          address recipient,
                          int24 tickLower,
                          int24 tickUpper,
                          uint128 amount0Requested,
                          uint128 amount1Requested
                      ) external returns (uint128 amount0, uint128 amount1);
                      /// @notice Burn liquidity from the sender and account tokens owed for the liquidity to the position
                      /// @dev Can be used to trigger a recalculation of fees owed to a position by calling with an amount of 0
                      /// @dev Fees must be collected separately via a call to #collect
                      /// @param tickLower The lower tick of the position for which to burn liquidity
                      /// @param tickUpper The upper tick of the position for which to burn liquidity
                      /// @param amount How much liquidity to burn
                      /// @return amount0 The amount of token0 sent to the recipient
                      /// @return amount1 The amount of token1 sent to the recipient
                      function burn(
                          int24 tickLower,
                          int24 tickUpper,
                          uint128 amount
                      ) external returns (uint256 amount0, uint256 amount1);
                      /// @notice Swap token0 for token1, or token1 for token0
                      /// @dev The caller of this method receives a callback in the form of IUniswapV3SwapCallback#uniswapV3SwapCallback
                      /// @param recipient The address to receive the output of the swap
                      /// @param zeroForOne The direction of the swap, true for token0 to token1, false for token1 to token0
                      /// @param amountSpecified The amount of the swap, which implicitly configures the swap as exact input (positive), or exact output (negative)
                      /// @param sqrtPriceLimitX96 The Q64.96 sqrt price limit. If zero for one, the price cannot be less than this
                      /// value after the swap. If one for zero, the price cannot be greater than this value after the swap
                      /// @param data Any data to be passed through to the callback
                      /// @return amount0 The delta of the balance of token0 of the pool, exact when negative, minimum when positive
                      /// @return amount1 The delta of the balance of token1 of the pool, exact when negative, minimum when positive
                      function swap(
                          address recipient,
                          bool zeroForOne,
                          int256 amountSpecified,
                          uint160 sqrtPriceLimitX96,
                          bytes calldata data
                      ) external returns (int256 amount0, int256 amount1);
                      /// @notice Receive token0 and/or token1 and pay it back, plus a fee, in the callback
                      /// @dev The caller of this method receives a callback in the form of IUniswapV3FlashCallback#uniswapV3FlashCallback
                      /// @dev Can be used to donate underlying tokens pro-rata to currently in-range liquidity providers by calling
                      /// with 0 amount{0,1} and sending the donation amount(s) from the callback
                      /// @param recipient The address which will receive the token0 and token1 amounts
                      /// @param amount0 The amount of token0 to send
                      /// @param amount1 The amount of token1 to send
                      /// @param data Any data to be passed through to the callback
                      function flash(
                          address recipient,
                          uint256 amount0,
                          uint256 amount1,
                          bytes calldata data
                      ) external;
                      /// @notice Increase the maximum number of price and liquidity observations that this pool will store
                      /// @dev This method is no-op if the pool already has an observationCardinalityNext greater than or equal to
                      /// the input observationCardinalityNext.
                      /// @param observationCardinalityNext The desired minimum number of observations for the pool to store
                      function increaseObservationCardinalityNext(uint16 observationCardinalityNext) external;
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.5.0;
                  /// @title Permissioned pool actions
                  /// @notice Contains pool methods that may only be called by the factory owner
                  interface IUniswapV3PoolOwnerActions {
                      /// @notice Set the denominator of the protocol's % share of the fees
                      /// @param feeProtocol0 new protocol fee for token0 of the pool
                      /// @param feeProtocol1 new protocol fee for token1 of the pool
                      function setFeeProtocol(uint8 feeProtocol0, uint8 feeProtocol1) external;
                      /// @notice Collect the protocol fee accrued to the pool
                      /// @param recipient The address to which collected protocol fees should be sent
                      /// @param amount0Requested The maximum amount of token0 to send, can be 0 to collect fees in only token1
                      /// @param amount1Requested The maximum amount of token1 to send, can be 0 to collect fees in only token0
                      /// @return amount0 The protocol fee collected in token0
                      /// @return amount1 The protocol fee collected in token1
                      function collectProtocol(
                          address recipient,
                          uint128 amount0Requested,
                          uint128 amount1Requested
                      ) external returns (uint128 amount0, uint128 amount1);
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.5.0;
                  /// @title Events emitted by a pool
                  /// @notice Contains all events emitted by the pool
                  interface IUniswapV3PoolEvents {
                      /// @notice Emitted exactly once by a pool when #initialize is first called on the pool
                      /// @dev Mint/Burn/Swap cannot be emitted by the pool before Initialize
                      /// @param sqrtPriceX96 The initial sqrt price of the pool, as a Q64.96
                      /// @param tick The initial tick of the pool, i.e. log base 1.0001 of the starting price of the pool
                      event Initialize(uint160 sqrtPriceX96, int24 tick);
                      /// @notice Emitted when liquidity is minted for a given position
                      /// @param sender The address that minted the liquidity
                      /// @param owner The owner of the position and recipient of any minted liquidity
                      /// @param tickLower The lower tick of the position
                      /// @param tickUpper The upper tick of the position
                      /// @param amount The amount of liquidity minted to the position range
                      /// @param amount0 How much token0 was required for the minted liquidity
                      /// @param amount1 How much token1 was required for the minted liquidity
                      event Mint(
                          address sender,
                          address indexed owner,
                          int24 indexed tickLower,
                          int24 indexed tickUpper,
                          uint128 amount,
                          uint256 amount0,
                          uint256 amount1
                      );
                      /// @notice Emitted when fees are collected by the owner of a position
                      /// @dev Collect events may be emitted with zero amount0 and amount1 when the caller chooses not to collect fees
                      /// @param owner The owner of the position for which fees are collected
                      /// @param tickLower The lower tick of the position
                      /// @param tickUpper The upper tick of the position
                      /// @param amount0 The amount of token0 fees collected
                      /// @param amount1 The amount of token1 fees collected
                      event Collect(
                          address indexed owner,
                          address recipient,
                          int24 indexed tickLower,
                          int24 indexed tickUpper,
                          uint128 amount0,
                          uint128 amount1
                      );
                      /// @notice Emitted when a position's liquidity is removed
                      /// @dev Does not withdraw any fees earned by the liquidity position, which must be withdrawn via #collect
                      /// @param owner The owner of the position for which liquidity is removed
                      /// @param tickLower The lower tick of the position
                      /// @param tickUpper The upper tick of the position
                      /// @param amount The amount of liquidity to remove
                      /// @param amount0 The amount of token0 withdrawn
                      /// @param amount1 The amount of token1 withdrawn
                      event Burn(
                          address indexed owner,
                          int24 indexed tickLower,
                          int24 indexed tickUpper,
                          uint128 amount,
                          uint256 amount0,
                          uint256 amount1
                      );
                      /// @notice Emitted by the pool for any swaps between token0 and token1
                      /// @param sender The address that initiated the swap call, and that received the callback
                      /// @param recipient The address that received the output of the swap
                      /// @param amount0 The delta of the token0 balance of the pool
                      /// @param amount1 The delta of the token1 balance of the pool
                      /// @param sqrtPriceX96 The sqrt(price) of the pool after the swap, as a Q64.96
                      /// @param liquidity The liquidity of the pool after the swap
                      /// @param tick The log base 1.0001 of price of the pool after the swap
                      event Swap(
                          address indexed sender,
                          address indexed recipient,
                          int256 amount0,
                          int256 amount1,
                          uint160 sqrtPriceX96,
                          uint128 liquidity,
                          int24 tick
                      );
                      /// @notice Emitted by the pool for any flashes of token0/token1
                      /// @param sender The address that initiated the swap call, and that received the callback
                      /// @param recipient The address that received the tokens from flash
                      /// @param amount0 The amount of token0 that was flashed
                      /// @param amount1 The amount of token1 that was flashed
                      /// @param paid0 The amount of token0 paid for the flash, which can exceed the amount0 plus the fee
                      /// @param paid1 The amount of token1 paid for the flash, which can exceed the amount1 plus the fee
                      event Flash(
                          address indexed sender,
                          address indexed recipient,
                          uint256 amount0,
                          uint256 amount1,
                          uint256 paid0,
                          uint256 paid1
                      );
                      /// @notice Emitted by the pool for increases to the number of observations that can be stored
                      /// @dev observationCardinalityNext is not the observation cardinality until an observation is written at the index
                      /// just before a mint/swap/burn.
                      /// @param observationCardinalityNextOld The previous value of the next observation cardinality
                      /// @param observationCardinalityNextNew The updated value of the next observation cardinality
                      event IncreaseObservationCardinalityNext(
                          uint16 observationCardinalityNextOld,
                          uint16 observationCardinalityNextNew
                      );
                      /// @notice Emitted when the protocol fee is changed by the pool
                      /// @param feeProtocol0Old The previous value of the token0 protocol fee
                      /// @param feeProtocol1Old The previous value of the token1 protocol fee
                      /// @param feeProtocol0New The updated value of the token0 protocol fee
                      /// @param feeProtocol1New The updated value of the token1 protocol fee
                      event SetFeeProtocol(uint8 feeProtocol0Old, uint8 feeProtocol1Old, uint8 feeProtocol0New, uint8 feeProtocol1New);
                      /// @notice Emitted when the collected protocol fees are withdrawn by the factory owner
                      /// @param sender The address that collects the protocol fees
                      /// @param recipient The address that receives the collected protocol fees
                      /// @param amount0 The amount of token0 protocol fees that is withdrawn
                      /// @param amount0 The amount of token1 protocol fees that is withdrawn
                      event CollectProtocol(address indexed sender, address indexed recipient, uint128 amount0, uint128 amount1);
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.5.0;
                  /// @title BitMath
                  /// @dev This library provides functionality for computing bit properties of an unsigned integer
                  library BitMath {
                      /// @notice Returns the index of the most significant bit of the number,
                      ///     where the least significant bit is at index 0 and the most significant bit is at index 255
                      /// @dev The function satisfies the property:
                      ///     x >= 2**mostSignificantBit(x) and x < 2**(mostSignificantBit(x)+1)
                      /// @param x the value for which to compute the most significant bit, must be greater than 0
                      /// @return r the index of the most significant bit
                      function mostSignificantBit(uint256 x) internal pure returns (uint8 r) {
                          require(x > 0);
                          if (x >= 0x100000000000000000000000000000000) {
                              x >>= 128;
                              r += 128;
                          }
                          if (x >= 0x10000000000000000) {
                              x >>= 64;
                              r += 64;
                          }
                          if (x >= 0x100000000) {
                              x >>= 32;
                              r += 32;
                          }
                          if (x >= 0x10000) {
                              x >>= 16;
                              r += 16;
                          }
                          if (x >= 0x100) {
                              x >>= 8;
                              r += 8;
                          }
                          if (x >= 0x10) {
                              x >>= 4;
                              r += 4;
                          }
                          if (x >= 0x4) {
                              x >>= 2;
                              r += 2;
                          }
                          if (x >= 0x2) r += 1;
                      }
                      /// @notice Returns the index of the least significant bit of the number,
                      ///     where the least significant bit is at index 0 and the most significant bit is at index 255
                      /// @dev The function satisfies the property:
                      ///     (x & 2**leastSignificantBit(x)) != 0 and (x & (2**(leastSignificantBit(x)) - 1)) == 0)
                      /// @param x the value for which to compute the least significant bit, must be greater than 0
                      /// @return r the index of the least significant bit
                      function leastSignificantBit(uint256 x) internal pure returns (uint8 r) {
                          require(x > 0);
                          r = 255;
                          if (x & type(uint128).max > 0) {
                              r -= 128;
                          } else {
                              x >>= 128;
                          }
                          if (x & type(uint64).max > 0) {
                              r -= 64;
                          } else {
                              x >>= 64;
                          }
                          if (x & type(uint32).max > 0) {
                              r -= 32;
                          } else {
                              x >>= 32;
                          }
                          if (x & type(uint16).max > 0) {
                              r -= 16;
                          } else {
                              x >>= 16;
                          }
                          if (x & type(uint8).max > 0) {
                              r -= 8;
                          } else {
                              x >>= 8;
                          }
                          if (x & 0xf > 0) {
                              r -= 4;
                          } else {
                              x >>= 4;
                          }
                          if (x & 0x3 > 0) {
                              r -= 2;
                          } else {
                              x >>= 2;
                          }
                          if (x & 0x1 > 0) r -= 1;
                      }
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.5.0;
                  /// @title Math functions that do not check inputs or outputs
                  /// @notice Contains methods that perform common math functions but do not do any overflow or underflow checks
                  library UnsafeMath {
                      /// @notice Returns ceil(x / y)
                      /// @dev division by 0 has unspecified behavior, and must be checked externally
                      /// @param x The dividend
                      /// @param y The divisor
                      /// @return z The quotient, ceil(x / y)
                      function divRoundingUp(uint256 x, uint256 y) internal pure returns (uint256 z) {
                          assembly {
                              z := add(div(x, y), gt(mod(x, y), 0))
                          }
                      }
                  }
                  // SPDX-License-Identifier: GPL-2.0-or-later
                  pragma solidity >=0.4.0;
                  /// @title FixedPoint96
                  /// @notice A library for handling binary fixed point numbers, see https://en.wikipedia.org/wiki/Q_(number_format)
                  /// @dev Used in SqrtPriceMath.sol
                  library FixedPoint96 {
                      uint8 internal constant RESOLUTION = 96;
                      uint256 internal constant Q96 = 0x1000000000000000000000000;
                  }
                  

