ETH Price: $3,486.62 (+1.84%)

Transaction Decoder

Block:
23038442 at Jul-31-2025 10:17:59 AM +UTC
Transaction Fee:
0.00064556729866761 ETH $2.25
Gas Used:
184,305 Gas / 3.502711802 Gwei

Account State Difference:

  Address   Before After State Difference Code
0x23E5b62B...8e8a5e622
0.001585167551340291 Eth
Nonce: 4
0.000939600252672681 Eth
Nonce: 5
0.00064556729866761
(Titan Builder)
46.690320089416859769 Eth46.690441072206890289 Eth0.00012098279003052

Execution Trace

CErc20.mint( mintAmount=90000000 )
  • FiatTokenProxy.70a08231( )
    • FiatTokenV2_2.balanceOf( account=0x39AA39c021dfbaE8faC545936693aC917d5E7563 ) => ( 17170078070063 )
    • LegacyJumpRateModelV2.getBorrowRate( cash=17170078070063, borrows=32535846020779, reserves=9897494073988 ) => ( 0, 28000568469 )
    • Unitroller.4ef4c3e1( )
      • Comptroller.mintAllowed( cToken=0x39AA39c021dfbaE8faC545936693aC917d5E7563, minter=0x23E5b62B39eBeD7b36B2D24D96EA7768e8a5e622, mintAmount=90000000 ) => ( 0 )
        • CErc20.balanceOf( owner=0x23E5b62B39eBeD7b36B2D24D96EA7768e8a5e622 ) => ( 0 )
        • FiatTokenProxy.dd62ed3e( )
          • FiatTokenV2_2.allowance( owner=0x23E5b62B39eBeD7b36B2D24D96EA7768e8a5e622, spender=0x39AA39c021dfbaE8faC545936693aC917d5E7563 ) => ( 115792089237316195423570985008687907853269984665640564039457584007913129639935 )
          • FiatTokenProxy.70a08231( )
            • FiatTokenV2_2.balanceOf( account=0x23E5b62B39eBeD7b36B2D24D96EA7768e8a5e622 ) => ( 90334484 )
            • FiatTokenProxy.70a08231( )
              • FiatTokenV2_2.balanceOf( account=0x39AA39c021dfbaE8faC545936693aC917d5E7563 ) => ( 17170078070063 )
              • FiatTokenProxy.23b872dd( )
                • FiatTokenV2_2.transferFrom( from=0x23E5b62B39eBeD7b36B2D24D96EA7768e8a5e622, to=0x39AA39c021dfbaE8faC545936693aC917d5E7563, value=90000000 ) => ( True )
                  File 1 of 6: CErc20
                  // File: contracts/ComptrollerInterface.sol
                  
                  pragma solidity ^0.5.8;
                  
                  interface ComptrollerInterface {
                      /**
                       * @notice Marker function used for light validation when updating the comptroller of a market
                       * @dev Implementations should simply return true.
                       * @return true
                       */
                      function isComptroller() external view returns (bool);
                  
                      /*** Assets You Are In ***/
                  
                      function enterMarkets(address[] calldata cTokens) external returns (uint[] memory);
                      function exitMarket(address cToken) external returns (uint);
                  
                      /*** Policy Hooks ***/
                  
                      function mintAllowed(address cToken, address minter, uint mintAmount) external returns (uint);
                      function mintVerify(address cToken, address minter, uint mintAmount, uint mintTokens) external;
                  
                      function redeemAllowed(address cToken, address redeemer, uint redeemTokens) external returns (uint);
                      function redeemVerify(address cToken, address redeemer, uint redeemAmount, uint redeemTokens) external;
                  
                      function borrowAllowed(address cToken, address borrower, uint borrowAmount) external returns (uint);
                      function borrowVerify(address cToken, address borrower, uint borrowAmount) external;
                  
                      function repayBorrowAllowed(
                          address cToken,
                          address payer,
                          address borrower,
                          uint repayAmount) external returns (uint);
                      function repayBorrowVerify(
                          address cToken,
                          address payer,
                          address borrower,
                          uint repayAmount,
                          uint borrowerIndex) external;
                  
                      function liquidateBorrowAllowed(
                          address cTokenBorrowed,
                          address cTokenCollateral,
                          address liquidator,
                          address borrower,
                          uint repayAmount) external returns (uint);
                      function liquidateBorrowVerify(
                          address cTokenBorrowed,
                          address cTokenCollateral,
                          address liquidator,
                          address borrower,
                          uint repayAmount,
                          uint seizeTokens) external;
                  
                      function