                  File 3 of 6: GhoToken
                  // SPDX-License-Identifier: MIT
                  pragma solidity ^0.8.0;
                  import {EnumerableSet} from '@openzeppelin/contracts/utils/structs/EnumerableSet.sol';
                  import {AccessControl} from '@openzeppelin/contracts/access/AccessControl.sol';
                  import {ERC20} from './ERC20.sol';
                  import {IGhoToken} from './interfaces/IGhoToken.sol';
                  /**
                   * @title GHO Token
                   * @author Aave
                   */
                  contract GhoToken is ERC20, AccessControl, IGhoToken {
                    using EnumerableSet for EnumerableSet.AddressSet;
                    mapping(address => Facilitator) internal _facilitators;
                    EnumerableSet.AddressSet internal _facilitatorsList;
                    /// @inheritdoc IGhoToken
                    bytes32 public constant FACILITATOR_MANAGER_ROLE = keccak256('FACILITATOR_MANAGER_ROLE');
                    /// @inheritdoc IGhoToken
                    bytes32 public constant BUCKET_MANAGER_ROLE = keccak256('BUCKET_MANAGER_ROLE');
                    /**
                     * @dev Constructor
                     * @param admin This is the initial holder of the default admin role
                     */
                    constructor(address admin) ERC20('Gho Token', 'GHO', 18) {
                      _setupRole(DEFAULT_ADMIN_ROLE, admin);
                    }
                    /// @inheritdoc IGhoToken
                    function mint(address account, uint256 amount) external {
                      require(amount > 0, 'INVALID_MINT_AMOUNT');
                      Facilitator storage f = _facilitators[msg.sender];
                      uint256 currentBucketLevel = f.bucketLevel;
                      uint256 newBucketLevel = currentBucketLevel + amount;
                      require(f.bucketCapacity >= newBucketLevel, 'FACILITATOR_BUCKET_CAPACITY_EXCEEDED');
                      f.bucketLevel = uint128(newBucketLevel);
                      _mint(account, amount);
                      emit FacilitatorBucketLevelUpdated(msg.sender, currentBucketLevel, newBucketLevel);
                    }
                    /// @inheritdoc IGhoToken
                    function burn(uint256 amount) external {
                      require(amount > 0, 'INVALID_BURN_AMOUNT');
                      Facilitator storage f = _facilitators[msg.sender];
                      uint256 currentBucketLevel = f.bucketLevel;
                      uint256 newBucketLevel = currentBucketLevel - amount;
                      f.bucketLevel = uint128(newBucketLevel);
                      _burn(msg.sender, amount);
                      emit FacilitatorBucketLevelUpdated(msg.sender, currentBucketLevel, newBucketLevel);
                    }
                    /// @inheritdoc IGhoToken
                    function addFacilitator(
                      address facilitatorAddress,
                      string calldata facilitatorLabel,
                      uint128 bucketCapacity
                    ) external onlyRole(FACILITATOR_MANAGER_ROLE) {
                      Facilitator storage facilitator = _facilitators[facilitatorAddress];
                      require(bytes(facilitator.label).length == 0, 'FACILITATOR_ALREADY_EXISTS');
                      require(bytes(facilitatorLabel).length > 0, 'INVALID_LABEL');
                      facilitator.label = facilitatorLabel;
                      facilitator.bucketCapacity = bucketCapacity;
                      _facilitatorsList.add(facilitatorAddress);
                      emit FacilitatorAdded(
                        facilitatorAddress,
                        keccak256(abi.encodePacked(facilitatorLabel)),
                        bucketCapacity
                      );
                    }
                    /// @inheritdoc IGhoToken
                    function removeFacilitator(
                      address facilitatorAddress
                    ) external onlyRole(FACILITATOR_MANAGER_ROLE) {
                      require(
                        bytes(_facilitators[facilitatorAddress].label).length > 0,
                        'FACILITATOR_DOES_NOT_EXIST'
                      );
                      require(
                        _facilitators[facilitatorAddress].bucketLevel == 0,
                        'FACILITATOR_BUCKET_LEVEL_NOT_ZERO'
                      );
                      delete _facilitators[facilitatorAddress];
                      _facilitatorsList.remove(facilitatorAddress);
                      emit FacilitatorRemoved(facilitatorAddress);
                    }
                    /// @inheritdoc IGhoToken
                    function setFacilitatorBucketCapacity(
                      address facilitator,
                      uint128 newCapacity
                    ) external onlyRole(BUCKET_MANAGER_ROLE) {
                      require(bytes(_facilitators[facilitator].label).length > 0, 'FACILITATOR_DOES_NOT_EXIST');
                      uint256 oldCapacity = _facilitators[facilitator].bucketCapacity;
                      _facilitators[facilitator].bucketCapacity = newCapacity;
                      emit FacilitatorBucketCapacityUpdated(facilitator, oldCapacity, newCapacity);
                    }
                    /// @inheritdoc IGhoToken
                    function getFacilitator(address facilitator) external view returns (Facilitator memory) {
                      return _facilitators[facilitator];
                    }
                    /// @inheritdoc IGhoToken
                    function getFacilitatorBucket(address facilitator) external view returns (uint256, uint256) {
                      return (_facilitators[facilitator].bucketCapacity, _facilitators[facilitator].bucketLevel);
                    }
                    /// @inheritdoc IGhoToken
                    function getFacilitatorsList() external view returns (address[] memory) {
                      return _facilitatorsList.values();
                    }
                  }
                  // SPDX-License-Identifier: MIT
                  // OpenZeppelin Contracts (last updated v4.8.0) (utils/structs/EnumerableSet.sol)
                  // This file was procedurally generated from scripts/generate/templates/EnumerableSet.js.
                  pragma solidity ^0.8.0;
                  /**
                   * @dev Library for managing
                   * https://en.wikipedia.org/wiki/Set_(abstract_data_type)[sets] of primitive
                   * types.
                   *
                   * Sets have the following properties:
                   *
                   * - Elements are added, removed, and checked for existence in constant time
                   * (O(1)).
                   * - Elements are enumerated in O(n). No guarantees are made on the ordering.
                   *
                   * ```
                   * contract Example {
                   *     // Add the library methods
                   *     using EnumerableSet for EnumerableSet.AddressSet;
                   *
                   *     // Declare a set state variable
                   *     EnumerableSet.AddressSet private mySet;
                   * }
                   * ```
                   *
                   * As of v3.3.0, sets of type `bytes32` (`Bytes32Set`), `address` (`AddressSet`)
                   * and `uint256` (`UintSet`) are supported.
                   *
                   * [WARNING]
                   * ====
                   * Trying to delete such a structure from storage will likely result in data corruption, rendering the structure
                   * unusable.
                   * See https://github.com/ethereum/solidity/pull/11843[ethereum/solidity#11843] for more info.
                   *
                   * In order to clean an EnumerableSet, you can either remove all elements one by one or create a fresh instance using an
                   * array of EnumerableSet.
                   * ====
                   */
                  library EnumerableSet {
                      // To implement this library for multiple types with as little code
                      // repetition as possible, we write it in terms of a generic Set type with
                      // bytes32 values.
                      // The Set implementation uses private functions, and user-facing
                      // implementations (such as AddressSet) are just wrappers around the
                      // underlying Set.
                      // This means that we can only create new EnumerableSets for types that fit
                      // in bytes32.
                      struct Set {
                          // Storage of set values
                          bytes32[] _values;
                          // Position of the value in the `values` array, plus 1 because index 0
                          // means a value is not in the set.
                          mapping(bytes32 => uint256) _indexes;
                      }
                      /**
                       * @dev Add a value to a set. O(1).
                       *
                       * Returns true if the value was added to the set, that is if it was not
                       * already present.
                       */
                      function _add(Set storage set, bytes32 value) private returns (bool) {
                          if (!_contains(set, value)) {
                              set._values.push(value);
                              // The value is stored at length-1, but we add 1 to all indexes
                              // and use 0 as a sentinel value
                              set._indexes[value] = set._values.length;
                              return true;
                          } else {
                              return false;
                          }
                      }
                      /**
                       * @dev Removes a value from a set. O(1).
                       *
                       * Returns true if the value was removed from the set, that is if it was
                       * present.
                       */
                      function _remove(Set storage set, bytes32 value) private returns (bool) {
                          // We read and store the value's index to prevent multiple reads from the same storage slot
                          uint256 valueIndex = set._indexes[value];
                          if (valueIndex != 0) {
                              // Equivalent to contains(set, value)
                              // To delete an element from the _values array in O(1), we swap the element to delete with the last one in
                              // the array, and then remove the last element (sometimes called as 'swap and pop').
                              // This modifies the order of the array, as noted in {at}.
                              uint256 toDeleteIndex = valueIndex - 1;
                              uint256 lastIndex = set._values.length - 1;
                              if (lastIndex != toDeleteIndex) {
                                  bytes32 lastValue = set._values[lastIndex];
                                  // Move the last value to the index where the value to delete is
                                  set._values[toDeleteIndex] = lastValue;
                                  // Update the index for the moved value
                                  set._indexes[lastValue] = valueIndex; // Replace lastValue's index to valueIndex
                              }
                              // Delete the slot where the moved value was stored
                              set._values.pop();
                              // Delete the index for the deleted slot
                              delete set._indexes[value];
                              return true;
                          } else {
                              return false;
                          }
                      }
                      /**
                       * @dev Returns true if the value is in the set. O(1).
                       */
                      function _contains(Set storage set, bytes32 value) private view returns (bool) {
                          return set._indexes[value] != 0;
                      }
                      /**
                       * @dev Returns the number of values on the set. O(1).
                       */
                      function _length(Set storage set) private view returns (uint256) {
                          return set._values.length;
                      }
                      /**
                       * @dev Returns the value stored at position `index` in the set. O(1).
                       *
                       * Note that there are no guarantees on the ordering of values inside the
                       * array, and it may change when more values are added or removed.
                       *
                       * Requirements:
                       *
                       * - `index` must be strictly less than {length}.
                       */
                      function _at(Set storage set, uint256 index) private view returns (bytes32) {
                          return set._values[index];
                      }
                      /**
                       * @dev Return the entire set in an array
                       *
                       * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
                       * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
                       * this function has an unbounded cost, and using it as part of a state-changing function may render the function
                       * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
                       */
                      function _values(Set storage set) private view returns (bytes32[] memory) {
                          return set._values;
                      }
                      // Bytes32Set
                      struct Bytes32Set {
                          Set _inner;
                      }
                      /**
                       * @dev Add a value to a set. O(1).
                       *
                       * Returns true if the value was added to the set, that is if it was not
                       * already present.
                       */
                      function add(Bytes32Set storage set, bytes32 value) internal returns (bool) {
                          return _add(set._inner, value);
                      }
                      /**
                       * @dev Removes a value from a set. O(1).
                       *
                       * Returns true if the value was removed from the set, that is if it was
                       * present.
                       */
                      function remove(Bytes32Set storage set, bytes32 value) internal returns (bool) {
                          return _remove(set._inner, value);
                      }
                      /**
                       * @dev Returns true if the value is in the set. O(1).
                       */
                      function contains(Bytes32Set storage set, bytes32 value) internal view returns (bool) {
                          return _contains(set._inner, value);
                      }
                      /**
                       * @dev Returns the number of values in the set. O(1).
                       */
                      function length(Bytes32Set storage set) internal view returns (uint256) {
                          return _length(set._inner);
                      }
                      /**
                       * @dev Returns the value stored at position `index` in the set. O(1).
                       *
                       * Note that there are no guarantees on the ordering of values inside the
                       * array, and it may change when more values are added or removed.
                       *
                       * Requirements:
                       *
                       * - `index` must be strictly less than {length}.
                       */
                      function at(Bytes32Set storage set, uint256 index) internal view returns (bytes32) {
                          return _at(set._inner, index);
                      }
                      /**
                       * @dev Return the entire set in an array
                       *
                       * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
                       * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
                       * this function has an unbounded cost, and using it as part of a state-changing function may render the function
                       * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
                       */
                      function values(Bytes32Set storage set) internal view returns (bytes32[] memory) {
                          bytes32[] memory store = _values(set._inner);
                          bytes32[] memory result;
                          /// @solidity memory-safe-assembly
                          assembly {
                              result := store
                          }
                          return result;
                      }
                      // AddressSet
                      struct AddressSet {
                          Set _inner;
                      }
                      /**
                       * @dev Add a value to a set. O(1).
                       *
                       * Returns true if the value was added to the set, that is if it was not
                       * already present.
                       */
                      function add(AddressSet storage set, address value) internal returns (bool) {
                          return _add(set._inner, bytes32(uint256(uint160(value))));
                      }
                      /**
                       * @dev Removes a value from a set. O(1).
                       *
                       * Returns true if the value was removed from the set, that is if it was
                       * present.
                       */
                      function remove(AddressSet storage set, address value) internal returns (bool) {
                          return _remove(set._inner, bytes32(uint256(uint160(value))));
                      }
                      /**
                       * @dev Returns true if the value is in the set. O(1).
                       */
                      function contains(AddressSet storage set, address value) internal view returns (bool) {
                          return _contains(set._inner, bytes32(uint256(uint160(value))));
                      }
                      /**
                       * @dev Returns the number of values in the set. O(1).
                       */
                      function length(AddressSet storage set) internal view returns (uint256) {
                          return _length(set._inner);
                      }
                      /**
                       * @dev Returns the value stored at position `index` in the set. O(1).
                       *
                       * Note that there are no guarantees on the ordering of values inside the
                       * array, and it may change when more values are added or removed.
                       *
                       * Requirements:
                       *
                       * - `index` must be strictly less than {length}.
                       */
                      function at(AddressSet storage set, uint256 index) internal view returns (address) {
                          return address(uint160(uint256(_at(set._inner, index))));
                      }
                      /**
                       * @dev Return the entire set in an array
                       *
                       * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
                       * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
                       * this function has an unbounded cost, and using it as part of a state-changing function may render the function
                       * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
                       */
                      function values(AddressSet storage set) internal view returns (address[] memory) {
                          bytes32[] memory store = _values(set._inner);
                          address[] memory result;
                          /// @solidity memory-safe-assembly
                          assembly {
                              result := store
                          }
                          return result;
                      }
                      // UintSet
                      struct UintSet {
                          Set _inner;
                      }
                      /**
                       * @dev Add a value to a set. O(1).
                       *
                       * Returns true if the value was added to the set, that is if it was not
                       * already present.
                       */
                      function add(UintSet storage set, uint256 value) internal returns (bool) {
                          return _add(set._inner, bytes32(value));
                      }
                      /**
                       * @dev Removes a value from a set. O(1).
                       *
                       * Returns true if the value was removed from the set, that is if it was
                       * present.
                       */
                      function remove(UintSet storage set, uint256 value) internal returns (bool) {
                          return _remove(set._inner, bytes32(value));
                      }
                      /**
                       * @dev Returns true if the value is in the set. O(1).
                       */
                      function contains(UintSet storage set, uint256 value) internal view returns (bool) {
                          return _contains(set._inner, bytes32(value));
                      }
                      /**
                       * @dev Returns the number of values in the set. O(1).
                       */
                      function length(UintSet storage set) internal view returns (uint256) {
                          return _length(set._inner);
                      }
                      /**
                       * @dev Returns the value stored at position `index` in the set. O(1).
                       *
                       * Note that there are no guarantees on the ordering of values inside the
                       * array, and it may change when more values are added or removed.
                       *
                       * Requirements:
                       *
                       * - `index` must be strictly less than {length}.
                       */
                      function at(UintSet storage set, uint256 index) internal view returns (uint256) {
                          return uint256(_at(set._inner, index));
                      }
                      /**
                       * @dev Return the entire set in an array
                       *
                       * WARNING: This operation will copy the entire storage to memory, which can be quite expensive. This is designed
                       * to mostly be used by view accessors that are queried without any gas fees. Developers should keep in mind that
                       * this function has an unbounded cost, and using it as part of a state-changing function may render the function
                       * uncallable if the set grows to a point where copying to memory consumes too much gas to fit in a block.
                       */
                      function values(UintSet storage set) internal view returns (uint256[] memory) {
                          bytes32[] memory store = _values(set._inner);
                          uint256[] memory result;
                          /// @solidity memory-safe-assembly
                          assembly {
                              result := store
                          }
                          return result;
                      }
                  }
                  // SPDX-License-Identifier: MIT
                  // OpenZeppelin Contracts (last updated v4.8.0) (access/AccessControl.sol)
                  pragma solidity ^0.8.0;
                  import "./IAccessControl.sol";
                  import "../utils/Context.sol";
                  import "../utils/Strings.sol";
                  import "../utils/introspection/ERC165.sol";
                  /**
                   * @dev Contract module that allows children to implement role-based access
                   * control mechanisms. This is a lightweight version that doesn't allow enumerating role
                   * members except through off-chain means by accessing the contract event logs. Some
                   * applications may benefit from on-chain enumerability, for those cases see
                   * {AccessControlEnumerable}.
                   *
                   * Roles are referred to by their `bytes32` identifier. These should be exposed
                   * in the external API and be unique. The best way to achieve this is by
                   * using `public constant` hash digests:
                   *
                   * ```
                   * bytes32 public constant MY_ROLE = keccak256("MY_ROLE");
                   * ```
                   *
                   * Roles can be used to represent a set of permissions. To restrict access to a
                   * function call, use {hasRole}:
                   *
                   * ```
                   * function foo() public {
                   *     require(hasRole(MY_ROLE, msg.sender));
                   *     ...
                   * }
                   * ```
                   *
                   * Roles can be granted and revoked dynamically via the {grantRole} and
                   * {revokeRole} functions. Each role has an associated admin role, and only
                   * accounts that have a role's admin role can call {grantRole} and {revokeRole}.
                   *
                   * By default, the admin role for all roles is `DEFAULT_ADMIN_ROLE`, which means
                   * that only accounts with this role will be able to grant or revoke other
                   * roles. More complex role relationships can be created by using
                   * {_setRoleAdmin}.
                   *
                   * WARNING: The `DEFAULT_ADMIN_ROLE` is also its own admin: it has permission to
                   * grant and revoke this role. Extra precautions should be taken to secure
                   * accounts that have been granted it.
                   */
                  abstract contract AccessControl is Context, IAccessControl, ERC165 {
                      struct RoleData {
                          mapping(address => bool) members;
                          bytes32 adminRole;
                      }
                      mapping(bytes32 => RoleData) private _roles;
                      bytes32 public constant DEFAULT_ADMIN_ROLE = 0x00;
                      /**
                       * @dev Modifier that checks that an account has a specific role. Reverts
                       * with a standardized message including the required role.
                       *
                       * The format of the revert reason is given by the following regular expression:
                       *
                       *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
                       *
                       * _Available since v4.1._
                       */
                      modifier onlyRole(bytes32 role) {
                          _checkRole(role);
                          _;
                      }
                      /**
                       * @dev See {IERC165-supportsInterface}.
                       */
                      function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
                          return interfaceId == type(IAccessControl).interfaceId || super.supportsInterface(interfaceId);
                      }
                      /**
                       * @dev Returns `true` if `account` has been granted `role`.
                       */
                      function hasRole(bytes32 role, address account) public view virtual override returns (bool) {
                          return _roles[role].members[account];
                      }
                      /**
                       * @dev Revert with a standard message if `_msgSender()` is missing `role`.
                       * Overriding this function changes the behavior of the {onlyRole} modifier.
                       *
                       * Format of the revert message is described in {_checkRole}.
                       *
                       * _Available since v4.6._
                       */
                      function _checkRole(bytes32 role) internal view virtual {
                          _checkRole(role, _msgSender());
                      }
                      /**
                       * @dev Revert with a standard message if `account` is missing `role`.
                       *
                       * The format of the revert reason is given by the following regular expression:
                       *
                       *  /^AccessControl: account (0x[0-9a-f]{40}) is missing role (0x[0-9a-f]{64})$/
                       */
                      function _checkRole(bytes32 role, address account) internal view virtual {
                          if (!hasRole(role, account)) {
                              revert(
                                  string(
                                      abi.encodePacked(
                                          "AccessControl: account ",
                                          Strings.toHexString(account),
                                          " is missing role ",
                                          Strings.toHexString(uint256(role), 32)
                                      )
                                  )
                              );
                          }
                      }
                      /**
                       * @dev Returns the admin role that controls `role`. See {grantRole} and
                       * {revokeRole}.
                       *
                       * To change a role's admin, use {_setRoleAdmin}.
                       */
                      function getRoleAdmin(bytes32 role) public view virtual override returns (bytes32) {
                          return _roles[role].adminRole;
                      }
                      /**
                       * @dev Grants `role` to `account`.
                       *
                       * If `account` had not been already granted `role`, emits a {RoleGranted}
                       * event.
                       *
                       * Requirements:
                       *
                       * - the caller must have ``role``'s admin role.
                       *
                       * May emit a {RoleGranted} event.
                       */
                      function grantRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
                          _grantRole(role, account);
                      }
                      /**
                       * @dev Revokes `role` from `account`.
                       *
                       * If `account` had been granted `role`, emits a {RoleRevoked} event.
                       *
                       * Requirements:
                       *
                       * - the caller must have ``role``'s admin role.
                       *
                       * May emit a {RoleRevoked} event.
                       */
                      function revokeRole(bytes32 role, address account) public virtual override onlyRole(getRoleAdmin(role)) {
                          _revokeRole(role, account);
                      }
                      /**
                       * @dev Revokes `role` from the calling account.
                       *
                       * Roles are often managed via {grantRole} and {revokeRole}: this function's
                       * purpose is to provide a mechanism for accounts to lose their privileges
                       * if they are compromised (such as when a trusted device is misplaced).
                       *
                       * If the calling account had been revoked `role`, emits a {RoleRevoked}
                       * event.
                       *
                       * Requirements:
                       *
                       * - the caller must be `account`.
                       *
                       * May emit a {RoleRevoked} event.
                       */
                      function renounceRole(bytes32 role, address account) public virtual override {
                          require(account == _msgSender(), "AccessControl: can only renounce roles for self");
                          _revokeRole(role, account);
                      }
                      /**
                       * @dev Grants `role` to `account`.
                       *
                       * If `account` had not been already granted `role`, emits a {RoleGranted}
                       * event. Note that unlike {grantRole}, this function doesn't perform any
                       * checks on the calling account.
                       *
                       * May emit a {RoleGranted} event.
                       *
                       * [WARNING]
                       * ====
                       * This function should only be called from the constructor when setting
                       * up the initial roles for the system.
                       *
                       * Using this function in any other way is effectively circumventing the admin
                       * system imposed by {AccessControl}.
                       * ====
                       *
                       * NOTE: This function is deprecated in favor of {_grantRole}.
                       */
                      function _setupRole(bytes32 role, address account) internal virtual {
                          _grantRole(role, account);
                      }
                      /**
                       * @dev Sets `adminRole` as ``role``'s admin role.
                       *
                       * Emits a {RoleAdminChanged} event.
                       */
                      function _setRoleAdmin(bytes32 role, bytes32 adminRole) internal virtual {
                          bytes32 previousAdminRole = getRoleAdmin(role);
                          _roles[role].adminRole = adminRole;
                          emit RoleAdminChanged(role, previousAdminRole, adminRole);
                      }
                      /**
                       * @dev Grants `role` to `account`.
                       *
                       * Internal function without access restriction.
                       *
                       * May emit a {RoleGranted} event.
                       */
                      function _grantRole(bytes32 role, address account) internal virtual {
                          if (!hasRole(role, account)) {
                              _roles[role].members[account] = true;
                              emit RoleGranted(role, account, _msgSender());
                          }
                      }
                      /**
                       * @dev Revokes `role` from `account`.
                       *
                       * Internal function without access restriction.
                       *
                       * May emit a {RoleRevoked} event.
                       */
                      function _revokeRole(bytes32 role, address account) internal virtual {
                          if (hasRole(role, account)) {
                              _roles[role].members[account] = false;
                              emit RoleRevoked(role, account, _msgSender());
                          }
                      }
                  }
                  // SPDX-License-Identifier: MIT-only
                  pragma solidity ^0.8.0;
                  import {IERC20} from '@openzeppelin/contracts/token/ERC20/IERC20.sol';
                  /**
                   * @title ERC20
                   * @notice Gas Efficient ERC20 + EIP-2612 implementation
                   * @dev Modified version of Solmate ERC20 (https://github.com/Rari-Capital/solmate/blob/main/src/tokens/ERC20.sol),
                   * implementing the basic IERC20
                   */
                  abstract contract ERC20 is IERC20 {
                    /*///////////////////////////////////////////////////////////////
                                               METADATA STORAGE
                      //////////////////////////////////////////////////////////////*/
                    string public name;
                    string public symbol;
                    uint8 public immutable decimals;
                    /*///////////////////////////////////////////////////////////////
                                                ERC20 STORAGE
                      //////////////////////////////////////////////////////////////*/
                    uint256 public totalSupply;
                    mapping(address => uint256) public balanceOf;
                    mapping(address => mapping(address => uint256)) public allowance;
                    /*///////////////////////////////////////////////////////////////
                                               EIP-2612 STORAGE
                      //////////////////////////////////////////////////////////////*/
                    bytes32 public constant PERMIT_TYPEHASH =
                      keccak256('Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)');
                    uint256 internal immutable INITIAL_CHAIN_ID;
                    bytes32 internal immutable INITIAL_DOMAIN_SEPARATOR;
                    mapping(address => uint256) public nonces;
                    /*///////////////////////////////////////////////////////////////
                                                 CONSTRUCTOR
                      //////////////////////////////////////////////////////////////*/
                    constructor(string memory _name, string memory _symbol, uint8 _decimals) {
                      name = _name;
                      symbol = _symbol;
                      decimals = _decimals;
                      INITIAL_CHAIN_ID = block.chainid;
                      INITIAL_DOMAIN_SEPARATOR = computeDomainSeparator();
                    }
                    /*///////////////////////////////////////////////////////////////
                                                ERC20 LOGIC
                      //////////////////////////////////////////////////////////////*/
                    function approve(address spender, uint256 amount) public virtual returns (bool) {
                      allowance[msg.sender][spender] = amount;
                      emit Approval(msg.sender, spender, amount);
                      return true;
                    }
                    function transfer(address to, uint256 amount) public virtual returns (bool) {
                      balanceOf[msg.sender] -= amount;
                      // Cannot overflow because the sum of all user
                      // balances can't exceed the max uint256 value.
                      unchecked {
                        balanceOf[to] += amount;
                      }
                      emit Transfer(msg.sender, to, amount);
                      return true;
                    }
                    function transferFrom(address from, address to, uint256 amount) public virtual returns (bool) {
                      uint256 allowed = allowance[from][msg.sender]; // Saves gas for limited approvals.
                      if (allowed != type(uint256).max) allowance[from][msg.sender] = allowed - amount;
                      balanceOf[from] -= amount;
                      // Cannot overflow because the sum of all user
                      // balances can't exceed the max uint256 value.
                      unchecked {
                        balanceOf[to] += amount;
                      }
                      emit Transfer(from, to, amount);
                      return true;
                    }
                    /*///////////////////////////////////////////////////////////////
                                                EIP-2612 LOGIC
                      //////////////////////////////////////////////////////////////*/
                    function permit(
                      address owner,
                      address spender,
                      uint256 value,
                      uint256 deadline,
                      uint8 v,
                      bytes32 r,
                      bytes32 s
                    ) public virtual {
                      require(deadline >= block.timestamp, 'PERMIT_DEADLINE_EXPIRED');
                      // Unchecked because the only math done is incrementing
                      // the owner's nonce which cannot realistically overflow.
                      unchecked {
                        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, 'INVALID_SIGNER');
                        allowance[recoveredAddress][spender] = value;
                      }
                      emit Approval(owner, spender, value);
                    }
                    function DOMAIN_SEPARATOR() public view virtual returns (bytes32) {
                      return block.chainid == INITIAL_CHAIN_ID ? INITIAL_DOMAIN_SEPARATOR : computeDomainSeparator();
                    }
                    function computeDomainSeparator() internal view virtual returns (bytes32) {
                      return
                        keccak256(
                          abi.encode(
                            keccak256(
                              'EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)'
                            ),
                            keccak256(bytes(name)),
                            keccak256('1'),
                            block.chainid,
                            address(this)
                          )
                        );
                    }
                    /*///////////////////////////////////////////////////////////////
                                         INTERNAL MINT/BURN LOGIC
                      //////////////////////////////////////////////////////////////*/
                    function _mint(address to, uint256 amount) internal virtual {
                      totalSupply += amount;
                      // Cannot overflow because the sum of all user
                      // balances can't exceed the max uint256 value.
                      unchecked {
                        balanceOf[to] += amount;
                      }
                      emit Transfer(address(0), to, amount);
                    }
                    function _burn(address from, uint256 amount) internal virtual {
                      balanceOf[from] -= amount;
                      // Cannot underflow because a user's balance
                      // will never be larger than the total supply.
                      unchecked {
                        totalSupply -= amount;
                      }
                      emit Transfer(from, address(0), amount);
                    }
                  }
                  // SPDX-License-Identifier: MIT
                  pragma solidity ^0.8.0;
                  import {IERC20} from '@openzeppelin/contracts/token/ERC20/IERC20.sol';
                  import {IAccessControl} from '@openzeppelin/contracts/access/IAccessControl.sol';
                  /**
                   * @title IGhoToken
                   * @author Aave
                   */
                  interface IGhoToken is IERC20, IAccessControl {
                    struct Facilitator {
                      uint128 bucketCapacity;
                      uint128 bucketLevel;
                      string label;
                    }
                    /**
                     * @dev Emitted when a new facilitator is added
                     * @param facilitatorAddress The address of the new facilitator
                     * @param label A hashed human readable identifier for the facilitator
                     * @param bucketCapacity The initial capacity of the facilitator's bucket
                     */
                    event FacilitatorAdded(
                      address indexed facilitatorAddress,
                      bytes32 indexed label,
                      uint256 bucketCapacity
                    );
                    /**
                     * @dev Emitted when a facilitator is removed
                     * @param facilitatorAddress The address of the removed facilitator
                     */
                    event FacilitatorRemoved(address indexed facilitatorAddress);
                    /**
                     * @dev Emitted when the bucket capacity of a facilitator is updated
                     * @param facilitatorAddress The address of the facilitator whose bucket capacity is being changed
                     * @param oldCapacity The old capacity of the bucket
                     * @param newCapacity The new capacity of the bucket
                     */
                    event FacilitatorBucketCapacityUpdated(
                      address indexed facilitatorAddress,
                      uint256 oldCapacity,
                      uint256 newCapacity
                    );
                    /**
                     * @dev Emitted when the bucket level changed
                     * @param facilitatorAddress The address of the facilitator whose bucket level is being changed
                     * @param oldLevel The old level of the bucket
                     * @param newLevel The new level of the bucket
                     */
                    event FacilitatorBucketLevelUpdated(
                      address indexed facilitatorAddress,
                      uint256 oldLevel,
                      uint256 newLevel
                    );
                    /**
                     * @notice Returns the identifier of the Facilitator Manager Role
                     * @return The bytes32 id hash of the FacilitatorManager role
                     */
                    function FACILITATOR_MANAGER_ROLE() external pure returns (bytes32);
                    /**
                     * @notice Returns the identifier of the Bucket Manager Role
                     * @return The bytes32 id hash of the BucketManager role
                     */
                    function BUCKET_MANAGER_ROLE() external pure returns (bytes32);
                    /**
                     * @notice Mints the requested amount of tokens to the account address.
                     * @dev Only facilitators with enough bucket capacity available can mint.
                     * @dev The bucket level is increased upon minting.
                     * @param account The address receiving the GHO tokens
                     * @param amount The amount to mint
                     */
                    function mint(address account, uint256 amount) external;
                    /**
                     * @notice Burns the requested amount of tokens from the account address.
                     * @dev Only active facilitators (bucket level > 0) can burn.
                     * @dev The bucket level is decreased upon burning.
                     * @param amount The amount to burn
                     */
                    function burn(uint256 amount) external;
                    /**
                     * @notice Add the facilitator passed with the parameters to the facilitators list.
                     * @dev Only accounts with `FACILITATOR_MANAGER_ROLE` role can call this function
                     * @param facilitatorAddress The address of the facilitator to add
                     * @param facilitatorLabel A human readable identifier for the facilitator
                     * @param bucketCapacity The upward limit of GHO can be minted by the facilitator
                     */
                    function addFacilitator(
                      address facilitatorAddress,
                      string calldata facilitatorLabel,
                      uint128 bucketCapacity
                    ) external;
                    /**
                     * @notice Remove the facilitator from the facilitators list.
                     * @dev Only accounts with `FACILITATOR_MANAGER_ROLE` role can call this function
                     * @param facilitatorAddress The address of the facilitator to remove
                     */
                    function removeFacilitator(address facilitatorAddress) external;
                    /**
                     * @notice Set the bucket capacity of the facilitator.
                     * @dev Only accounts with `BUCKET_MANAGER_ROLE` role can call this function
                     * @param facilitator The address of the facilitator
                     * @param newCapacity The new capacity of the bucket
                     */
                    function setFacilitatorBucketCapacity(address facilitator, uint128 newCapacity) external;
                    /**
                     * @notice Returns the facilitator data
                     * @param facilitator The address of the facilitator
                     * @return The facilitator configuration
                     */
                    function getFacilitator(address facilitator) external view returns (Facilitator memory);
                    /**
                     * @notice Returns the bucket configuration of the facilitator
                     * @param facilitator The address of the facilitator
                     * @return The capacity of the facilitator's bucket
                     * @return The level of the facilitator's bucket
                     */
                    function getFacilitatorBucket(address facilitator) external view returns (uint256, uint256);
                    /**
                     * @notice Returns the list of the addresses of the active facilitator
                     * @return The list of the facilitators addresses
                     */
                    function getFacilitatorsList() external view returns (address[] memory);
                  }
                  // SPDX-License-Identifier: MIT
                  // OpenZeppelin Contracts v4.4.1 (access/IAccessControl.sol)
                  pragma solidity ^0.8.0;
                  /**
                   * @dev External interface of AccessControl declared to support ERC165 detection.
                   */
                  interface IAccessControl {
                      /**
                       * @dev Emitted when `newAdminRole` is set as ``role``'s admin role, replacing `previousAdminRole`
                       *
                       * `DEFAULT_ADMIN_ROLE` is the starting admin for all roles, despite
                       * {RoleAdminChanged} not being emitted signaling this.
                       *
                       * _Available since v3.1._
                       */
                      event RoleAdminChanged(bytes32 indexed role, bytes32 indexed previousAdminRole, bytes32 indexed newAdminRole);
                      /**
                       * @dev Emitted when `account` is granted `role`.
                       *
                       * `sender` is the account that originated the contract call, an admin role
                       * bearer except when using {AccessControl-_setupRole}.
                       */
                      event RoleGranted(bytes32 indexed role, address indexed account, address indexed sender);
                      /**
                       * @dev Emitted when `account` is revoked `role`.
                       *
                       * `sender` is the account that originated the contract call:
                       *   - if using `revokeRole`, it is the admin role bearer
                       *   - if using `renounceRole`, it is the role bearer (i.e. `account`)
                       */
                      event RoleRevoked(bytes32 indexed role, address indexed account, address indexed sender);
                      /**
                       * @dev Returns `true` if `account` has been granted `role`.
                       */
                      function hasRole(bytes32 role, address account) external view returns (bool);
                      /**
                       * @dev Returns the admin role that controls `role`. See {grantRole} and
                       * {revokeRole}.
                       *
                       * To change a role's admin, use {AccessControl-_setRoleAdmin}.
                       */
                      function getRoleAdmin(bytes32 role) external view returns (bytes32);
                      /**
                       * @dev Grants `role` to `account`.
                       *
                       * If `account` had not been already granted `role`, emits a {RoleGranted}
                       * event.
                       *
                       * Requirements:
                       *
                       * - the caller must have ``role``'s admin role.
                       */
                      function grantRole(bytes32 role, address account) external;
                      /**
                       * @dev Revokes `role` from `account`.
                       *
                       * If `account` had been granted `role`, emits a {RoleRevoked} event.
                       *
                       * Requirements:
                       *
                       * - the caller must have ``role``'s admin role.
                       */
                      function revokeRole(bytes32 role, address account) external;
                      /**
                       * @dev Revokes `role` from the calling account.
                       *
                       * Roles are often managed via {grantRole} and {revokeRole}: this function's
                       * purpose is to provide a mechanism for accounts to lose their privileges
                       * if they are compromised (such as when a trusted device is misplaced).
                       *
                       * If the calling account had been granted `role`, emits a {RoleRevoked}
                       * event.
                       *
                       * Requirements:
                       *
                       * - the caller must be `account`.
                       */
                      function renounceRole(bytes32 role, address account) external;
                  }
                  // SPDX-License-Identifier: MIT
                  // OpenZeppelin Contracts v4.4.1 (utils/Context.sol)
                  pragma solidity ^0.8.0;
                  /**
                   * @dev Provides information about the current execution context, including the
                   * sender of the transaction and its data. While these are generally available
                   * via msg.sender and msg.data, they should not be accessed in such a direct
                   * manner, since when dealing with meta-transactions the account sending and
                   * paying for execution may not be the actual sender (as far as an application
                   * is concerned).
                   *
                   * This contract is only required for intermediate, library-like contracts.
                   */
                  abstract contract Context {
                      function _msgSender() internal view virtual returns (address) {
                          return msg.sender;
                      }
                      function _msgData() internal view virtual returns (bytes calldata) {
                          return msg.data;
                      }
                  }
                  // SPDX-License-Identifier: MIT
                  // OpenZeppelin Contracts (last updated v4.8.0) (utils/Strings.sol)
                  pragma solidity ^0.8.0;
                  import "./math/Math.sol";
                  /**
                   * @dev String operations.
                   */
                  library Strings {
                      bytes16 private constant _SYMBOLS = "0123456789abcdef";
                      uint8 private constant _ADDRESS_LENGTH = 20;
                      /**
                       * @dev Converts a `uint256` to its ASCII `string` decimal representation.
                       */
                      function toString(uint256 value) internal pure returns (string memory) {
                          unchecked {
                              uint256 length = Math.log10(value) + 1;
                              string memory buffer = new string(length);
                              uint256 ptr;
                              /// @solidity memory-safe-assembly
                              assembly {
                                  ptr := add(buffer, add(32, length))
                              }
                              while (true) {
                                  ptr--;
                                  /// @solidity memory-safe-assembly
                                  assembly {
                                      mstore8(ptr, byte(mod(value, 10), _SYMBOLS))
                                  }
                                  value /= 10;
                                  if (value == 0) break;
                              }
                              return buffer;
                          }
                      }
                      /**
                       * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation.
                       */
                      function toHexString(uint256 value) internal pure returns (string memory) {
                          unchecked {
                              return toHexString(value, Math.log256(value) + 1);
                          }
                      }
                      /**
                       * @dev Converts a `uint256` to its ASCII `string` hexadecimal representation with fixed length.
                       */
                      function toHexString(uint256 value, uint256 length) internal pure returns (string memory) {
                          bytes memory buffer = new bytes(2 * length + 2);
                          buffer[0] = "0";
                          buffer[1] = "x";
                          for (uint256 i = 2 * length + 1; i > 1; --i) {
                              buffer[i] = _SYMBOLS[value & 0xf];
                              value >>= 4;
                          }
                          require(value == 0, "Strings: hex length insufficient");
                          return string(buffer);
                      }
                      /**
                       * @dev Converts an `address` with fixed length of 20 bytes to its not checksummed ASCII `string` hexadecimal representation.
                       */
                      function toHexString(address addr) internal pure returns (string memory) {
                          return toHexString(uint256(uint160(addr)), _ADDRESS_LENGTH);
                      }
                  }
                  // SPDX-License-Identifier: MIT
                  // OpenZeppelin Contracts v4.4.1 (utils/introspection/ERC165.sol)
                  pragma solidity ^0.8.0;
                  import "./IERC165.sol";
                  /**
                   * @dev Implementation of the {IERC165} interface.
                   *
                   * Contracts that want to implement ERC165 should inherit from this contract and override {supportsInterface} to check
                   * for the additional interface id that will be supported. For example:
                   *
                   * ```solidity
                   * function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
                   *     return interfaceId == type(MyInterface).interfaceId || super.supportsInterface(interfaceId);
                   * }
                   * ```
                   *
                   * Alternatively, {ERC165Storage} provides an easier to use but more expensive implementation.
                   */
                  abstract contract ERC165 is IERC165 {
                      /**
                       * @dev See {IERC165-supportsInterface}.
                       */
                      function supportsInterface(bytes4 interfaceId) public view virtual override returns (bool) {
                          return interfaceId == type(IERC165).interfaceId;
                      }
                  }
                  // SPDX-License-Identifier: MIT
                  // OpenZeppelin Contracts (last updated v4.6.0) (token/ERC20/IERC20.sol)
                  pragma solidity ^0.8.0;
                  /**
                   * @dev Interface of the ERC20 standard as defined in the EIP.
                   */
                  interface IERC20 {
                      /**
                       * @dev Emitted when `value` tokens are moved from one account (`from`) to
                       * another (`to`).
                       *
                       * Note that `value` may be zero.
                       */
                      event Transfer(address indexed from, address indexed to, uint256 value);
                      /**
                       * @dev Emitted when the allowance of a `spender` for an `owner` is set by
                       * a call to {approve}. `value` is the new allowance.
                       */
                      event Approval(address indexed owner, address indexed spender, uint256 value);
                      /**
                       * @dev Returns the amount of tokens in existence.
                       */
                      function totalSupply() external view returns (uint256);
                      /**
                       * @dev Returns the amount of tokens owned by `account`.
                       */
                      function balanceOf(address account) external view returns (uint256);
                      /**
                       * @dev Moves `amount` tokens from the caller's account to `to`.
                       *
                       * Returns a boolean value indicating whether the operation succeeded.
                       *
                       * Emits a {Transfer} event.
                       */
                      function transfer(address to, uint256 amount) external returns (bool);
                      /**
                       * @dev Returns the remaining number of tokens that `spender` will be
                       * allowed to spend on behalf of `owner` through {transferFrom}. This is
                       * zero by default.
                       *
                       * This value changes when {approve} or {transferFrom} are called.
                       */
                      function allowance(address owner, address spender) external view returns (uint256);
                      /**
                       * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
                       *
                       * Returns a boolean value indicating whether the operation succeeded.
                       *
                       * IMPORTANT: Beware that changing an allowance with this method brings the risk
                       * that someone may use both the old and the new allowance by unfortunate
                       * transaction ordering. One possible solution to mitigate this race
                       * condition is to first reduce the spender's allowance to 0 and set the
                       * desired value afterwards:
                       * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
                       *
                       * Emits an {Approval} event.
                       */
                      function approve(address spender, uint256 amount) external returns (bool);
                      /**
                       * @dev Moves `amount` tokens from `from` to `to` using the
                       * allowance mechanism. `amount` is then deducted from the caller's
                       * allowance.
                       *
                       * Returns a boolean value indicating whether the operation succeeded.
                       *
                       * Emits a {Transfer} event.
                       */
                      function transferFrom(
                          address from,
                          address to,
                          uint256 amount
                      ) external returns (bool);
                  }
                  // SPDX-License-Identifier: MIT
                  // OpenZeppelin Contracts (last updated v4.8.0) (utils/math/Math.sol)
                  pragma solidity ^0.8.0;
                  /**
                   * @dev Standard math utilities missing in the Solidity language.
                   */
                  library Math {
                      enum Rounding {
                          Down, // Toward negative infinity
                          Up, // Toward infinity
                          Zero // Toward zero
                      }
                      /**
                       * @dev Returns the largest of two numbers.
                       */
                      function max(uint256 a, uint256 b) internal pure returns (uint256) {
                          return a > b ? a : b;
                      }
                      /**
                       * @dev Returns the smallest of two numbers.
                       */
                      function min(uint256 a, uint256 b) internal pure returns (uint256) {
                          return a < b ? a : b;
                      }
                      /**
                       * @dev Returns the average of two numbers. The result is rounded towards
                       * zero.
                       */
                      function average(uint256 a, uint256 b) internal pure returns (uint256) {
                          // (a + b) / 2 can overflow.
                          return (a & b) + (a ^ b) / 2;
                      }
                      /**
                       * @dev Returns the ceiling of the division of two numbers.
                       *
                       * This differs from standard division with `/` in that it rounds up instead
                       * of rounding down.
                       */
                      function ceilDiv(uint256 a, uint256 b) internal pure returns (uint256) {
                          // (a + b - 1) / b can overflow on addition, so we distribute.
                          return a == 0 ? 0 : (a - 1) / b + 1;
                      }
                      /**
                       * @notice Calculates floor(x * y / denominator) with full precision. Throws if result overflows a uint256 or denominator == 0
                       * @dev Original credit to Remco Bloemen under MIT license (https://xn--2-umb.com/21/muldiv)
                       * with further edits by Uniswap Labs also under MIT license.
                       */
                      function mulDiv(
                          uint256 x,
                          uint256 y,
                          uint256 denominator
                      ) internal pure returns (uint256 result) {
                          unchecked {
                              // 512-bit multiply [prod1 prod0] = x * y. Compute the product mod 2^256 and mod 2^256 - 1, then use
                              // use the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256
                              // variables such that product = prod1 * 2^256 + prod0.
                              uint256 prod0; // Least significant 256 bits of the product
                              uint256 prod1; // Most significant 256 bits of the product
                              assembly {
                                  let mm := mulmod(x, y, not(0))
                                  prod0 := mul(x, y)
                                  prod1 := sub(sub(mm, prod0), lt(mm, prod0))
                              }
                              // Handle non-overflow cases, 256 by 256 division.
                              if (prod1 == 0) {
                                  return prod0 / denominator;
                              }
                              // Make sure the result is less than 2^256. Also prevents denominator == 0.
                              require(denominator > prod1);
                              ///////////////////////////////////////////////
                              // 512 by 256 division.
                              ///////////////////////////////////////////////
                              // Make division exact by subtracting the remainder from [prod1 prod0].
                              uint256 remainder;
                              assembly {
                                  // Compute remainder using mulmod.
                                  remainder := mulmod(x, y, denominator)
                                  // Subtract 256 bit number from 512 bit number.
                                  prod1 := sub(prod1, gt(remainder, prod0))
                                  prod0 := sub(prod0, remainder)
                              }
                              // Factor powers of two out of denominator and compute largest power of two divisor of denominator. Always >= 1.
                              // See https://cs.stackexchange.com/q/138556/92363.
                              // Does not overflow because the denominator cannot be zero at this stage in the function.
                              uint256 twos = denominator & (~denominator + 1);
                              assembly {
                                  // Divide denominator by twos.
                                  denominator := div(denominator, twos)
                                  // Divide [prod1 prod0] by twos.
                                  prod0 := div(prod0, twos)
                                  // Flip twos such that it is 2^256 / twos. If twos is zero, then it becomes one.
                                  twos := add(div(sub(0, twos), twos), 1)
                              }
                              // Shift in bits from prod1 into prod0.
                              prod0 |= prod1 * twos;
                              // Invert denominator mod 2^256. Now that denominator is an odd number, it has an inverse modulo 2^256 such
                              // that denominator * inv = 1 mod 2^256. Compute the inverse by starting with a seed that is correct for
                              // four bits. That is, denominator * inv = 1 mod 2^4.
                              uint256 inverse = (3 * denominator) ^ 2;
                              // Use the Newton-Raphson iteration to improve the precision. Thanks to Hensel's lifting lemma, this also works
                              // in modular arithmetic, doubling the correct bits in each step.
                              inverse *= 2 - denominator * inverse; // inverse mod 2^8
                              inverse *= 2 - denominator * inverse; // inverse mod 2^16
                              inverse *= 2 - denominator * inverse; // inverse mod 2^32
                              inverse *= 2 - denominator * inverse; // inverse mod 2^64
                              inverse *= 2 - denominator * inverse; // inverse mod 2^128
                              inverse *= 2 - denominator * inverse; // inverse mod 2^256
                              // Because the division is now exact we can divide by multiplying with the modular inverse of denominator.
                              // This will give us the correct result modulo 2^256. Since the preconditions guarantee that the outcome is
                              // less than 2^256, this is the final result. We don't need to compute the high bits of the result and prod1
                              // is no longer required.
                              result = prod0 * inverse;
                              return result;
                          }
                      }
                      /**
                       * @notice Calculates x * y / denominator with full precision, following the selected rounding direction.
                       */
                      function mulDiv(
                          uint256 x,
                          uint256 y,
                          uint256 denominator,
                          Rounding rounding
                      ) internal pure returns (uint256) {
                          uint256 result = mulDiv(x, y, denominator);
                          if (rounding == Rounding.Up && mulmod(x, y, denominator) > 0) {
                              result += 1;
                          }
                          return result;
                      }
                      /**
                       * @dev Returns the square root of a number. If the number is not a perfect square, the value is rounded down.
                       *
                       * Inspired by Henry S. Warren, Jr.'s "Hacker's Delight" (Chapter 11).
                       */
                      function sqrt(uint256 a) internal pure returns (uint256) {
                          if (a == 0) {
                              return 0;
                          }
                          // For our first guess, we get the biggest power of 2 which is smaller than the square root of the target.
                          //
                          // We know that the "msb" (most significant bit) of our target number `a` is a power of 2 such that we have
                          // `msb(a) <= a < 2*msb(a)`. This value can be written `msb(a)=2**k` with `k=log2(a)`.
                          //
                          // This can be rewritten `2**log2(a) <= a < 2**(log2(a) + 1)`
                          // → `sqrt(2**k) <= sqrt(a) < sqrt(2**(k+1))`
                          // → `2**(k/2) <= sqrt(a) < 2**((k+1)/2) <= 2**(k/2 + 1)`
                          //
                          // Consequently, `2**(log2(a) / 2)` is a good first approximation of `sqrt(a)` with at least 1 correct bit.
                          uint256 result = 1 << (log2(a) >> 1);
                          // At this point `result` is an estimation with one bit of precision. We know the true value is a uint128,
                          // since it is the square root of a uint256. Newton's method converges quadratically (precision doubles at
                          // every iteration). We thus need at most 7 iteration to turn our partial result with one bit of precision
                          // into the expected uint128 result.
                          unchecked {
                              result = (result + a / result) >> 1;
                              result = (result + a / result) >> 1;
                              result = (result + a / result) >> 1;
                              result = (result + a / result) >> 1;
                              result = (result + a / result) >> 1;
                              result = (result + a / result) >> 1;
                              result = (result + a / result) >> 1;
                              return min(result, a / result);
                          }
                      }
                      /**
                       * @notice Calculates sqrt(a), following the selected rounding direction.
                       */
                      function sqrt(uint256 a, Rounding rounding) internal pure returns (uint256) {
                          unchecked {
                              uint256 result = sqrt(a);
                              return result + (rounding == Rounding.Up && result * result < a ? 1 : 0);
                          }
                      }
                      /**
                       * @dev Return the log in base 2, rounded down, of a positive value.
                       * Returns 0 if given 0.
                       */
                      function log2(uint256 value) internal pure returns (uint256) {
                          uint256 result = 0;
                          unchecked {
                              if (value >> 128 > 0) {
                                  value >>= 128;
                                  result += 128;
                              }
                              if (value >> 64 > 0) {
                                  value >>= 64;
                                  result += 64;
                              }
                              if (value >> 32 > 0) {
                                  value >>= 32;
                                  result += 32;
                              }
                              if (value >> 16 > 0) {
                                  value >>= 16;
                                  result += 16;
                              }
                              if (value >> 8 > 0) {
                                  value >>= 8;
                                  result += 8;
                              }
                              if (value >> 4 > 0) {
                                  value >>= 4;
                                  result += 4;
                              }
                              if (value >> 2 > 0) {
                                  value >>= 2;
                                  result += 2;
                              }
                              if (value >> 1 > 0) {
                                  result += 1;
                              }
                          }
                          return result;
                      }
                      /**
                       * @dev Return the log in base 2, following the selected rounding direction, of a positive value.
                       * Returns 0 if given 0.
                       */
                      function log2(uint256 value, Rounding rounding) internal pure returns (uint256) {
                          unchecked {
                              uint256 result = log2(value);
                              return result + (rounding == Rounding.Up && 1 << result < value ? 1 : 0);
                          }
                      }
                      /**
                       * @dev Return the log in base 10, rounded down, of a positive value.
                       * Returns 0 if given 0.
                       */
                      function log10(uint256 value) internal pure returns (uint256) {
                          uint256 result = 0;
                          unchecked {
                              if (value >= 10**64) {
                                  value /= 10**64;
                                  result += 64;
                              }
                              if (value >= 10**32) {
                                  value /= 10**32;
                                  result += 32;
                              }
                              if (value >= 10**16) {
                                  value /= 10**16;
                                  result += 16;
                              }
                              if (value >= 10**8) {
                                  value /= 10**8;
                                  result += 8;
                              }
                              if (value >= 10**4) {
                                  value /= 10**4;
                                  result += 4;
                              }
                              if (value >= 10**2) {
                                  value /= 10**2;
                                  result += 2;
                              }
                              if (value >= 10**1) {
                                  result += 1;
                              }
                          }
                          return result;
                      }
                      /**
                       * @dev Return the log in base 10, following the selected rounding direction, of a positive value.
                       * Returns 0 if given 0.
                       */
                      function log10(uint256 value, Rounding rounding) internal pure returns (uint256) {
                          unchecked {
                              uint256 result = log10(value);
                              return result + (rounding == Rounding.Up && 10**result < value ? 1 : 0);
                          }
                      }
                      /**
                       * @dev Return the log in base 256, rounded down, of a positive value.
                       * Returns 0 if given 0.
                       *
                       * Adding one to the result gives the number of pairs of hex symbols needed to represent `value` as a hex string.
                       */
                      function log256(uint256 value) internal pure returns (uint256) {
                          uint256 result = 0;
                          unchecked {
                              if (value >> 128 > 0) {
                                  value >>= 128;
                                  result += 16;
                              }
                              if (value >> 64 > 0) {
                                  value >>= 64;
                                  result += 8;
                              }
                              if (value >> 32 > 0) {
                                  value >>= 32;
                                  result += 4;
                              }
                              if (value >> 16 > 0) {
                                  value >>= 16;
                                  result += 2;
                              }
                              if (value >> 8 > 0) {
                                  result += 1;
                              }
                          }
                          return result;
                      }
                      /**
                       * @dev Return the log in base 10, following the selected rounding direction, of a positive value.
                       * Returns 0 if given 0.
                       */
                      function log256(uint256 value, Rounding rounding) internal pure returns (uint256) {
                          unchecked {
                              uint256 result = log256(value);
                              return result + (rounding == Rounding.Up && 1 << (result * 8) < value ? 1 : 0);
                          }
                      }
                  }
                  // SPDX-License-Identifier: MIT
                  // OpenZeppelin Contracts v4.4.1 (utils/introspection/IERC165.sol)
                  pragma solidity ^0.8.0;
                  /**
                   * @dev Interface of the ERC165 standard, as defined in the
                   * https://eips.ethereum.org/EIPS/eip-165[EIP].
                   *
                   * Implementers can declare support of contract interfaces, which can then be
                   * queried by others ({ERC165Checker}).
                   *
                   * For an implementation, see {ERC165}.
                   */
                  interface IERC165 {
                      /**
                       * @dev Returns true if this contract implements the interface defined by
                       * `interfaceId`. See the corresponding
                       * https://eips.ethereum.org/EIPS/eip-165#how-interfaces-are-identified[EIP section]
                       * to learn more about how these ids are created.
                       *
                       * This function call must use less than 30 000 gas.
                       */
                      function supportsInterface(bytes4 interfaceId) external view returns (bool);
                  }
                  

                  File 4 of 6: FiatTokenProxy
                  pragma solidity ^0.4.24;
                  
                  // File: zos-lib/contracts/upgradeability/Proxy.sol
                  
                  /**
                   * @title Proxy
                   * @dev Implements delegation of calls to other contracts, with proper
                   * forwarding of return values and bubbling of failures.
                   * It defines a fallback function that delegates all calls to the address
                   * returned by the abstract _implementation() internal function.
                   */
                  contract Proxy {
                    /**
                     * @dev Fallback function.
                     * Implemented entirely in `_fallback`.
                     */
                    function () payable external {
                      _fallback();
                    }
                  
                    /**
                     * @return The Address of the implementation.
                     */
                    function _implementation() internal view returns (address);
                  
                    /**
                     * @dev Delegates execution to an implementation contract.
                     * This is a low level function that doesn't return to its internal call site.
                     * It will return to the external caller whatever the implementation returns.
                     * @param implementation Address to delegate.
                     */
                    function _delegate(address implementation) internal {
                      assembly {
                        // Copy msg.data. We take full control of memory in this inline assembly
                        // block because it will not return to Solidity code. We overwrite the
                        // Solidity scratch pad at memory position 0.
                        calldatacopy(0, 0, calldatasize)
                  
                        // Call the implementation.
                        // out and outsize are 0 because we don't know the size yet.
                        let result := delegatecall(gas, implementation, 0, calldatasize, 0, 0)
                  
                        // Copy the returned data.
                        returndatacopy(0, 0, returndatasize)
                  
                        switch result
                        // delegatecall returns 0 on error.
                        case 0 { revert(0, returndatasize) }
                        default { return(0, returndatasize) }
                      }
                    }
                  
                    /**
                     * @dev Function that is run as the first thing in the fallback function.
                     * Can be redefined in derived contracts to add functionality.
                     * Redefinitions must call super._willFallback().
                     */
                    function _willFallback() internal {
                    }
                  
                    /**
                     * @dev fallback implementation.
                     * Extracted to enable manual triggering.
                     */
                    function _fallback() internal {
                      _willFallback();
                      _delegate(_implementation());
                    }
                  }
                  
                  // File: openzeppelin-solidity/contracts/AddressUtils.sol
                  
                  /**
                   * Utility library of inline functions on addresses
                   */
                  library AddressUtils {
                  
                    /**
                     * Returns whether the target address is a contract
                     * @dev This function will return false if invoked during the constructor of a contract,
                     * as the code is not actually created until after the constructor finishes.
                     * @param addr address to check
                     * @return whether the target address is a contract
                     */
                    function isContract(address addr) internal view returns (bool) {
                      uint256 size;
                      // XXX Currently there is no better way to check if there is a contract in an address
                      // than to check the size of the code at that address.
                      // See https://ethereum.stackexchange.com/a/14016/36603
                      // for more details about how this works.
                      // TODO Check this again before the Serenity release, because all addresses will be
                      // contracts then.
                      // solium-disable-next-line security/no-inline-assembly
                      assembly { size := extcodesize(addr) }
                      return size > 0;
                    }
                  
                  }
                  
                  // File: zos-lib/contracts/upgradeability/UpgradeabilityProxy.sol
                  
                  /**
                   * @title UpgradeabilityProxy
                   * @dev This contract implements a proxy that allows to change the
                   * implementation address to which it will delegate.
                   * Such a change is called an implementation upgrade.
                   */
                  contract UpgradeabilityProxy is Proxy {
                    /**
                     * @dev Emitted when the implementation is upgraded.
                     * @param implementation Address of the new implementation.
                     */
                    event Upgraded(address implementation);
                  
                    /**
                     * @dev Storage slot with the address of the current implementation.
                     * This is the keccak-256 hash of "org.zeppelinos.proxy.implementation", and is
                     * validated in the constructor.
                     */
                    bytes32 private constant IMPLEMENTATION_SLOT = 0x7050c9e0f4ca769c69bd3a8ef740bc37934f8e2c036e5a723fd8ee048ed3f8c3;
                  
                    /**
                     * @dev Contract constructor.
                     * @param _implementation Address of the initial implementation.
                     */
                    constructor(address _implementation) public {
                      assert(IMPLEMENTATION_SLOT == keccak256("org.zeppelinos.proxy.implementation"));
                  
                      _setImplementation(_implementation);
                    }
                  
                    /**
                     * @dev Returns the current implementation.
                     * @return Address of the current implementation
                     */
                    function _implementation() internal view returns (address impl) {
                      bytes32 slot = IMPLEMENTATION_SLOT;
                      assembly {
                        impl := sload(slot)
                      }
                    }
                  
                    /**
                     * @dev Upgrades the proxy to a new implementation.
                     * @param newImplementation Address of the new implementation.
                     */
                    function _upgradeTo(address newImplementation) internal {
                      _setImplementation(newImplementation);
                      emit Upgraded(newImplementation);
                    }
                  
                    /**
                     * @dev Sets the implementation address of the proxy.
                     * @param newImplementation Address of the new implementation.
                     */
                    function _setImplementation(address newImplementation) private {
                      require(AddressUtils.isContract(newImplementation), "Cannot set a proxy implementation to a non-contract address");
                  
                      bytes32 slot = IMPLEMENTATION_SLOT;
                  
                      assembly {
                        sstore(slot, newImplementation)
                      }
                    }
                  }
                  
                  // File: zos-lib/contracts/upgradeability/AdminUpgradeabilityProxy.sol
                  
                  /**
                   * @title AdminUpgradeabilityProxy
                   * @dev This contract combines an upgradeability proxy with an authorization
                   * mechanism for administrative tasks.
                   * All external functions in this contract must be guarded by the
                   * `ifAdmin` modifier. See ethereum/solidity#3864 for a Solidity
                   * feature proposal that would enable this to be done automatically.
                   */
                  contract AdminUpgradeabilityProxy is UpgradeabilityProxy {
                    /**
                     * @dev Emitted when the administration has been transferred.
                     * @param previousAdmin Address of the previous admin.
                     * @param newAdmin Address of the new admin.
                     */
                    event AdminChanged(address previousAdmin, address newAdmin);
                  
                    /**
                     * @dev Storage slot with the admin of the contract.
                     * This is the keccak-256 hash of "org.zeppelinos.proxy.admin", and is
                     * validated in the constructor.
                     */
                    bytes32 private constant ADMIN_SLOT = 0x10d6a54a4754c8869d6886b5f5d7fbfa5b4522237ea5c60d11bc4e7a1ff9390b;
                  
                    /**
                     * @dev Modifier to check whether the `msg.sender` is the admin.
                     * If it is, it will run the function. Otherwise, it will delegate the call
                     * to the implementation.
                     */
                    modifier ifAdmin() {
                      if (msg.sender == _admin()) {
                        _;
                      } else {
                        _fallback();
                      }
                    }
                  
                    /**
                     * Contract constructor.
                     * It sets the `msg.sender` as the proxy administrator.
                     * @param _implementation address of the initial implementation.
                     */
                    constructor(address _implementation) UpgradeabilityProxy(_implementation) public {
                      assert(ADMIN_SLOT == keccak256("org.zeppelinos.proxy.admin"));
                  
                      _setAdmin(msg.sender);
                    }
                  
                    /**
                     * @return The address of the proxy admin.
                     */
                    function admin() external view ifAdmin returns (address) {
                      return _admin();
                    }
                  
                    /**
                     * @return The address of the implementation.
                     */
                    function implementation() external view ifAdmin returns (address) {
                      return _implementation();
                    }
                  
                    /**
                     * @dev Changes the admin of the proxy.
                     * Only the current admin can call this function.
                     * @param newAdmin Address to transfer proxy administration to.
                     */
                    function changeAdmin(address newAdmin) external ifAdmin {
                      require(newAdmin != address(0), "Cannot change the admin of a proxy to the zero address");
                      emit AdminChanged(_admin(), newAdmin);
                      _setAdmin(newAdmin);
                    }
                  
                    /**
                     * @dev Upgrade the backing implementation of the proxy.
                     * Only the admin can call this function.
                     * @param newImplementation Address of the new implementation.
                     */
                    function upgradeTo(address newImplementation) external ifAdmin {
                      _upgradeTo(newImplementation);
                    }
                  
                    /**
                     * @dev Upgrade the backing implementation of the proxy and call a function
                     * on the new implementation.
                     * This is useful to initialize the proxied contract.
                     * @param newImplementation Address of the new implementation.
                     * @param data Data to send as msg.data in the low level call.
                     * It should include the signature and the parameters of the function to be
                     * called, as described in
                     * https://solidity.readthedocs.io/en/develop/abi-spec.html#function-selector-and-argument-encoding.
                     */
                    function upgradeToAndCall(address newImplementation, bytes data) payable external ifAdmin {
                      _upgradeTo(newImplementation);
                      require(address(this).call.value(msg.value)(data));
                    }
                  
                    /**
                     * @return The admin slot.
                     */
                    function _admin() internal view returns (address adm) {
                      bytes32 slot = ADMIN_SLOT;
                      assembly {
                        adm := sload(slot)
                      }
                    }
                  
                    /**
                     * @dev Sets the address of the proxy admin.
                     * @param newAdmin Address of the new proxy admin.
                     */
                    function _setAdmin(address newAdmin) internal {
                      bytes32 slot = ADMIN_SLOT;
                  
                      assembly {
                        sstore(slot, newAdmin)
                      }
                    }
                  
                    /**
                     * @dev Only fall back when the sender is not the admin.
                     */
                    function _willFallback() internal {
                      require(msg.sender != _admin(), "Cannot call fallback function from the proxy admin");
                      super._willFallback();
                    }
                  }
                  
                  // File: contracts/FiatTokenProxy.sol
                  
                  /**
                  * Copyright CENTRE SECZ 2018
                  *
                  * Permission is hereby granted, free of charge, to any person obtaining a copy 
                  * of this software and associated documentation files (the "Software"), to deal 
                  * in the Software without restriction, including without limitation the rights 
                  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
                  * copies of the Software, and to permit persons to whom the Software is furnished to 
                  * do so, subject to the following conditions:
                  *
                  * The above copyright notice and this permission notice shall be included in all 
                  * copies or substantial portions of the Software.
                  *
                  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
                  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
                  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
                  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
                  * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 
                  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
                  */
                  
                  pragma solidity ^0.4.24;
                  
                  
                  /**
                   * @title FiatTokenProxy
                   * @dev This contract proxies FiatToken calls and enables FiatToken upgrades
                  */ 
                  contract FiatTokenProxy is AdminUpgradeabilityProxy {
                      constructor(address _implementation) public AdminUpgradeabilityProxy(_implementation) {
                      }
                  }

                  File 5 of 6: UniswapV3Feature
                  // 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 "./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 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 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;
                  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 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;
                  library LibCommonRichErrors {
                      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 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 LibOwnableRichErrors {
                      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 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/IEtherToken.sol";
                  import "../vendor/IUniswapV3Pool.sol";
                  import "../migrations/LibMigrate.sol";
                  import "../fixins/FixinCommon.sol";
                  import "../fixins/FixinTokenSpender.sol";
                  import "./interfaces/IFeature.sol";
                  import "./interfaces/IUniswapV3Feature.sol";
                  /// @dev VIP uniswap fill functions.
                  contract UniswapV3Feature is IFeature, IUniswapV3Feature, FixinCommon, FixinTokenSpender {
                      /// @dev Name of this feature.
                      string public constant override FEATURE_NAME = "UniswapV3Feature";
                      /// @dev Version of this feature.
                      uint256 public immutable override FEATURE_VERSION = _encodeVersion(1, 1, 0);
                      /// @dev WETH contract.
                      IEtherToken private immutable WETH;
                      /// @dev UniswapV3 Factory contract address prepended with '0xff' and left-aligned.
                      bytes32 private immutable UNI_FF_FACTORY_ADDRESS;
                      /// @dev UniswapV3 pool init code hash.
                      bytes32 private immutable UNI_POOL_INIT_CODE_HASH;
                      /// @dev Minimum size of an encoded swap path:
                      ///      sizeof(address(inputToken) | uint24(fee) | address(outputToken))
                      uint256 private constant SINGLE_HOP_PATH_SIZE = 20 + 3 + 20;
                      /// @dev How many bytes to skip ahead in an encoded path to start at the next hop:
                      ///      sizeof(address(inputToken) | uint24(fee))
                      uint256 private constant PATH_SKIP_HOP_SIZE = 20 + 3;
                      /// @dev The size of the swap callback data.
                      uint256 private constant SWAP_CALLBACK_DATA_SIZE = 128;
                      /// @dev Minimum tick price sqrt ratio.
                      uint160 internal constant MIN_PRICE_SQRT_RATIO = 4295128739;
                      /// @dev Minimum tick price sqrt ratio.
                      uint160 internal constant MAX_PRICE_SQRT_RATIO = 1461446703485210103287273052203988822378723970342;
                      /// @dev Mask of lower 20 bytes.
                      uint256 private constant ADDRESS_MASK = 0x00ffffffffffffffffffffffffffffffffffffffff;
                      /// @dev Mask of lower 3 bytes.
                      uint256 private constant UINT24_MASK = 0xffffff;
                      /// @dev Construct this contract.
                      /// @param weth The WETH contract.
                      /// @param uniFactory The UniswapV3 factory contract.
                      /// @param poolInitCodeHash The UniswapV3 pool init code hash.
                      constructor(IEtherToken weth, address uniFactory, bytes32 poolInitCodeHash) public {
                          WETH = weth;
                          UNI_FF_FACTORY_ADDRESS = bytes32((uint256(0xff) << 248) | (uint256(uniFactory) << 88));
                          UNI_POOL_INIT_CODE_HASH = poolInitCodeHash;
                      }
                      /// @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.sellEthForTokenToUniswapV3.selector);
                          _registerFeatureFunction(this.sellTokenForEthToUniswapV3.selector);
                          _registerFeatureFunction(this.sellTokenForTokenToUniswapV3.selector);
                          _registerFeatureFunction(this._sellTokenForTokenToUniswapV3.selector);
                          _registerFeatureFunction(this._sellHeldTokenForTokenToUniswapV3.selector);
                          _registerFeatureFunction(this.uniswapV3SwapCallback.selector);
                          return LibMigrate.MIGRATE_SUCCESS;
                      }
                      /// @dev Sell attached ETH directly against uniswap v3.
                      /// @param encodedPath Uniswap-encoded path, where the first token is WETH.
                      /// @param recipient The recipient of the bought tokens. Can be zero for sender.
                      /// @param minBuyAmount Minimum amount of the last token in the path to buy.
                      /// @return buyAmount Amount of the last token in the path bought.
                      function sellEthForTokenToUniswapV3(
                          bytes memory encodedPath,
                          uint256 minBuyAmount,
                          address recipient
                      ) public payable override returns (uint256 buyAmount) {
                          // Wrap ETH.
                          WETH.deposit{value: msg.value}();
                          return
                              _swap(
                                  encodedPath,
                                  msg.value,
                                  minBuyAmount,
                                  address(this), // we are payer because we hold the WETH
                                  _normalizeRecipient(recipient)
                              );
                      }
                      /// @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
                      ) public override returns (uint256 buyAmount) {
                          buyAmount = _swap(
                              encodedPath,
                              sellAmount,
                              minBuyAmount,
                              msg.sender,
                              address(this) // we are recipient because we need to unwrap WETH
                          );
                          WETH.withdraw(buyAmount);
                          // Transfer ETH to recipient.
                          (bool success, bytes memory revertData) = _normalizeRecipient(recipient).call{value: buyAmount}("");
                          if (!success) {
                              revertData.rrevert();
                          }
                      }
                      /// @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
                      ) public override returns (uint256 buyAmount) {
                          buyAmount = _swap(encodedPath, sellAmount, minBuyAmount, msg.sender, _normalizeRecipient(recipient));
                      }
                      /// @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
                      ) public override onlySelf returns (uint256 buyAmount) {
                          buyAmount = _swap(encodedPath, sellAmount, minBuyAmount, payer, _normalizeRecipient(recipient, payer));
                      }
                      /// @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
                      ) public override onlySelf returns (uint256 buyAmount) {
                          buyAmount = _swap(encodedPath, sellAmount, minBuyAmount, address(this), _normalizeRecipient(recipient));
                      }
                      /// @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 override {
                          IERC20Token token0;
                          IERC20Token token1;
                          address payer;
                          {
                              uint24 fee;
                              // Decode the data.
                              require(data.length == SWAP_CALLBACK_DATA_SIZE, "UniswapFeature/INVALID_SWAP_CALLBACK_DATA");
                              assembly {
                                  let p := add(36, calldataload(68))
                                  token0 := calldataload(p)
                                  token1 := calldataload(add(p, 32))
                                  fee := calldataload(add(p, 64))
                                  payer := calldataload(add(p, 96))
                              }
                              (token0, token1) = token0 < token1 ? (token0, token1) : (token1, token0);
                              // Only a valid pool contract can call this function.
                              require(
                                  msg.sender == address(_toPool(token0, fee, token1)),
                                  "UniswapV3Feature/INVALID_SWAP_CALLBACK_CALLER"
                              );
                          }
                          // Pay the amount owed to the pool.
                          if (amount0Delta > 0) {
                              _pay(token0, payer, msg.sender, uint256(amount0Delta));
                          } else if (amount1Delta > 0) {
                              _pay(token1, payer, msg.sender, uint256(amount1Delta));
                          } else {
                              revert("UniswapV3Feature/INVALID_SWAP_AMOUNTS");
                          }
                      }
                      // Executes successive swaps along an encoded uniswap path.
                      function _swap(
                          bytes memory encodedPath,
                          uint256 sellAmount,
                          uint256 minBuyAmount,
                          address payer,
                          address recipient
                      ) private returns (uint256 buyAmount) {
                          if (sellAmount != 0) {
                              require(sellAmount <= uint256(type(int256).max), "UniswapV3Feature/SELL_AMOUNT_OVERFLOW");
                              // Perform a swap for each hop in the path.
                              bytes memory swapCallbackData = new bytes(SWAP_CALLBACK_DATA_SIZE);
                              while (true) {
                                  bool isPathMultiHop = _isPathMultiHop(encodedPath);
                                  bool zeroForOne;
                                  IUniswapV3Pool pool;
                                  {
                                      (IERC20Token inputToken, uint24 fee, IERC20Token outputToken) = _decodeFirstPoolInfoFromPath(
                                          encodedPath
                                      );
                                      pool = _toPool(inputToken, fee, outputToken);
                                      zeroForOne = inputToken < outputToken;
                                      _updateSwapCallbackData(swapCallbackData, inputToken, outputToken, fee, payer);
                                  }
                                  (int256 amount0, int256 amount1) = pool.swap(
                                      // Intermediate tokens go to this contract.
                                      isPathMultiHop ? address(this) : recipient,
                                      zeroForOne,
                                      int256(sellAmount),
                                      zeroForOne ? MIN_PRICE_SQRT_RATIO + 1 : MAX_PRICE_SQRT_RATIO - 1,
                                      swapCallbackData
                                  );
                                  {
                                      int256 _buyAmount = -(zeroForOne ? amount1 : amount0);
                                      require(_buyAmount >= 0, "UniswapV3Feature/INVALID_BUY_AMOUNT");
                                      buyAmount = uint256(_buyAmount);
                                  }
                                  if (!isPathMultiHop) {
                                      // Done.
                                      break;
                                  }
                                  // Continue with next hop.
                                  payer = address(this); // Subsequent hops are paid for by us.
                                  sellAmount = buyAmount;
                                  // Skip to next hop along path.
                                  encodedPath = _shiftHopFromPathInPlace(encodedPath);
                              }
                          }
                          require(minBuyAmount <= buyAmount, "UniswapV3Feature/UNDERBOUGHT");
                      }
                      // Pay tokens from `payer` to `to`, using `transferFrom()` if
                      // `payer` != this contract.
                      function _pay(IERC20Token token, address payer, address to, uint256 amount) private {
                          if (payer != address(this)) {
                              _transferERC20TokensFrom(token, payer, to, amount);
                          } else {
                              _transferERC20Tokens(token, to, amount);
                          }
                      }
                      // Update `swapCallbackData` in place with new values.
                      function _updateSwapCallbackData(
                          bytes memory swapCallbackData,
                          IERC20Token inputToken,
                          IERC20Token outputToken,
                          uint24 fee,
                          address payer
                      ) private pure {
                          assembly {
                              let p := add(swapCallbackData, 32)
                              mstore(p, inputToken)
                              mstore(add(p, 32), outputToken)
                              mstore(add(p, 64), and(UINT24_MASK, fee))
                              mstore(add(p, 96), and(ADDRESS_MASK, payer))
                          }
                      }
                      // Compute the pool address given two tokens and a fee.
                      function _toPool(
                          IERC20Token inputToken,
                          uint24 fee,
                          IERC20Token outputToken
                      ) private view returns (IUniswapV3Pool pool) {
                          // address(keccak256(abi.encodePacked(
                          //     hex"ff",
                          //     UNI_FACTORY_ADDRESS,
                          //     keccak256(abi.encode(inputToken, outputToken, fee)),
                          //     UNI_POOL_INIT_CODE_HASH
                          // )))
                          bytes32 ffFactoryAddress = UNI_FF_FACTORY_ADDRESS;
                          bytes32 poolInitCodeHash = UNI_POOL_INIT_CODE_HASH;
                          (IERC20Token token0, IERC20Token token1) = inputToken < outputToken
                              ? (inputToken, outputToken)
                              : (outputToken, inputToken);
                          assembly {
                              let s := mload(0x40)
                              let p := s
                              mstore(p, ffFactoryAddress)
                              p := add(p, 21)
                              // Compute the inner hash in-place
                              mstore(p, token0)
                              mstore(add(p, 32), token1)
                              mstore(add(p, 64), and(UINT24_MASK, fee))
                              mstore(p, keccak256(p, 96))
                              p := add(p, 32)
                              mstore(p, poolInitCodeHash)
                              pool := and(ADDRESS_MASK, keccak256(s, 85))
                          }
                      }
                      // Return whether or not an encoded uniswap path contains more than one hop.
                      function _isPathMultiHop(bytes memory encodedPath) private pure returns (bool isMultiHop) {
                          return encodedPath.length > SINGLE_HOP_PATH_SIZE;
                      }
                      // Return the first input token, output token, and fee of an encoded uniswap path.
                      function _decodeFirstPoolInfoFromPath(
                          bytes memory encodedPath
                      ) private pure returns (IERC20Token inputToken, uint24 fee, IERC20Token outputToken) {
                          require(encodedPath.length >= SINGLE_HOP_PATH_SIZE, "UniswapV3Feature/BAD_PATH_ENCODING");
                          assembly {
                              let p := add(encodedPath, 32)
                              inputToken := shr(96, mload(p))
                              p := add(p, 20)
                              fee := shr(232, mload(p))
                              p := add(p, 3)
                              outputToken := shr(96, mload(p))
                          }
                      }
                      // Skip past the first hop of an encoded uniswap path in-place.
                      function _shiftHopFromPathInPlace(bytes memory encodedPath) private pure returns (bytes memory shiftedEncodedPath) {
                          require(encodedPath.length >= PATH_SKIP_HOP_SIZE, "UniswapV3Feature/BAD_PATH_ENCODING");
                          uint256 shiftSize = PATH_SKIP_HOP_SIZE;
                          uint256 newSize = encodedPath.length - shiftSize;
                          assembly {
                              shiftedEncodedPath := add(encodedPath, shiftSize)
                              mstore(shiftedEncodedPath, newSize)
                          }
                      }
                      // Convert null address values to alternative address.
                      function _normalizeRecipient(
                          address recipient,
                          address alternative
                      ) private pure returns (address payable normalizedRecipient) {
                          return recipient == address(0) ? payable(alternative) : payable(recipient);
                      }
                      // Convert null address values to msg.sender.
                      function _normalizeRecipient(address recipient) private view returns (address payable normalizedRecipient) {
                          return _normalizeRecipient(recipient, msg.sender);
                      }
                  }
                  // 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 interface for a feature contract.
                  interface IFeature {
                      /// @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 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 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;
                  /// @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-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 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/LibSafeMathV06.sol";
                  /// @dev Helpers for moving tokens around.
                  abstract contract FixinTokenSpender {
                      // Mask of the lower 20 bytes of a bytes32.
                      uint256 private constant 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(IERC20Token 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(IERC20Token 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 Transfers some amount of ETH to the given recipient and
                      ///      reverts if the transfer fails.
                      /// @param recipient The recipient of the ETH.
                      /// @param amount The amount of ETH to transfer.
                      function _transferEth(address payable recipient, uint256 amount) internal {
                          if (amount > 0) {
                              (bool success, ) = recipient.call{value: amount}("");
                              require(success, "FixinTokenSpender::_transferEth/TRANSFER_FAILED");
                          }
                      }
                      /// @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(IERC20Token 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 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/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 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 ^0.6.12;
                  interface IUniswapV3Pool {
                      /// @notice Swap token0 for token1, or token1 for token0
                      /// @dev The caller of this method receives a callback in the form of IUniswapV3SwapCallback#uniswapV3SwapCallback
                      /// @param recipient The address to receive the output of the swap
                      /// @param zeroForOne The direction of the swap, true for token0 to token1, false for token1 to token0
                      /// @param amountSpecified The amount of the swap, which implicitly configures the swap as exact input (positive),
                      /// or exact output (negative)
                      /// @param sqrtPriceLimitX96 The Q64.96 sqrt price limit. If zero for one, the price cannot be less than this
                      /// value after the swap. If one for zero, the price cannot be greater than this value after the swap
                      /// @param data Any data to be passed through to the callback
                      /// @return amount0 The delta of the balance of token0 of the pool, exact when negative, minimum when positive
                      /// @return amount1 The delta of the balance of token1 of the pool, exact when negative, minimum when positive
                      function swap(
                          address recipient,
                          bool zeroForOne,
                          int256 amountSpecified,
                          uint160 sqrtPriceLimitX96,
                          bytes calldata data
                      ) external returns (int256 amount0, int256 amount1);
                  }
                  

                  File 6 of 6: FiatTokenV2_2
                  /**
                   * SPDX-License-Identifier: Apache-2.0
                   *
                   * Copyright (c) 2023, Circle Internet Financial, LLC.
                   *
                   * Licensed under the Apache License, Version 2.0 (the "License");
                   * you may not use this file except in compliance with the License.
                   * You may obtain a copy of the License at
                   *
                   * http://www.apache.org/licenses/LICENSE-2.0
                   *
                   * Unless required by applicable law or agreed to in writing, software
                   * distributed under the License is distributed on an "AS IS" BASIS,
                   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                   * See the License for the specific language governing permissions and
                   * limitations under the License.
                   */
                  pragma solidity 0.6.12;
                  import { EIP712Domain } from "./EIP712Domain.sol"; // solhint-disable-line no-unused-import
                  import { Blacklistable } from "../v1/Blacklistable.sol"; // solhint-disable-line no-unused-import
                  import { FiatTokenV1 } from "../v1/FiatTokenV1.sol"; // solhint-disable-line no-unused-import
                  import { FiatTokenV2 } from "./FiatTokenV2.sol"; // solhint-disable-line no-unused-import
                  import { FiatTokenV2_1 } from "./FiatTokenV2_1.sol";
                  import { EIP712 } from "../util/EIP712.sol";
                  // solhint-disable func-name-mixedcase
                  /**
                   * @title FiatToken V2.2
                   * @notice ERC20 Token backed by fiat reserves, version 2.2
                   */
                  contract FiatTokenV2_2 is FiatTokenV2_1 {
                      /**
                       * @notice Initialize v2.2
                       * @param accountsToBlacklist   A list of accounts to migrate from the old blacklist
                       * @param newSymbol             New token symbol
                       * data structure to the new blacklist data structure.
                       */
                      function initializeV2_2(
                          address[] calldata accountsToBlacklist,
                          string calldata newSymbol
                      ) external {
                          // solhint-disable-next-line reason-string
                          require(_initializedVersion == 2);
                          // Update fiat token symbol
                          symbol = newSymbol;
                          // Add previously blacklisted accounts to the new blacklist data structure
                          // and remove them from the old blacklist data structure.
                          for (uint256 i = 0; i < accountsToBlacklist.length; i++) {
                              require(
                                  _deprecatedBlacklisted[accountsToBlacklist[i]],
                                  "FiatTokenV2_2: Blacklisting previously unblacklisted account!"
                              );
                              _blacklist(accountsToBlacklist[i]);
                              delete _deprecatedBlacklisted[accountsToBlacklist[i]];
                          }
                          _blacklist(address(this));
                          delete _deprecatedBlacklisted[address(this)];
                          _initializedVersion = 3;
                      }
                      /**
                       * @dev Internal function to get the current chain id.
                       * @return The current chain id.
                       */
                      function _chainId() internal virtual view returns (uint256) {
                          uint256 chainId;
                          assembly {
                              chainId := chainid()
                          }
                          return chainId;
                      }
                      /**
                       * @inheritdoc EIP712Domain
                       */
                      function _domainSeparator() internal override view returns (bytes32) {
                          return EIP712.makeDomainSeparator(name, "2", _chainId());
                      }
                      /**
                       * @notice Update allowance with a signed permit
                       * @dev EOA wallet signatures should be packed in the order of r, s, v.
                       * @param owner       Token owner's address (Authorizer)
                       * @param spender     Spender's address
                       * @param value       Amount of allowance
                       * @param deadline    The time at which the signature expires (unix time), or max uint256 value to signal no expiration
                       * @param signature   Signature bytes signed by an EOA wallet or a contract wallet
                       */
                      function permit(
                          address owner,
                          address spender,
                          uint256 value,
                          uint256 deadline,
                          bytes memory signature
                      ) external whenNotPaused {
                          _permit(owner, spender, value, deadline, signature);
                      }
                      /**
                       * @notice Execute a transfer with a signed authorization
                       * @dev EOA wallet signatures should be packed in the order of r, s, v.
                       * @param from          Payer's address (Authorizer)
                       * @param to            Payee's address
                       * @param value         Amount to be transferred
                       * @param validAfter    The time after which this is valid (unix time)
                       * @param validBefore   The time before which this is valid (unix time)
                       * @param nonce         Unique nonce
                       * @param signature     Signature bytes signed by an EOA wallet or a contract wallet
                       */
                      function transferWithAuthorization(
                          address from,
                          address to,
                          uint256 value,
                          uint256 validAfter,
                          uint256 validBefore,
                          bytes32 nonce,
                          bytes memory signature
                      ) external whenNotPaused notBlacklisted(from) notBlacklisted(to) {
                          _transferWithAuthorization(
                              from,
                              to,
                              value,
                              validAfter,
                              validBefore,
                              nonce,
                              signature
                          );
                      }
                      /**
                       * @notice Receive a transfer with a signed authorization from the payer
                       * @dev This has an additional check to ensure that the payee's address
                       * matches the caller of this function to prevent front-running attacks.
                       * EOA wallet signatures should be packed in the order of r, s, v.
                       * @param from          Payer's address (Authorizer)
                       * @param to            Payee's address
                       * @param value         Amount to be transferred
                       * @param validAfter    The time after which this is valid (unix time)
                       * @param validBefore   The time before which this is valid (unix time)
                       * @param nonce         Unique nonce
                       * @param signature     Signature bytes signed by an EOA wallet or a contract wallet
                       */
                      function receiveWithAuthorization(
                          address from,
                          address to,
                          uint256 value,
                          uint256 validAfter,
                          uint256 validBefore,
                          bytes32 nonce,
                          bytes memory signature
                      ) external whenNotPaused notBlacklisted(from) notBlacklisted(to) {
                          _receiveWithAuthorization(
                              from,
                              to,
                              value,
                              validAfter,
                              validBefore,
                              nonce,
                              signature
                          );
                      }
                      /**
                       * @notice Attempt to cancel an authorization
                       * @dev Works only if the authorization is not yet used.
                       * EOA wallet signatures should be packed in the order of r, s, v.
                       * @param authorizer    Authorizer's address
                       * @param nonce         Nonce of the authorization
                       * @param signature     Signature bytes signed by an EOA wallet or a contract wallet
                       */
                      function cancelAuthorization(
                          address authorizer,
                          bytes32 nonce,
                          bytes memory signature
                      ) external whenNotPaused {
                          _cancelAuthorization(authorizer, nonce, signature);
                      }
                      /**
                       * @dev Helper method that sets the blacklist state of an account on balanceAndBlacklistStates.
                       * If _shouldBlacklist is true, we apply a (1 << 255) bitmask with an OR operation on the
                       * account's balanceAndBlacklistState. This flips the high bit for the account to 1,
                       * indicating that the account is blacklisted.
                       *
                       * If _shouldBlacklist if false, we reset the account's balanceAndBlacklistStates to their
                       * balances. This clears the high bit for the account, indicating that the account is unblacklisted.
                       * @param _account         The address of the account.
                       * @param _shouldBlacklist True if the account should be blacklisted, false if the account should be unblacklisted.
                       */
                      function _setBlacklistState(address _account, bool _shouldBlacklist)
                          internal
                          override
                      {
                          balanceAndBlacklistStates[_account] = _shouldBlacklist
                              ? balanceAndBlacklistStates[_account] | (1 << 255)
                              : _balanceOf(_account);
                      }
                      /**
                       * @dev Helper method that sets the balance of an account on balanceAndBlacklistStates.
                       * Since balances are stored in the last 255 bits of the balanceAndBlacklistStates value,
                       * we need to ensure that the updated balance does not exceed (2^255 - 1).
                       * Since blacklisted accounts' balances cannot be updated, the method will also
                       * revert if the account is blacklisted
                       * @param _account The address of the account.
                       * @param _balance The new fiat token balance of the account (max: (2^255 - 1)).
                       */
                      function _setBalance(address _account, uint256 _balance) internal override {
                          require(
                              _balance <= ((1 << 255) - 1),
                              "FiatTokenV2_2: Balance exceeds (2^255 - 1)"
                          );
                          require(
                              !_isBlacklisted(_account),
                              "FiatTokenV2_2: Account is blacklisted"
                          );
                          balanceAndBlacklistStates[_account] = _balance;
                      }
                      /**
                       * @inheritdoc Blacklistable
                       */
                      function _isBlacklisted(address _account)
                          internal
                          override
                          view
                          returns (bool)
                      {
                          return balanceAndBlacklistStates[_account] >> 255 == 1;
                      }
                      /**
                       * @dev Helper method to obtain the balance of an account. Since balances
                       * are stored in the last 255 bits of the balanceAndBlacklistStates value,
                       * we apply a ((1 << 255) - 1) bit bitmask with an AND operation on the
                       * balanceAndBlacklistState to obtain the balance.
                       * @param _account  The address of the account.
                       * @return          The fiat token balance of the account.
                       */
                      function _balanceOf(address _account)
                          internal
                          override
                          view
                          returns (uint256)
                      {
                          return balanceAndBlacklistStates[_account] & ((1 << 255) - 1);
                      }
                      /**
                       * @inheritdoc FiatTokenV1
                       */
                      function approve(address spender, uint256 value)
                          external
                          override
                          whenNotPaused
                          returns (bool)
                      {
                          _approve(msg.sender, spender, value);
                          return true;
                      }
                      /**
                       * @inheritdoc FiatTokenV2
                       */
                      function permit(
                          address owner,
                          address spender,
                          uint256 value,
                          uint256 deadline,
                          uint8 v,
                          bytes32 r,
                          bytes32 s
                      ) external override whenNotPaused {
                          _permit(owner, spender, value, deadline, v, r, s);
                      }
                      /**
                       * @inheritdoc FiatTokenV2
                       */
                      function increaseAllowance(address spender, uint256 increment)
                          external
                          override
                          whenNotPaused
                          returns (bool)
                      {
                          _increaseAllowance(msg.sender, spender, increment);
                          return true;
                      }
                      /**
                       * @inheritdoc FiatTokenV2
                       */
                      function decreaseAllowance(address spender, uint256 decrement)
                          external
                          override
                          whenNotPaused
                          returns (bool)
                      {
                          _decreaseAllowance(msg.sender, spender, decrement);
                          return true;
                      }
                  }
                  // SPDX-License-Identifier: MIT
                  pragma solidity >=0.6.2 <0.8.0;
                  /**
                   * @dev Collection of functions related to the address type
                   */
                  library Address {
                      /**
                       * @dev Returns true if `account` is a contract.
                       *
                       * [IMPORTANT]
                       * ====
                       * It is unsafe to assume that an address for which this function returns
                       * false is an externally-owned account (EOA) and not a contract.
                       *
                       * Among others, `isContract` will return false for the following
                       * types of addresses:
                       *
                       *  - an externally-owned account
                       *  - a contract in construction
                       *  - an address where a contract will be created
                       *  - an address where a contract lived, but was destroyed
                       * ====
                       */
                      function isContract(address account) internal view returns (bool) {
                          // This method relies on extcodesize, which returns 0 for contracts in
                          // construction, since the code is only stored at the end of the
                          // constructor execution.
                          uint256 size;
                          // solhint-disable-next-line no-inline-assembly
                          assembly { size := extcodesize(account) }
                          return size > 0;
                      }
                      /**
                       * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
                       * `recipient`, forwarding all available gas and reverting on errors.
                       *
                       * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
                       * of certain opcodes, possibly making contracts go over the 2300 gas limit
                       * imposed by `transfer`, making them unable to receive funds via
                       * `transfer`. {sendValue} removes this limitation.
                       *
                       * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
                       *
                       * IMPORTANT: because control is transferred to `recipient`, care must be
                       * taken to not create reentrancy vulnerabilities. Consider using
                       * {ReentrancyGuard} or the
                       * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
                       */
                      function sendValue(address payable recipient, uint256 amount) internal {
                          require(address(this).balance >= amount, "Address: insufficient balance");
                          // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
                          (bool success, ) = recipient.call{ value: amount }("");
                          require(success, "Address: unable to send value, recipient may have reverted");
                      }
                      /**
                       * @dev Performs a Solidity function call using a low level `call`. A
                       * plain`call` is an unsafe replacement for a function call: use this
                       * function instead.
                       *
                       * If `target` reverts with a revert reason, it is bubbled up by this
                       * function (like regular Solidity function calls).
                       *
                       * Returns the raw returned data. To convert to the expected return value,
                       * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
                       *
                       * Requirements:
                       *
                       * - `target` must be a contract.
                       * - calling `target` with `data` must not revert.
                       *
                       * _Available since v3.1._
                       */
                      function functionCall(address target, bytes memory data) internal returns (bytes memory) {
                        return functionCall(target, data, "Address: low-level call failed");
                      }
                      /**
                       * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
                       * `errorMessage` as a fallback revert reason when `target` reverts.
                       *
                       * _Available since v3.1._
                       */
                      function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
                          return functionCallWithValue(target, data, 0, errorMessage);
                      }
                      /**
                       * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
                       * but also transferring `value` wei to `target`.
                       *
                       * Requirements:
                       *
                       * - the calling contract must have an ETH balance of at least `value`.
                       * - the called Solidity function must be `payable`.
                       *
                       * _Available since v3.1._
                       */
                      function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
                          return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
                      }
                      /**
                       * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
                       * with `errorMessage` as a fallback revert reason when `target` reverts.
                       *
                       * _Available since v3.1._
                       */
                      function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
                          require(address(this).balance >= value, "Address: insufficient balance for call");
                          require(isContract(target), "Address: call to non-contract");
                          // solhint-disable-next-line avoid-low-level-calls
                          (bool success, bytes memory returndata) = target.call{ value: value }(data);
                          return _verifyCallResult(success, returndata, errorMessage);
                      }
                      /**
                       * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
                       * but performing a static call.
                       *
                       * _Available since v3.3._
                       */
                      function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
                          return functionStaticCall(target, data, "Address: low-level static call failed");
                      }
                      /**
                       * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
                       * but performing a static call.
                       *
                       * _Available since v3.3._
                       */
                      function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
                          require(isContract(target), "Address: static call to non-contract");
                          // solhint-disable-next-line avoid-low-level-calls
                          (bool success, bytes memory returndata) = target.staticcall(data);
                          return _verifyCallResult(success, returndata, errorMessage);
                      }
                      /**
                       * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
                       * but performing a delegate call.
                       *
                       * _Available since v3.4._
                       */
                      function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
                          return functionDelegateCall(target, data, "Address: low-level delegate call failed");
                      }
                      /**
                       * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
                       * but performing a delegate call.
                       *
                       * _Available since v3.4._
                       */
                      function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
                          require(isContract(target), "Address: delegate call to non-contract");
                          // solhint-disable-next-line avoid-low-level-calls
                          (bool success, bytes memory returndata) = target.delegatecall(data);
                          return _verifyCallResult(success, returndata, errorMessage);
                      }
                      function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
                          if (success) {
                              return returndata;
                          } else {
                              // Look for revert reason and bubble it up if present
                              if (returndata.length > 0) {
                                  // The easiest way to bubble the revert reason is using memory via assembly
                                  // solhint-disable-next-line no-inline-assembly
                                  assembly {
                                      let returndata_size := mload(returndata)
                                      revert(add(32, returndata), returndata_size)
                                  }
                              } else {
                                  revert(errorMessage);
                              }
                          }
                      }
                  }
                  // SPDX-License-Identifier: MIT
                  pragma solidity >=0.6.0 <0.8.0;
                  import "./IERC20.sol";
                  import "../../math/SafeMath.sol";
                  import "../../utils/Address.sol";
                  /**
                   * @title SafeERC20
                   * @dev Wrappers around ERC20 operations that throw on failure (when the token
                   * contract returns false). Tokens that return no value (and instead revert or
                   * throw on failure) are also supported, non-reverting calls are assumed to be
                   * successful.
                   * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
                   * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
                   */
                  library SafeERC20 {
                      using SafeMath for uint256;
                      using Address for address;
                      function safeTransfer(IERC20 token, address to, uint256 value) internal {
                          _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
                      }
                      function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
                          _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
                      }
                      /**
                       * @dev Deprecated. This function has issues similar to the ones found in
                       * {IERC20-approve}, and its usage is discouraged.
                       *
                       * Whenever possible, use {safeIncreaseAllowance} and
                       * {safeDecreaseAllowance} instead.
                       */
                      function safeApprove(IERC20 token, address spender, uint256 value) internal {
                          // safeApprove should only be called when setting an initial allowance,
                          // or when resetting it to zero. To increase and decrease it, use
                          // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
                          // solhint-disable-next-line max-line-length
                          require((value == 0) || (token.allowance(address(this), spender) == 0),
                              "SafeERC20: approve from non-zero to non-zero allowance"
                          );
                          _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
                      }
                      function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
                          uint256 newAllowance = token.allowance(address(this), spender).add(value);
                          _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
                      }
                      function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
                          uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
                          _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
                      }
                      /**
                       * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
                       * on the return value: the return value is optional (but if data is returned, it must not be false).
                       * @param token The token targeted by the call.
                       * @param data The call data (encoded using abi.encode or one of its variants).
                       */
                      function _callOptionalReturn(IERC20 token, bytes memory data) private {
                          // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
                          // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
                          // the target address contains contract code and also asserts for success in the low-level call.
                          bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
                          if (returndata.length > 0) { // Return data is optional
                              // solhint-disable-next-line max-line-length
                              require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
                          }
                      }
                  }
                  // SPDX-License-Identifier: MIT
                  pragma solidity >=0.6.0 <0.8.0;
                  /**
                   * @dev Interface of the ERC20 standard as defined in the EIP.
                   */
                  interface IERC20 {
                      /**
                       * @dev Returns the amount of tokens in existence.
                       */
                      function totalSupply() external view returns (uint256);
                      /**
                       * @dev Returns the amount of tokens owned by `account`.
                       */
                      function balanceOf(address account) external view returns (uint256);
                      /**
                       * @dev Moves `amount` tokens from the caller's account to `recipient`.
                       *
                       * Returns a boolean value indicating whether the operation succeeded.
                       *
                       * Emits a {Transfer} event.
                       */
                      function transfer(address recipient, uint256 amount) external returns (bool);
                      /**
                       * @dev Returns the remaining number of tokens that `spender` will be
                       * allowed to spend on behalf of `owner` through {transferFrom}. This is
                       * zero by default.
                       *
                       * This value changes when {approve} or {transferFrom} are called.
                       */
                      function allowance(address owner, address spender) external view returns (uint256);
                      /**
                       * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
                       *
                       * Returns a boolean value indicating whether the operation succeeded.
                       *
                       * IMPORTANT: Beware that changing an allowance with this method brings the risk
                       * that someone may use both the old and the new allowance by unfortunate
                       * transaction ordering. One possible solution to mitigate this race
                       * condition is to first reduce the spender's allowance to 0 and set the
                       * desired value afterwards:
                       * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
                       *
                       * Emits an {Approval} event.
                       */
                      function approve(address spender, uint256 amount) external returns (bool);
                      /**
                       * @dev Moves `amount` tokens from `sender` to `recipient` using the
                       * allowance mechanism. `amount` is then deducted from the caller's
                       * allowance.
                       *
                       * Returns a boolean value indicating whether the operation succeeded.
                       *
                       * Emits a {Transfer} event.
                       */
                      function transferFrom(address sender, address recipient, uint256 amount) external returns (bool);
                      /**
                       * @dev Emitted when `value` tokens are moved from one account (`from`) to
                       * another (`to`).
                       *
                       * Note that `value` may be zero.
                       */
                      event Transfer(address indexed from, address indexed to, uint256 value);
                      /**
                       * @dev Emitted when the allowance of a `spender` for an `owner` is set by
                       * a call to {approve}. `value` is the new allowance.
                       */
                      event Approval(address indexed owner, address indexed spender, uint256 value);
                  }
                  // SPDX-License-Identifier: MIT
                  pragma solidity >=0.6.0 <0.8.0;
                  /**
                   * @dev Wrappers over Solidity's arithmetic operations with added overflow
                   * checks.
                   *
                   * Arithmetic operations in Solidity wrap on overflow. This can easily result
                   * in bugs, because programmers usually assume that an overflow raises an
                   * error, which is the standard behavior in high level programming languages.
                   * `SafeMath` restores this intuition by reverting the transaction when an
                   * operation overflows.
                   *
                   * Using this library instead of the unchecked operations eliminates an entire
                   * class of bugs, so it's recommended to use it always.
                   */
                  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) {
                          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) {
                          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) {
                          // 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) {
                          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) {
                          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) {
                          uint256 c = a + b;
                          require(c >= a, "SafeMath: addition overflow");
                          return c;
                      }
                      /**
                       * @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) {
                          require(b <= a, "SafeMath: subtraction overflow");
                          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) {
                          if (a == 0) return 0;
                          uint256 c = a * b;
                          require(c / a == b, "SafeMath: multiplication overflow");
                          return c;
                      }
                      /**
                       * @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. 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) internal pure returns (uint256) {
                          require(b > 0, "SafeMath: division by zero");
                          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) {
                          require(b > 0, "SafeMath: modulo by zero");
                          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) {
                          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.
                       *
                       * CAUTION: This function is deprecated because it requires allocating memory for the error
                       * message unnecessarily. For custom revert reasons use {tryDiv}.
                       *
                       * 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) {
                          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) {
                          require(b > 0, errorMessage);
                          return a % b;
                      }
                  }
                  /**
                   * SPDX-License-Identifier: Apache-2.0
                   *
                   * Copyright (c) 2023, Circle Internet Financial, LLC.
                   *
                   * Licensed under the Apache License, Version 2.0 (the "License");
                   * you may not use this file except in compliance with the License.
                   * You may obtain a copy of the License at
                   *
                   * http://www.apache.org/licenses/LICENSE-2.0
                   *
                   * Unless required by applicable law or agreed to in writing, software
                   * distributed under the License is distributed on an "AS IS" BASIS,
                   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                   * See the License for the specific language governing permissions and
                   * limitations under the License.
                   */
                  pragma solidity 0.6.12;
                  import { FiatTokenV2 } from "./FiatTokenV2.sol";
                  // solhint-disable func-name-mixedcase
                  /**
                   * @title FiatToken V2.1
                   * @notice ERC20 Token backed by fiat reserves, version 2.1
                   */
                  contract FiatTokenV2_1 is FiatTokenV2 {
                      /**
                       * @notice Initialize v2.1
                       * @param lostAndFound  The address to which the locked funds are sent
                       */
                      function initializeV2_1(address lostAndFound) external {
                          // solhint-disable-next-line reason-string
                          require(_initializedVersion == 1);
                          uint256 lockedAmount = _balanceOf(address(this));
                          if (lockedAmount > 0) {
                              _transfer(address(this), lostAndFound, lockedAmount);
                          }
                          _blacklist(address(this));
                          _initializedVersion = 2;
                      }
                      /**
                       * @notice Version string for the EIP712 domain separator
                       * @return Version string
                       */
                      function version() external pure returns (string memory) {
                          return "2";
                      }
                  }
                  /**
                   * SPDX-License-Identifier: Apache-2.0
                   *
                   * Copyright (c) 2023, Circle Internet Financial, LLC.
                   *
                   * Licensed under the Apache License, Version 2.0 (the "License");
                   * you may not use this file except in compliance with the License.
                   * You may obtain a copy of the License at
                   *
                   * http://www.apache.org/licenses/LICENSE-2.0
                   *
                   * Unless required by applicable law or agreed to in writing, software
                   * distributed under the License is distributed on an "AS IS" BASIS,
                   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                   * See the License for the specific language governing permissions and
                   * limitations under the License.
                   */
                  pragma solidity 0.6.12;
                  import { FiatTokenV1_1 } from "../v1.1/FiatTokenV1_1.sol";
                  import { EIP712 } from "../util/EIP712.sol";
                  import { EIP3009 } from "./EIP3009.sol";
                  import { EIP2612 } from "./EIP2612.sol";
                  /**
                   * @title FiatToken V2
                   * @notice ERC20 Token backed by fiat reserves, version 2
                   */
                  contract FiatTokenV2 is FiatTokenV1_1, EIP3009, EIP2612 {
                      uint8 internal _initializedVersion;
                      /**
                       * @notice Initialize v2
                       * @param newName   New token name
                       */
                      function initializeV2(string calldata newName) external {
                          // solhint-disable-next-line reason-string
                          require(initialized && _initializedVersion == 0);
                          name = newName;
                          _DEPRECATED_CACHED_DOMAIN_SEPARATOR = EIP712.makeDomainSeparator(
                              newName,
                              "2"
                          );
                          _initializedVersion = 1;
                      }
                      /**
                       * @notice Increase the allowance by a given increment
                       * @param spender   Spender's address
                       * @param increment Amount of increase in allowance
                       * @return True if successful
                       */
                      function increaseAllowance(address spender, uint256 increment)
                          external
                          virtual
                          whenNotPaused
                          notBlacklisted(msg.sender)
                          notBlacklisted(spender)
                          returns (bool)
                      {
                          _increaseAllowance(msg.sender, spender, increment);
                          return true;
                      }
                      /**
                       * @notice Decrease the allowance by a given decrement
                       * @param spender   Spender's address
                       * @param decrement Amount of decrease in allowance
                       * @return True if successful
                       */
                      function decreaseAllowance(address spender, uint256 decrement)
                          external
                          virtual
                          whenNotPaused
                          notBlacklisted(msg.sender)
                          notBlacklisted(spender)
                          returns (bool)
                      {
                          _decreaseAllowance(msg.sender, spender, decrement);
                          return true;
                      }
                      /**
                       * @notice Execute a transfer with a signed authorization
                       * @param from          Payer's address (Authorizer)
                       * @param to            Payee's address
                       * @param value         Amount to be transferred
                       * @param validAfter    The time after which this is valid (unix time)
                       * @param validBefore   The time before which this is valid (unix time)
                       * @param nonce         Unique nonce
                       * @param v             v of the signature
                       * @param r             r of the signature
                       * @param s             s of the signature
                       */
                      function transferWithAuthorization(
                          address from,
                          address to,
                          uint256 value,
                          uint256 validAfter,
                          uint256 validBefore,
                          bytes32 nonce,
                          uint8 v,
                          bytes32 r,
                          bytes32 s
                      ) external whenNotPaused notBlacklisted(from) notBlacklisted(to) {
                          _transferWithAuthorization(
                              from,
                              to,
                              value,
                              validAfter,
                              validBefore,
                              nonce,
                              v,
                              r,
                              s
                          );
                      }
                      /**
                       * @notice Receive a transfer with a signed authorization from the payer
                       * @dev This has an additional check to ensure that the payee's address
                       * matches the caller of this function to prevent front-running attacks.
                       * @param from          Payer's address (Authorizer)
                       * @param to            Payee's address
                       * @param value         Amount to be transferred
                       * @param validAfter    The time after which this is valid (unix time)
                       * @param validBefore   The time before which this is valid (unix time)
                       * @param nonce         Unique nonce
                       * @param v             v of the signature
                       * @param r             r of the signature
                       * @param s             s of the signature
                       */
                      function receiveWithAuthorization(
                          address from,
                          address to,
                          uint256 value,
                          uint256 validAfter,
                          uint256 validBefore,
                          bytes32 nonce,
                          uint8 v,
                          bytes32 r,
                          bytes32 s
                      ) external whenNotPaused notBlacklisted(from) notBlacklisted(to) {
                          _receiveWithAuthorization(
                              from,
                              to,
                              value,
                              validAfter,
                              validBefore,
                              nonce,
                              v,
                              r,
                              s
                          );
                      }
                      /**
                       * @notice Attempt to cancel an authorization
                       * @dev Works only if the authorization is not yet used.
                       * @param authorizer    Authorizer's address
                       * @param nonce         Nonce of the authorization
                       * @param v             v of the signature
                       * @param r             r of the signature
                       * @param s             s of the signature
                       */
                      function cancelAuthorization(
                          address authorizer,
                          bytes32 nonce,
                          uint8 v,
                          bytes32 r,
                          bytes32 s
                      ) external whenNotPaused {
                          _cancelAuthorization(authorizer, nonce, v, r, s);
                      }
                      /**
                       * @notice Update allowance with a signed permit
                       * @param owner       Token owner's address (Authorizer)
                       * @param spender     Spender's address
                       * @param value       Amount of allowance
                       * @param deadline    The time at which the signature expires (unix time), or max uint256 value to signal no expiration
                       * @param v           v of the signature
                       * @param r           r of the signature
                       * @param s           s of the signature
                       */
                      function permit(
                          address owner,
                          address spender,
                          uint256 value,
                          uint256 deadline,
                          uint8 v,
                          bytes32 r,
                          bytes32 s
                      )
                          external
                          virtual
                          whenNotPaused
                          notBlacklisted(owner)
                          notBlacklisted(spender)
                      {
                          _permit(owner, spender, value, deadline, v, r, s);
                      }
                      /**
                       * @dev Internal function to increase the allowance by a given increment
                       * @param owner     Token owner's address
                       * @param spender   Spender's address
                       * @param increment Amount of increase
                       */
                      function _increaseAllowance(
                          address owner,
                          address spender,
                          uint256 increment
                      ) internal override {
                          _approve(owner, spender, allowed[owner][spender].add(increment));
                      }
                      /**
                       * @dev Internal function to decrease the allowance by a given decrement
                       * @param owner     Token owner's address
                       * @param spender   Spender's address
                       * @param decrement Amount of decrease
                       */
                      function _decreaseAllowance(
                          address owner,
                          address spender,
                          uint256 decrement
                      ) internal override {
                          _approve(
                              owner,
                              spender,
                              allowed[owner][spender].sub(
                                  decrement,
                                  "ERC20: decreased allowance below zero"
                              )
                          );
                      }
                  }
                  /**
                   * SPDX-License-Identifier: Apache-2.0
                   *
                   * Copyright (c) 2023, Circle Internet Financial, LLC.
                   *
                   * Licensed under the Apache License, Version 2.0 (the "License");
                   * you may not use this file except in compliance with the License.
                   * You may obtain a copy of the License at
                   *
                   * http://www.apache.org/licenses/LICENSE-2.0
                   *
                   * Unless required by applicable law or agreed to in writing, software
                   * distributed under the License is distributed on an "AS IS" BASIS,
                   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                   * See the License for the specific language governing permissions and
                   * limitations under the License.
                   */
                  pragma solidity 0.6.12;
                  // solhint-disable func-name-mixedcase
                  /**
                   * @title EIP712 Domain
                   */
                  contract EIP712Domain {
                      // was originally DOMAIN_SEPARATOR
                      // but that has been moved to a method so we can override it in V2_2+
                      bytes32 internal _DEPRECATED_CACHED_DOMAIN_SEPARATOR;
                      /**
                       * @notice Get the EIP712 Domain Separator.
                       * @return The bytes32 EIP712 domain separator.
                       */
                      function DOMAIN_SEPARATOR() external view returns (bytes32) {
                          return _domainSeparator();
                      }
                      /**
                       * @dev Internal method to get the EIP712 Domain Separator.
                       * @return The bytes32 EIP712 domain separator.
                       */
                      function _domainSeparator() internal virtual view returns (bytes32) {
                          return _DEPRECATED_CACHED_DOMAIN_SEPARATOR;
                      }
                  }
                  /**
                   * SPDX-License-Identifier: Apache-2.0
                   *
                   * Copyright (c) 2023, Circle Internet Financial, LLC.
                   *
                   * Licensed under the Apache License, Version 2.0 (the "License");
                   * you may not use this file except in compliance with the License.
                   * You may obtain a copy of the License at
                   *
                   * http://www.apache.org/licenses/LICENSE-2.0
                   *
                   * Unless required by applicable law or agreed to in writing, software
                   * distributed under the License is distributed on an "AS IS" BASIS,
                   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                   * See the License for the specific language governing permissions and
                   * limitations under the License.
                   */
                  pragma solidity 0.6.12;
                  import { AbstractFiatTokenV2 } from "./AbstractFiatTokenV2.sol";
                  import { EIP712Domain } from "./EIP712Domain.sol";
                  import { SignatureChecker } from "../util/SignatureChecker.sol";
                  import { MessageHashUtils } from "../util/MessageHashUtils.sol";
                  /**
                   * @title EIP-3009
                   * @notice Provide internal implementation for gas-abstracted transfers
                   * @dev Contracts that inherit from this must wrap these with publicly
                   * accessible functions, optionally adding modifiers where necessary
                   */
                  abstract contract EIP3009 is AbstractFiatTokenV2, EIP712Domain {
                      // keccak256("TransferWithAuthorization(address from,address to,uint256 value,uint256 validAfter,uint256 validBefore,bytes32 nonce)")
                      bytes32
                          public constant TRANSFER_WITH_AUTHORIZATION_TYPEHASH = 0x7c7c6cdb67a18743f49ec6fa9b35f50d52ed05cbed4cc592e13b44501c1a2267;
                      // keccak256("ReceiveWithAuthorization(address from,address to,uint256 value,uint256 validAfter,uint256 validBefore,bytes32 nonce)")
                      bytes32
                          public constant RECEIVE_WITH_AUTHORIZATION_TYPEHASH = 0xd099cc98ef71107a616c4f0f941f04c322d8e254fe26b3c6668db87aae413de8;
                      // keccak256("CancelAuthorization(address authorizer,bytes32 nonce)")
                      bytes32
                          public constant CANCEL_AUTHORIZATION_TYPEHASH = 0x158b0a9edf7a828aad02f63cd515c68ef2f50ba807396f6d12842833a1597429;
                      /**
                       * @dev authorizer address => nonce => bool (true if nonce is used)
                       */
                      mapping(address => mapping(bytes32 => bool)) private _authorizationStates;
                      event AuthorizationUsed(address indexed authorizer, bytes32 indexed nonce);
                      event AuthorizationCanceled(
                          address indexed authorizer,
                          bytes32 indexed nonce
                      );
                      /**
                       * @notice Returns the state of an authorization
                       * @dev Nonces are randomly generated 32-byte data unique to the
                       * authorizer's address
                       * @param authorizer    Authorizer's address
                       * @param nonce         Nonce of the authorization
                       * @return True if the nonce is used
                       */
                      function authorizationState(address authorizer, bytes32 nonce)
                          external
                          view
                          returns (bool)
                      {
                          return _authorizationStates[authorizer][nonce];
                      }
                      /**
                       * @notice Execute a transfer with a signed authorization
                       * @param from          Payer's address (Authorizer)
                       * @param to            Payee's address
                       * @param value         Amount to be transferred
                       * @param validAfter    The time after which this is valid (unix time)
                       * @param validBefore   The time before which this is valid (unix time)
                       * @param nonce         Unique nonce
                       * @param v             v of the signature
                       * @param r             r of the signature
                       * @param s             s of the signature
                       */
                      function _transferWithAuthorization(
                          address from,
                          address to,
                          uint256 value,
                          uint256 validAfter,
                          uint256 validBefore,
                          bytes32 nonce,
                          uint8 v,
                          bytes32 r,
                          bytes32 s
                      ) internal {
                          _transferWithAuthorization(
                              from,
                              to,
                              value,
                              validAfter,
                              validBefore,
                              nonce,
                              abi.encodePacked(r, s, v)
                          );
                      }
                      /**
                       * @notice Execute a transfer with a signed authorization
                       * @dev EOA wallet signatures should be packed in the order of r, s, v.
                       * @param from          Payer's address (Authorizer)
                       * @param to            Payee's address
                       * @param value         Amount to be transferred
                       * @param validAfter    The time after which this is valid (unix time)
                       * @param validBefore   The time before which this is valid (unix time)
                       * @param nonce         Unique nonce
                       * @param signature     Signature byte array produced by an EOA wallet or a contract wallet
                       */
                      function _transferWithAuthorization(
                          address from,
                          address to,
                          uint256 value,
                          uint256 validAfter,
                          uint256 validBefore,
                          bytes32 nonce,
                          bytes memory signature
                      ) internal {
                          _requireValidAuthorization(from, nonce, validAfter, validBefore);
                          _requireValidSignature(
                              from,
                              keccak256(
                                  abi.encode(
                                      TRANSFER_WITH_AUTHORIZATION_TYPEHASH,
                                      from,
                                      to,
                                      value,
                                      validAfter,
                                      validBefore,
                                      nonce
                                  )
                              ),
                              signature
                          );
                          _markAuthorizationAsUsed(from, nonce);
                          _transfer(from, to, value);
                      }
                      /**
                       * @notice Receive a transfer with a signed authorization from the payer
                       * @dev This has an additional check to ensure that the payee's address
                       * matches the caller of this function to prevent front-running attacks.
                       * @param from          Payer's address (Authorizer)
                       * @param to            Payee's address
                       * @param value         Amount to be transferred
                       * @param validAfter    The time after which this is valid (unix time)
                       * @param validBefore   The time before which this is valid (unix time)
                       * @param nonce         Unique nonce
                       * @param v             v of the signature
                       * @param r             r of the signature
                       * @param s             s of the signature
                       */
                      function _receiveWithAuthorization(
                          address from,
                          address to,
                          uint256 value,
                          uint256 validAfter,
                          uint256 validBefore,
                          bytes32 nonce,
                          uint8 v,
                          bytes32 r,
                          bytes32 s
                      ) internal {
                          _receiveWithAuthorization(
                              from,
                              to,
                              value,
                              validAfter,
                              validBefore,
                              nonce,
                              abi.encodePacked(r, s, v)
                          );
                      }
                      /**
                       * @notice Receive a transfer with a signed authorization from the payer
                       * @dev This has an additional check to ensure that the payee's address
                       * matches the caller of this function to prevent front-running attacks.
                       * EOA wallet signatures should be packed in the order of r, s, v.
                       * @param from          Payer's address (Authorizer)
                       * @param to            Payee's address
                       * @param value         Amount to be transferred
                       * @param validAfter    The time after which this is valid (unix time)
                       * @param validBefore   The time before which this is valid (unix time)
                       * @param nonce         Unique nonce
                       * @param signature     Signature byte array produced by an EOA wallet or a contract wallet
                       */
                      function _receiveWithAuthorization(
                          address from,
                          address to,
                          uint256 value,
                          uint256 validAfter,
                          uint256 validBefore,
                          bytes32 nonce,
                          bytes memory signature
                      ) internal {
                          require(to == msg.sender, "FiatTokenV2: caller must be the payee");
                          _requireValidAuthorization(from, nonce, validAfter, validBefore);
                          _requireValidSignature(
                              from,
                              keccak256(
                                  abi.encode(
                                      RECEIVE_WITH_AUTHORIZATION_TYPEHASH,
                                      from,
                                      to,
                                      value,
                                      validAfter,
                                      validBefore,
                                      nonce
                                  )
                              ),
                              signature
                          );
                          _markAuthorizationAsUsed(from, nonce);
                          _transfer(from, to, value);
                      }
                      /**
                       * @notice Attempt to cancel an authorization
                       * @param authorizer    Authorizer's address
                       * @param nonce         Nonce of the authorization
                       * @param v             v of the signature
                       * @param r             r of the signature
                       * @param s             s of the signature
                       */
                      function _cancelAuthorization(
                          address authorizer,
                          bytes32 nonce,
                          uint8 v,
                          bytes32 r,
                          bytes32 s
                      ) internal {
                          _cancelAuthorization(authorizer, nonce, abi.encodePacked(r, s, v));
                      }
                      /**
                       * @notice Attempt to cancel an authorization
                       * @dev EOA wallet signatures should be packed in the order of r, s, v.
                       * @param authorizer    Authorizer's address
                       * @param nonce         Nonce of the authorization
                       * @param signature     Signature byte array produced by an EOA wallet or a contract wallet
                       */
                      function _cancelAuthorization(
                          address authorizer,
                          bytes32 nonce,
                          bytes memory signature
                      ) internal {
                          _requireUnusedAuthorization(authorizer, nonce);
                          _requireValidSignature(
                              authorizer,
                              keccak256(
                                  abi.encode(CANCEL_AUTHORIZATION_TYPEHASH, authorizer, nonce)
                              ),
                              signature
                          );
                          _authorizationStates[authorizer][nonce] = true;
                          emit AuthorizationCanceled(authorizer, nonce);
                      }
                      /**
                       * @notice Validates that signature against input data struct
                       * @param signer        Signer's address
                       * @param dataHash      Hash of encoded data struct
                       * @param signature     Signature byte array produced by an EOA wallet or a contract wallet
                       */
                      function _requireValidSignature(
                          address signer,
                          bytes32 dataHash,
                          bytes memory signature
                      ) private view {
                          require(
                              SignatureChecker.isValidSignatureNow(
                                  signer,
                                  MessageHashUtils.toTypedDataHash(_domainSeparator(), dataHash),
                                  signature
                              ),
                              "FiatTokenV2: invalid signature"
                          );
                      }
                      /**
                       * @notice Check that an authorization is unused
                       * @param authorizer    Authorizer's address
                       * @param nonce         Nonce of the authorization
                       */
                      function _requireUnusedAuthorization(address authorizer, bytes32 nonce)
                          private
                          view
                      {
                          require(
                              !_authorizationStates[authorizer][nonce],
                              "FiatTokenV2: authorization is used or canceled"
                          );
                      }
                      /**
                       * @notice Check that authorization is valid
                       * @param authorizer    Authorizer's address
                       * @param nonce         Nonce of the authorization
                       * @param validAfter    The time after which this is valid (unix time)
                       * @param validBefore   The time before which this is valid (unix time)
                       */
                      function _requireValidAuthorization(
                          address authorizer,
                          bytes32 nonce,
                          uint256 validAfter,
                          uint256 validBefore
                      ) private view {
                          require(
                              now > validAfter,
                              "FiatTokenV2: authorization is not yet valid"
                          );
                          require(now < validBefore, "FiatTokenV2: authorization is expired");
                          _requireUnusedAuthorization(authorizer, nonce);
                      }
                      /**
                       * @notice Mark an authorization as used
                       * @param authorizer    Authorizer's address
                       * @param nonce         Nonce of the authorization
                       */
                      function _markAuthorizationAsUsed(address authorizer, bytes32 nonce)
                          private
                      {
                          _authorizationStates[authorizer][nonce] = true;
                          emit AuthorizationUsed(authorizer, nonce);
                      }
                  }
                  /**
                   * SPDX-License-Identifier: Apache-2.0
                   *
                   * Copyright (c) 2023, Circle Internet Financial, LLC.
                   *
                   * Licensed under the Apache License, Version 2.0 (the "License");
                   * you may not use this file except in compliance with the License.
                   * You may obtain a copy of the License at
                   *
                   * http://www.apache.org/licenses/LICENSE-2.0
                   *
                   * Unless required by applicable law or agreed to in writing, software
                   * distributed under the License is distributed on an "AS IS" BASIS,
                   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                   * See the License for the specific language governing permissions and
                   * limitations under the License.
                   */
                  pragma solidity 0.6.12;
                  import { AbstractFiatTokenV2 } from "./AbstractFiatTokenV2.sol";
                  import { EIP712Domain } from "./EIP712Domain.sol";
                  import { MessageHashUtils } from "../util/MessageHashUtils.sol";
                  import { SignatureChecker } from "../util/SignatureChecker.sol";
                  /**
                   * @title EIP-2612
                   * @notice Provide internal implementation for gas-abstracted approvals
                   */
                  abstract contract EIP2612 is AbstractFiatTokenV2, EIP712Domain {
                      // keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)")
                      bytes32
                          public constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
                      mapping(address => uint256) private _permitNonces;
                      /**
                       * @notice Nonces for permit
                       * @param owner Token owner's address (Authorizer)
                       * @return Next nonce
                       */
                      function nonces(address owner) external view returns (uint256) {
                          return _permitNonces[owner];
                      }
                      /**
                       * @notice Verify a signed approval permit and execute if valid
                       * @param owner     Token owner's address (Authorizer)
                       * @param spender   Spender's address
                       * @param value     Amount of allowance
                       * @param deadline  The time at which the signature expires (unix time), or max uint256 value to signal no expiration
                       * @param v         v of the signature
                       * @param r         r of the signature
                       * @param s         s of the signature
                       */
                      function _permit(
                          address owner,
                          address spender,
                          uint256 value,
                          uint256 deadline,
                          uint8 v,
                          bytes32 r,
                          bytes32 s
                      ) internal {
                          _permit(owner, spender, value, deadline, abi.encodePacked(r, s, v));
                      }
                      /**
                       * @notice Verify a signed approval permit and execute if valid
                       * @dev EOA wallet signatures should be packed in the order of r, s, v.
                       * @param owner      Token owner's address (Authorizer)
                       * @param spender    Spender's address
                       * @param value      Amount of allowance
                       * @param deadline   The time at which the signature expires (unix time), or max uint256 value to signal no expiration
                       * @param signature  Signature byte array signed by an EOA wallet or a contract wallet
                       */
                      function _permit(
                          address owner,
                          address spender,
                          uint256 value,
                          uint256 deadline,
                          bytes memory signature
                      ) internal {
                          require(
                              deadline == type(uint256).max || deadline >= now,
                              "FiatTokenV2: permit is expired"
                          );
                          bytes32 typedDataHash = MessageHashUtils.toTypedDataHash(
                              _domainSeparator(),
                              keccak256(
                                  abi.encode(
                                      PERMIT_TYPEHASH,
                                      owner,
                                      spender,
                                      value,
                                      _permitNonces[owner]++,
                                      deadline
                                  )
                              )
                          );
                          require(
                              SignatureChecker.isValidSignatureNow(
                                  owner,
                                  typedDataHash,
                                  signature
                              ),
                              "EIP2612: invalid signature"
                          );
                          _approve(owner, spender, value);
                      }
                  }
                  /**
                   * SPDX-License-Identifier: Apache-2.0
                   *
                   * Copyright (c) 2023, Circle Internet Financial, LLC.
                   *
                   * Licensed under the Apache License, Version 2.0 (the "License");
                   * you may not use this file except in compliance with the License.
                   * You may obtain a copy of the License at
                   *
                   * http://www.apache.org/licenses/LICENSE-2.0
                   *
                   * Unless required by applicable law or agreed to in writing, software
                   * distributed under the License is distributed on an "AS IS" BASIS,
                   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                   * See the License for the specific language governing permissions and
                   * limitations under the License.
                   */
                  pragma solidity 0.6.12;
                  import { AbstractFiatTokenV1 } from "../v1/AbstractFiatTokenV1.sol";
                  abstract contract AbstractFiatTokenV2 is AbstractFiatTokenV1 {
                      function _increaseAllowance(
                          address owner,
                          address spender,
                          uint256 increment
                      ) internal virtual;
                      function _decreaseAllowance(
                          address owner,
                          address spender,
                          uint256 decrement
                      ) internal virtual;
                  }
                  /**
                   * SPDX-License-Identifier: MIT
                   *
                   * Copyright (c) 2016 Smart Contract Solutions, Inc.
                   * Copyright (c) 2018-2020 CENTRE SECZ
                   *
                   * Permission is hereby granted, free of charge, to any person obtaining a copy
                   * of this software and associated documentation files (the "Software"), to deal
                   * in the Software without restriction, including without limitation the rights
                   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
                   * copies of the Software, and to permit persons to whom the Software is
                   * furnished to do so, subject to the following conditions:
                   *
                   * The above copyright notice and this permission notice shall be included in
                   * copies or substantial portions of the Software.
                   *
                   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
                   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
                   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
                   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
                   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
                   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
                   * SOFTWARE.
                   */
                  pragma solidity 0.6.12;
                  import { Ownable } from "./Ownable.sol";
                  /**
                   * @notice Base contract which allows children to implement an emergency stop
                   * mechanism
                   * @dev Forked from https://github.com/OpenZeppelin/openzeppelin-contracts/blob/feb665136c0dae9912e08397c1a21c4af3651ef3/contracts/lifecycle/Pausable.sol
                   * Modifications:
                   * 1. Added pauser role, switched pause/unpause to be onlyPauser (6/14/2018)
                   * 2. Removed whenNotPause/whenPaused from pause/unpause (6/14/2018)
                   * 3. Removed whenPaused (6/14/2018)
                   * 4. Switches ownable library to use ZeppelinOS (7/12/18)
                   * 5. Remove constructor (7/13/18)
                   * 6. Reformat, conform to Solidity 0.6 syntax and add error messages (5/13/20)
                   * 7. Make public functions external (5/27/20)
                   */
                  contract Pausable is Ownable {
                      event Pause();
                      event Unpause();
                      event PauserChanged(address indexed newAddress);
                      address public pauser;
                      bool public paused = false;
                      /**
                       * @dev Modifier to make a function callable only when the contract is not paused.
                       */
                      modifier whenNotPaused() {
                          require(!paused, "Pausable: paused");
                          _;
                      }
                      /**
                       * @dev throws if called by any account other than the pauser
                       */
                      modifier onlyPauser() {
                          require(msg.sender == pauser, "Pausable: caller is not the pauser");
                          _;
                      }
                      /**
                       * @dev called by the owner to pause, triggers stopped state
                       */
                      function pause() external onlyPauser {
                          paused = true;
                          emit Pause();
                      }
                      /**
                       * @dev called by the owner to unpause, returns to normal state
                       */
                      function unpause() external onlyPauser {
                          paused = false;
                          emit Unpause();
                      }
                      /**
                       * @notice Updates the pauser address.
                       * @param _newPauser The address of the new pauser.
                       */
                      function updatePauser(address _newPauser) external onlyOwner {
                          require(
                              _newPauser != address(0),
                              "Pausable: new pauser is the zero address"
                          );
                          pauser = _newPauser;
                          emit PauserChanged(pauser);
                      }
                  }
                  /**
                   * SPDX-License-Identifier: MIT
                   *
                   * Copyright (c) 2018 zOS Global Limited.
                   * Copyright (c) 2018-2020 CENTRE SECZ
                   *
                   * Permission is hereby granted, free of charge, to any person obtaining a copy
                   * of this software and associated documentation files (the "Software"), to deal
                   * in the Software without restriction, including without limitation the rights
                   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
                   * copies of the Software, and to permit persons to whom the Software is
                   * furnished to do so, subject to the following conditions:
                   *
                   * The above copyright notice and this permission notice shall be included in
                   * copies or substantial portions of the Software.
                   *
                   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
                   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
                   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
                   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
                   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
                   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
                   * SOFTWARE.
                   */
                  pragma solidity 0.6.12;
                  /**
                   * @notice The Ownable contract has an owner address, and provides basic
                   * authorization control functions
                   * @dev Forked from https://github.com/OpenZeppelin/openzeppelin-labs/blob/3887ab77b8adafba4a26ace002f3a684c1a3388b/upgradeability_ownership/contracts/ownership/Ownable.sol
                   * Modifications:
                   * 1. Consolidate OwnableStorage into this contract (7/13/18)
                   * 2. Reformat, conform to Solidity 0.6 syntax, and add error messages (5/13/20)
                   * 3. Make public functions external (5/27/20)
                   */
                  contract Ownable {
                      // Owner of the contract
                      address private _owner;
                      /**
                       * @dev Event to show ownership has been transferred
                       * @param previousOwner representing the address of the previous owner
                       * @param newOwner representing the address of the new owner
                       */
                      event OwnershipTransferred(address previousOwner, address newOwner);
                      /**
                       * @dev The constructor sets the original owner of the contract to the sender account.
                       */
                      constructor() public {
                          setOwner(msg.sender);
                      }
                      /**
                       * @dev Tells the address of the owner
                       * @return the address of the owner
                       */
                      function owner() external view returns (address) {
                          return _owner;
                      }
                      /**
                       * @dev Sets a new owner address
                       */
                      function setOwner(address newOwner) internal {
                          _owner = newOwner;
                      }
                      /**
                       * @dev Throws if called by any account other than the owner.
                       */
                      modifier onlyOwner() {
                          require(msg.sender == _owner, "Ownable: caller is not the owner");
                          _;
                      }
                      /**
                       * @dev Allows the current owner to transfer control of the contract to a newOwner.
                       * @param newOwner The address to transfer ownership to.
                       */
                      function transferOwnership(address newOwner) external onlyOwner {
                          require(
                              newOwner != address(0),
                              "Ownable: new owner is the zero address"
                          );
                          emit OwnershipTransferred(_owner, newOwner);
                          setOwner(newOwner);
                      }
                  }
                  /**
                   * SPDX-License-Identifier: Apache-2.0
                   *
                   * Copyright (c) 2023, Circle Internet Financial, LLC.
                   *
                   * Licensed under the Apache License, Version 2.0 (the "License");
                   * you may not use this file except in compliance with the License.
                   * You may obtain a copy of the License at
                   *
                   * http://www.apache.org/licenses/LICENSE-2.0
                   *
                   * Unless required by applicable law or agreed to in writing, software
                   * distributed under the License is distributed on an "AS IS" BASIS,
                   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                   * See the License for the specific language governing permissions and
                   * limitations under the License.
                   */
                  pragma solidity 0.6.12;
                  import { SafeMath } from "@openzeppelin/contracts/math/SafeMath.sol";
                  import { AbstractFiatTokenV1 } from "./AbstractFiatTokenV1.sol";
                  import { Ownable } from "./Ownable.sol";
                  import { Pausable } from "./Pausable.sol";
                  import { Blacklistable } from "./Blacklistable.sol";
                  /**
                   * @title FiatToken
                   * @dev ERC20 Token backed by fiat reserves
                   */
                  contract FiatTokenV1 is AbstractFiatTokenV1, Ownable, Pausable, Blacklistable {
                      using SafeMath for uint256;
                      string public name;
                      string public symbol;
                      uint8 public decimals;
                      string public currency;
                      address public masterMinter;
                      bool internal initialized;
                      /// @dev A mapping that stores the balance and blacklist states for a given address.
                      /// The first bit defines whether the address is blacklisted (1 if blacklisted, 0 otherwise).
                      /// The last 255 bits define the balance for the address.
                      mapping(address => uint256) internal balanceAndBlacklistStates;
                      mapping(address => mapping(address => uint256)) internal allowed;
                      uint256 internal totalSupply_ = 0;
                      mapping(address => bool) internal minters;
                      mapping(address => uint256) internal minterAllowed;
                      event Mint(address indexed minter, address indexed to, uint256 amount);
                      event Burn(address indexed burner, uint256 amount);
                      event MinterConfigured(address indexed minter, uint256 minterAllowedAmount);
                      event MinterRemoved(address indexed oldMinter);
                      event MasterMinterChanged(address indexed newMasterMinter);
                      /**
                       * @notice Initializes the fiat token contract.
                       * @param tokenName       The name of the fiat token.
                       * @param tokenSymbol     The symbol of the fiat token.
                       * @param tokenCurrency   The fiat currency that the token represents.
                       * @param tokenDecimals   The number of decimals that the token uses.
                       * @param newMasterMinter The masterMinter address for the fiat token.
                       * @param newPauser       The pauser address for the fiat token.
                       * @param newBlacklister  The blacklister address for the fiat token.
                       * @param newOwner        The owner of the fiat token.
                       */
                      function initialize(
                          string memory tokenName,
                          string memory tokenSymbol,
                          string memory tokenCurrency,
                          uint8 tokenDecimals,
                          address newMasterMinter,
                          address newPauser,
                          address newBlacklister,
                          address newOwner
                      ) public {
                          require(!initialized, "FiatToken: contract is already initialized");
                          require(
                              newMasterMinter != address(0),
                              "FiatToken: new masterMinter is the zero address"
                          );
                          require(
                              newPauser != address(0),
                              "FiatToken: new pauser is the zero address"
                          );
                          require(
                              newBlacklister != address(0),
                              "FiatToken: new blacklister is the zero address"
                          );
                          require(
                              newOwner != address(0),
                              "FiatToken: new owner is the zero address"
                          );
                          name = tokenName;
                          symbol = tokenSymbol;
                          currency = tokenCurrency;
                          decimals = tokenDecimals;
                          masterMinter = newMasterMinter;
                          pauser = newPauser;
                          blacklister = newBlacklister;
                          setOwner(newOwner);
                          initialized = true;
                      }
                      /**
                       * @dev Throws if called by any account other than a minter.
                       */
                      modifier onlyMinters() {
                          require(minters[msg.sender], "FiatToken: caller is not a minter");
                          _;
                      }
                      /**
                       * @notice Mints fiat tokens to an address.
                       * @param _to The address that will receive the minted tokens.
                       * @param _amount The amount of tokens to mint. Must be less than or equal
                       * to the minterAllowance of the caller.
                       * @return True if the operation was successful.
                       */
                      function mint(address _to, uint256 _amount)
                          external
                          whenNotPaused
                          onlyMinters
                          notBlacklisted(msg.sender)
                          notBlacklisted(_to)
                          returns (bool)
                      {
                          require(_to != address(0), "FiatToken: mint to the zero address");
                          require(_amount > 0, "FiatToken: mint amount not greater than 0");
                          uint256 mintingAllowedAmount = minterAllowed[msg.sender];
                          require(
                              _amount <= mintingAllowedAmount,
                              "FiatToken: mint amount exceeds minterAllowance"
                          );
                          totalSupply_ = totalSupply_.add(_amount);
                          _setBalance(_to, _balanceOf(_to).add(_amount));
                          minterAllowed[msg.sender] = mintingAllowedAmount.sub(_amount);
                          emit Mint(msg.sender, _to, _amount);
                          emit Transfer(address(0), _to, _amount);
                          return true;
                      }
                      /**
                       * @dev Throws if called by any account other than the masterMinter
                       */
                      modifier onlyMasterMinter() {
                          require(
                              msg.sender == masterMinter,
                              "FiatToken: caller is not the masterMinter"
                          );
                          _;
                      }
                      /**
                       * @notice Gets the minter allowance for an account.
                       * @param minter The address to check.
                       * @return The remaining minter allowance for the account.
                       */
                      function minterAllowance(address minter) external view returns (uint256) {
                          return minterAllowed[minter];
                      }
                      /**
                       * @notice Checks if an account is a minter.
                       * @param account The address to check.
                       * @return True if the account is a minter, false if the account is not a minter.
                       */
                      function isMinter(address account) external view returns (bool) {
                          return minters[account];
                      }
                      /**
                       * @notice Gets the remaining amount of fiat tokens a spender is allowed to transfer on
                       * behalf of the token owner.
                       * @param owner   The token owner's address.
                       * @param spender The spender's address.
                       * @return The remaining allowance.
                       */
                      function allowance(address owner, address spender)
                          external
                          override
                          view
                          returns (uint256)
                      {
                          return allowed[owner][spender];
                      }
                      /**
                       * @notice Gets the totalSupply of the fiat token.
                       * @return The totalSupply of the fiat token.
                       */
                      function totalSupply() external override view returns (uint256) {
                          return totalSupply_;
                      }
                      /**
                       * @notice Gets the fiat token balance of an account.
                       * @param account  The address to check.
                       * @return balance The fiat token balance of the account.
                       */
                      function balanceOf(address account)
                          external
                          override
                          view
                          returns (uint256)
                      {
                          return _balanceOf(account);
                      }
                      /**
                       * @notice Sets a fiat token allowance for a spender to spend on behalf of the caller.
                       * @param spender The spender's address.
                       * @param value   The allowance amount.
                       * @return True if the operation was successful.
                       */
                      function approve(address spender, uint256 value)
                          external
                          virtual
                          override
                          whenNotPaused
                          notBlacklisted(msg.sender)
                          notBlacklisted(spender)
                          returns (bool)
                      {
                          _approve(msg.sender, spender, value);
                          return true;
                      }
                      /**
                       * @dev Internal function to set allowance.
                       * @param owner     Token owner's address.
                       * @param spender   Spender's address.
                       * @param value     Allowance amount.
                       */
                      function _approve(
                          address owner,
                          address spender,
                          uint256 value
                      ) internal override {
                          require(owner != address(0), "ERC20: approve from the zero address");
                          require(spender != address(0), "ERC20: approve to the zero address");
                          allowed[owner][spender] = value;
                          emit Approval(owner, spender, value);
                      }
                      /**
                       * @notice Transfers tokens from an address to another by spending the caller's allowance.
                       * @dev The caller must have some fiat token allowance on the payer's tokens.
                       * @param from  Payer's address.
                       * @param to    Payee's address.
                       * @param value Transfer amount.
                       * @return True if the operation was successful.
                       */
                      function transferFrom(
                          address from,
                          address to,
                          uint256 value
                      )
                          external
                          override
                          whenNotPaused
                          notBlacklisted(msg.sender)
                          notBlacklisted(from)
                          notBlacklisted(to)
                          returns (bool)
                      {
                          require(
                              value <= allowed[from][msg.sender],
                              "ERC20: transfer amount exceeds allowance"
                          );
                          _transfer(from, to, value);
                          allowed[from][msg.sender] = allowed[from][msg.sender].sub(value);
                          return true;
                      }
                      /**
                       * @notice Transfers tokens from the caller.
                       * @param to    Payee's address.
                       * @param value Transfer amount.
                       * @return True if the operation was successful.
                       */
                      function transfer(address to, uint256 value)
                          external
                          override
                          whenNotPaused
                          notBlacklisted(msg.sender)
                          notBlacklisted(to)
                          returns (bool)
                      {
                          _transfer(msg.sender, to, value);
                          return true;
                      }
                      /**
                       * @dev Internal function to process transfers.
                       * @param from  Payer's address.
                       * @param to    Payee's address.
                       * @param value Transfer amount.
                       */
                      function _transfer(
                          address from,
                          address to,
                          uint256 value
                      ) internal override {
                          require(from != address(0), "ERC20: transfer from the zero address");
                          require(to != address(0), "ERC20: transfer to the zero address");
                          require(
                              value <= _balanceOf(from),
                              "ERC20: transfer amount exceeds balance"
                          );
                          _setBalance(from, _balanceOf(from).sub(value));
                          _setBalance(to, _balanceOf(to).add(value));
                          emit Transfer(from, to, value);
                      }
                      /**
                       * @notice Adds or updates a new minter with a mint allowance.
                       * @param minter The address of the minter.
                       * @param minterAllowedAmount The minting amount allowed for the minter.
                       * @return True if the operation was successful.
                       */
                      function configureMinter(address minter, uint256 minterAllowedAmount)
                          external
                          whenNotPaused
                          onlyMasterMinter
                          returns (bool)
                      {
                          minters[minter] = true;
                          minterAllowed[minter] = minterAllowedAmount;
                          emit MinterConfigured(minter, minterAllowedAmount);
                          return true;
                      }
                      /**
                       * @notice Removes a minter.
                       * @param minter The address of the minter to remove.
                       * @return True if the operation was successful.
                       */
                      function removeMinter(address minter)
                          external
                          onlyMasterMinter
                          returns (bool)
                      {
                          minters[minter] = false;
                          minterAllowed[minter] = 0;
                          emit MinterRemoved(minter);
                          return true;
                      }
                      /**
                       * @notice Allows a minter to burn some of its own tokens.
                       * @dev The caller must be a minter, must not be blacklisted, and the amount to burn
                       * should be less than or equal to the account's balance.
                       * @param _amount the amount of tokens to be burned.
                       */
                      function burn(uint256 _amount)
                          external
                          whenNotPaused
                          onlyMinters
                          notBlacklisted(msg.sender)
                      {
                          uint256 balance = _balanceOf(msg.sender);
                          require(_amount > 0, "FiatToken: burn amount not greater than 0");
                          require(balance >= _amount, "FiatToken: burn amount exceeds balance");
                          totalSupply_ = totalSupply_.sub(_amount);
                          _setBalance(msg.sender, balance.sub(_amount));
                          emit Burn(msg.sender, _amount);
                          emit Transfer(msg.sender, address(0), _amount);
                      }
                      /**
                       * @notice Updates the master minter address.
                       * @param _newMasterMinter The address of the new master minter.
                       */
                      function updateMasterMinter(address _newMasterMinter) external onlyOwner {
                          require(
                              _newMasterMinter != address(0),
                              "FiatToken: new masterMinter is the zero address"
                          );
                          masterMinter = _newMasterMinter;
                          emit MasterMinterChanged(masterMinter);
                      }
                      /**
                       * @inheritdoc Blacklistable
                       */
                      function _blacklist(address _account) internal override {
                          _setBlacklistState(_account, true);
                      }
                      /**
                       * @inheritdoc Blacklistable
                       */
                      function _unBlacklist(address _account) internal override {
                          _setBlacklistState(_account, false);
                      }
                      /**
                       * @dev Helper method that sets the blacklist state of an account.
                       * @param _account         The address of the account.
                       * @param _shouldBlacklist True if the account should be blacklisted, false if the account should be unblacklisted.
                       */
                      function _setBlacklistState(address _account, bool _shouldBlacklist)
                          internal
                          virtual
                      {
                          _deprecatedBlacklisted[_account] = _shouldBlacklist;
                      }
                      /**
                       * @dev Helper method that sets the balance of an account.
                       * @param _account The address of the account.
                       * @param _balance The new fiat token balance of the account.
                       */
                      function _setBalance(address _account, uint256 _balance) internal virtual {
                          balanceAndBlacklistStates[_account] = _balance;
                      }
                      /**
                       * @inheritdoc Blacklistable
                       */
                      function _isBlacklisted(address _account)
                          internal
                          virtual
                          override
                          view
                          returns (bool)
                      {
                          return _deprecatedBlacklisted[_account];
                      }
                      /**
                       * @dev Helper method to obtain the balance of an account.
                       * @param _account  The address of the account.
                       * @return          The fiat token balance of the account.
                       */
                      function _balanceOf(address _account)
                          internal
                          virtual
                          view
                          returns (uint256)
                      {
                          return balanceAndBlacklistStates[_account];
                      }
                  }
                  /**
                   * SPDX-License-Identifier: Apache-2.0
                   *
                   * Copyright (c) 2023, Circle Internet Financial, LLC.
                   *
                   * Licensed under the Apache License, Version 2.0 (the "License");
                   * you may not use this file except in compliance with the License.
                   * You may obtain a copy of the License at
                   *
                   * http://www.apache.org/licenses/LICENSE-2.0
                   *
                   * Unless required by applicable law or agreed to in writing, software
                   * distributed under the License is distributed on an "AS IS" BASIS,
                   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                   * See the License for the specific language governing permissions and
                   * limitations under the License.
                   */
                  pragma solidity 0.6.12;
                  import { Ownable } from "./Ownable.sol";
                  /**
                   * @title Blacklistable Token
                   * @dev Allows accounts to be blacklisted by a "blacklister" role
                   */
                  abstract contract Blacklistable is Ownable {
                      address public blacklister;
                      mapping(address => bool) internal _deprecatedBlacklisted;
                      event Blacklisted(address indexed _account);
                      event UnBlacklisted(address indexed _account);
                      event BlacklisterChanged(address indexed newBlacklister);
                      /**
                       * @dev Throws if called by any account other than the blacklister.
                       */
                      modifier onlyBlacklister() {
                          require(
                              msg.sender == blacklister,
                              "Blacklistable: caller is not the blacklister"
                          );
                          _;
                      }
                      /**
                       * @dev Throws if argument account is blacklisted.
                       * @param _account The address to check.
                       */
                      modifier notBlacklisted(address _account) {
                          require(
                              !_isBlacklisted(_account),
                              "Blacklistable: account is blacklisted"
                          );
                          _;
                      }
                      /**
                       * @notice Checks if account is blacklisted.
                       * @param _account The address to check.
                       * @return True if the account is blacklisted, false if the account is not blacklisted.
                       */
                      function isBlacklisted(address _account) external view returns (bool) {
                          return _isBlacklisted(_account);
                      }
                      /**
                       * @notice Adds account to blacklist.
                       * @param _account The address to blacklist.
                       */
                      function blacklist(address _account) external onlyBlacklister {
                          _blacklist(_account);
                          emit Blacklisted(_account);
                      }
                      /**
                       * @notice Removes account from blacklist.
                       * @param _account The address to remove from the blacklist.
                       */
                      function unBlacklist(address _account) external onlyBlacklister {
                          _unBlacklist(_account);
                          emit UnBlacklisted(_account);
                      }
                      /**
                       * @notice Updates the blacklister address.
                       * @param _newBlacklister The address of the new blacklister.
                       */
                      function updateBlacklister(address _newBlacklister) external onlyOwner {
                          require(
                              _newBlacklister != address(0),
                              "Blacklistable: new blacklister is the zero address"
                          );
                          blacklister = _newBlacklister;
                          emit BlacklisterChanged(blacklister);
                      }
                      /**
                       * @dev Checks if account is blacklisted.
                       * @param _account The address to check.
                       * @return true if the account is blacklisted, false otherwise.
                       */
                      function _isBlacklisted(address _account)
                          internal
                          virtual
                          view
                          returns (bool);
                      /**
                       * @dev Helper method that blacklists an account.
                       * @param _account The address to blacklist.
                       */
                      function _blacklist(address _account) internal virtual;
                      /**
                       * @dev Helper method that unblacklists an account.
                       * @param _account The address to unblacklist.
                       */
                      function _unBlacklist(address _account) internal virtual;
                  }
                  /**
                   * SPDX-License-Identifier: Apache-2.0
                   *
                   * Copyright (c) 2023, Circle Internet Financial, LLC.
                   *
                   * Licensed under the Apache License, Version 2.0 (the "License");
                   * you may not use this file except in compliance with the License.
                   * You may obtain a copy of the License at
                   *
                   * http://www.apache.org/licenses/LICENSE-2.0
                   *
                   * Unless required by applicable law or agreed to in writing, software
                   * distributed under the License is distributed on an "AS IS" BASIS,
                   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                   * See the License for the specific language governing permissions and
                   * limitations under the License.
                   */
                  pragma solidity 0.6.12;
                  import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
                  abstract contract AbstractFiatTokenV1 is IERC20 {
                      function _approve(
                          address owner,
                          address spender,
                          uint256 value
                      ) internal virtual;
                      function _transfer(
                          address from,
                          address to,
                          uint256 value
                      ) internal virtual;
                  }
                  /**
                   * SPDX-License-Identifier: Apache-2.0
                   *
                   * Copyright (c) 2023, Circle Internet Financial, LLC.
                   *
                   * Licensed under the Apache License, Version 2.0 (the "License");
                   * you may not use this file except in compliance with the License.
                   * You may obtain a copy of the License at
                   *
                   * http://www.apache.org/licenses/LICENSE-2.0
                   *
                   * Unless required by applicable law or agreed to in writing, software
                   * distributed under the License is distributed on an "AS IS" BASIS,
                   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                   * See the License for the specific language governing permissions and
                   * limitations under the License.
                   */
                  pragma solidity 0.6.12;
                  import { Ownable } from "../v1/Ownable.sol";
                  import { IERC20 } from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
                  import { SafeERC20 } from "@openzeppelin/contracts/token/ERC20/SafeERC20.sol";
                  contract Rescuable is Ownable {
                      using SafeERC20 for IERC20;
                      address private _rescuer;
                      event RescuerChanged(address indexed newRescuer);
                      /**
                       * @notice Returns current rescuer
                       * @return Rescuer's address
                       */
                      function rescuer() external view returns (address) {
                          return _rescuer;
                      }
                      /**
                       * @notice Revert if called by any account other than the rescuer.
                       */
                      modifier onlyRescuer() {
                          require(msg.sender == _rescuer, "Rescuable: caller is not the rescuer");
                          _;
                      }
                      /**
                       * @notice Rescue ERC20 tokens locked up in this contract.
                       * @param tokenContract ERC20 token contract address
                       * @param to        Recipient address
                       * @param amount    Amount to withdraw
                       */
                      function rescueERC20(
                          IERC20 tokenContract,
                          address to,
                          uint256 amount
                      ) external onlyRescuer {
                          tokenContract.safeTransfer(to, amount);
                      }
                      /**
                       * @notice Updates the rescuer address.
                       * @param newRescuer The address of the new rescuer.
                       */
                      function updateRescuer(address newRescuer) external onlyOwner {
                          require(
                              newRescuer != address(0),
                              "Rescuable: new rescuer is the zero address"
                          );
                          _rescuer = newRescuer;
                          emit RescuerChanged(newRescuer);
                      }
                  }
                  /**
                   * SPDX-License-Identifier: Apache-2.0
                   *
                   * Copyright (c) 2023, Circle Internet Financial, LLC.
                   *
                   * Licensed under the Apache License, Version 2.0 (the "License");
                   * you may not use this file except in compliance with the License.
                   * You may obtain a copy of the License at
                   *
                   * http://www.apache.org/licenses/LICENSE-2.0
                   *
                   * Unless required by applicable law or agreed to in writing, software
                   * distributed under the License is distributed on an "AS IS" BASIS,
                   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                   * See the License for the specific language governing permissions and
                   * limitations under the License.
                   */
                  pragma solidity 0.6.12;
                  import { FiatTokenV1 } from "../v1/FiatTokenV1.sol";
                  import { Rescuable } from "./Rescuable.sol";
                  /**
                   * @title FiatTokenV1_1
                   * @dev ERC20 Token backed by fiat reserves
                   */
                  contract FiatTokenV1_1 is FiatTokenV1, Rescuable {
                  }
                  /**
                   * SPDX-License-Identifier: Apache-2.0
                   *
                   * Copyright (c) 2023, Circle Internet Financial, LLC.
                   *
                   * Licensed under the Apache License, Version 2.0 (the "License");
                   * you may not use this file except in compliance with the License.
                   * You may obtain a copy of the License at
                   *
                   * http://www.apache.org/licenses/LICENSE-2.0
                   *
                   * Unless required by applicable law or agreed to in writing, software
                   * distributed under the License is distributed on an "AS IS" BASIS,
                   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                   * See the License for the specific language governing permissions and
                   * limitations under the License.
                   */
                  pragma solidity 0.6.12;
                  import { ECRecover } from "./ECRecover.sol";
                  import { IERC1271 } from "../interface/IERC1271.sol";
                  /**
                   * @dev Signature verification helper that can be used instead of `ECRecover.recover` to seamlessly support both ECDSA
                   * signatures from externally owned accounts (EOAs) as well as ERC1271 signatures from smart contract wallets.
                   *
                   * Adapted from https://github.com/OpenZeppelin/openzeppelin-contracts/blob/21bb89ef5bfc789b9333eb05e3ba2b7b284ac77c/contracts/utils/cryptography/SignatureChecker.sol
                   */
                  library SignatureChecker {
                      /**
                       * @dev Checks if a signature is valid for a given signer and data hash. If the signer is a smart contract, the
                       * signature is validated against that smart contract using ERC1271, otherwise it's validated using `ECRecover.recover`.
                       * @param signer        Address of the claimed signer
                       * @param digest        Keccak-256 hash digest of the signed message
                       * @param signature     Signature byte array associated with hash
                       */
                      function isValidSignatureNow(
                          address signer,
                          bytes32 digest,
                          bytes memory signature
                      ) external view returns (bool) {
                          if (!isContract(signer)) {
                              return ECRecover.recover(digest, signature) == signer;
                          }
                          return isValidERC1271SignatureNow(signer, digest, signature);
                      }
                      /**
                       * @dev Checks if a signature is valid for a given signer and data hash. The signature is validated
                       * against the signer smart contract using ERC1271.
                       * @param signer        Address of the claimed signer
                       * @param digest        Keccak-256 hash digest of the signed message
                       * @param signature     Signature byte array associated with hash
                       *
                       * NOTE: Unlike ECDSA signatures, contract signatures are revocable, and the outcome of this function can thus
                       * change through time. It could return true at block N and false at block N+1 (or the opposite).
                       */
                      function isValidERC1271SignatureNow(
                          address signer,
                          bytes32 digest,
                          bytes memory signature
                      ) internal view returns (bool) {
                          (bool success, bytes memory result) = signer.staticcall(
                              abi.encodeWithSelector(
                                  IERC1271.isValidSignature.selector,
                                  digest,
                                  signature
                              )
                          );
                          return (success &&
                              result.length >= 32 &&
                              abi.decode(result, (bytes32)) ==
                              bytes32(IERC1271.isValidSignature.selector));
                      }
                      /**
                       * @dev Checks if the input address is a smart contract.
                       */
                      function isContract(address addr) internal view returns (bool) {
                          uint256 size;
                          assembly {
                              size := extcodesize(addr)
                          }
                          return size > 0;
                      }
                  }
                  /**
                   * SPDX-License-Identifier: Apache-2.0
                   *
                   * Copyright (c) 2023, Circle Internet Financial, LLC.
                   *
                   * Licensed under the Apache License, Version 2.0 (the "License");
                   * you may not use this file except in compliance with the License.
                   * You may obtain a copy of the License at
                   *
                   * http://www.apache.org/licenses/LICENSE-2.0
                   *
                   * Unless required by applicable law or agreed to in writing, software
                   * distributed under the License is distributed on an "AS IS" BASIS,
                   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                   * See the License for the specific language governing permissions and
                   * limitations under the License.
                   */
                  pragma solidity 0.6.12;
                  /**
                   * @dev Signature message hash utilities for producing digests to be consumed by {ECDSA} recovery or signing.
                   *
                   * The library provides methods for generating a hash of a message that conforms to the
                   * https://eips.ethereum.org/EIPS/eip-191[EIP 191] and https://eips.ethereum.org/EIPS/eip-712[EIP 712]
                   * specifications.
                   */
                  library MessageHashUtils {
                      /**
                       * @dev Returns the keccak256 digest of an EIP-712 typed data (EIP-191 version `0x01`).
                       * Adapted from https://github.com/OpenZeppelin/openzeppelin-contracts/blob/21bb89ef5bfc789b9333eb05e3ba2b7b284ac77c/contracts/utils/cryptography/MessageHashUtils.sol
                       *
                       * The digest is calculated from a `domainSeparator` and a `structHash`, by prefixing them with
                       * `\\x19\\x01` and hashing the result. It corresponds to the hash signed by the
                       * https://eips.ethereum.org/EIPS/eip-712[`eth_signTypedData`] JSON-RPC method as part of EIP-712.
                       *
                       * @param domainSeparator    Domain separator
                       * @param structHash         Hashed EIP-712 data struct
                       * @return digest            The keccak256 digest of an EIP-712 typed data
                       */
                      function toTypedDataHash(bytes32 domainSeparator, bytes32 structHash)
                          internal
                          pure
                          returns (bytes32 digest)
                      {
                          assembly {
                              let ptr := mload(0x40)
                              mstore(ptr, "\\x19\\x01")
                              mstore(add(ptr, 0x02), domainSeparator)
                              mstore(add(ptr, 0x22), structHash)
                              digest := keccak256(ptr, 0x42)
                          }
                      }
                  }
                  /**
                   * SPDX-License-Identifier: Apache-2.0
                   *
                   * Copyright (c) 2023, Circle Internet Financial, LLC.
                   *
                   * Licensed under the Apache License, Version 2.0 (the "License");
                   * you may not use this file except in compliance with the License.
                   * You may obtain a copy of the License at
                   *
                   * http://www.apache.org/licenses/LICENSE-2.0
                   *
                   * Unless required by applicable law or agreed to in writing, software
                   * distributed under the License is distributed on an "AS IS" BASIS,
                   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                   * See the License for the specific language governing permissions and
                   * limitations under the License.
                   */
                  pragma solidity 0.6.12;
                  /**
                   * @title EIP712
                   * @notice A library that provides EIP712 helper functions
                   */
                  library EIP712 {
                      /**
                       * @notice Make EIP712 domain separator
                       * @param name      Contract name
                       * @param version   Contract version
                       * @param chainId   Blockchain ID
                       * @return Domain separator
                       */
                      function makeDomainSeparator(
                          string memory name,
                          string memory version,
                          uint256 chainId
                      ) internal view returns (bytes32) {
                          return
                              keccak256(
                                  abi.encode(
                                      // keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)")
                                      0x8b73c3c69bb8fe3d512ecc4cf759cc79239f7b179b0ffacaa9a75d522b39400f,
                                      keccak256(bytes(name)),
                                      keccak256(bytes(version)),
                                      chainId,
                                      address(this)
                                  )
                              );
                      }
                      /**
                       * @notice Make EIP712 domain separator
                       * @param name      Contract name
                       * @param version   Contract version
                       * @return Domain separator
                       */
                      function makeDomainSeparator(string memory name, string memory version)
                          internal
                          view
                          returns (bytes32)
                      {
                          uint256 chainId;
                          assembly {
                              chainId := chainid()
                          }
                          return makeDomainSeparator(name, version, chainId);
                      }
                  }
                  /**
                   * SPDX-License-Identifier: Apache-2.0
                   *
                   * Copyright (c) 2023, Circle Internet Financial, LLC.
                   *
                   * Licensed under the Apache License, Version 2.0 (the "License");
                   * you may not use this file except in compliance with the License.
                   * You may obtain a copy of the License at
                   *
                   * http://www.apache.org/licenses/LICENSE-2.0
                   *
                   * Unless required by applicable law or agreed to in writing, software
                   * distributed under the License is distributed on an "AS IS" BASIS,
                   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                   * See the License for the specific language governing permissions and
                   * limitations under the License.
                   */
                  pragma solidity 0.6.12;
                  /**
                   * @title ECRecover
                   * @notice A library that provides a safe ECDSA recovery function
                   */
                  library ECRecover {
                      /**
                       * @notice Recover signer's address from a signed message
                       * @dev Adapted from: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/65e4ffde586ec89af3b7e9140bdc9235d1254853/contracts/cryptography/ECDSA.sol
                       * Modifications: Accept v, r, and s as separate arguments
                       * @param digest    Keccak-256 hash digest of the signed message
                       * @param v         v of the signature
                       * @param r         r of the signature
                       * @param s         s of the signature
                       * @return Signer address
                       */
                      function recover(
                          bytes32 digest,
                          uint8 v,
                          bytes32 r,
                          bytes32 s
                      ) internal pure returns (address) {
                          // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
                          // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
                          // the valid range for s in (281): 0 < s < secp256k1n ÷ 2 + 1, and for v in (282): v ∈ {27, 28}. Most
                          // signatures from current libraries generate a unique signature with an s-value in the lower half order.
                          //
                          // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
                          // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
                          // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
                          // these malleable signatures as well.
                          if (
                              uint256(s) >
                              0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0
                          ) {
                              revert("ECRecover: invalid signature 's' value");
                          }
                          if (v != 27 && v != 28) {
                              revert("ECRecover: invalid signature 'v' value");
                          }
                          // If the signature is valid (and not malleable), return the signer address
                          address signer = ecrecover(digest, v, r, s);
                          require(signer != address(0), "ECRecover: invalid signature");
                          return signer;
                      }
                      /**
                       * @notice Recover signer's address from a signed message
                       * @dev Adapted from: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/0053ee040a7ff1dbc39691c9e67a69f564930a88/contracts/utils/cryptography/ECDSA.sol
                       * @param digest    Keccak-256 hash digest of the signed message
                       * @param signature Signature byte array associated with hash
                       * @return Signer address
                       */
                      function recover(bytes32 digest, bytes memory signature)
                          internal
                          pure
                          returns (address)
                      {
                          require(signature.length == 65, "ECRecover: invalid signature length");
                          bytes32 r;
                          bytes32 s;
                          uint8 v;
                          // ecrecover takes the signature parameters, and the only way to get them
                          // currently is to use assembly.
                          /// @solidity memory-safe-assembly
                          assembly {
                              r := mload(add(signature, 0x20))
                              s := mload(add(signature, 0x40))
                              v := byte(0, mload(add(signature, 0x60)))
                          }
                          return recover(digest, v, r, s);
                      }
                  }
                  /**
                   * SPDX-License-Identifier: Apache-2.0
                   *
                   * Copyright (c) 2023, Circle Internet Financial, LLC.
                   *
                   * Licensed under the Apache License, Version 2.0 (the "License");
                   * you may not use this file except in compliance with the License.
                   * You may obtain a copy of the License at
                   *
                   * http://www.apache.org/licenses/LICENSE-2.0
                   *
                   * Unless required by applicable law or agreed to in writing, software
                   * distributed under the License is distributed on an "AS IS" BASIS,
                   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
                   * See the License for the specific language governing permissions and
                   * limitations under the License.
                   */
                  pragma solidity 0.6.12;
                  /**
                   * @dev Interface of the ERC1271 standard signature validation method for
                   * contracts as defined in https://eips.ethereum.org/EIPS/eip-1271[ERC-1271].
                   */
                  interface IERC1271 {
                      /**
                       * @dev Should return whether the signature provided is valid for the provided data
                       * @param hash          Hash of the data to be signed
                       * @param signature     Signature byte array associated with the provided data hash
                       * @return magicValue   bytes4 magic value 0x1626ba7e when function passes
                       */
                      function isValidSignature(bytes32 hash, bytes memory signature)
                          external
                          view
                          returns (bytes4 magicValue);
                  }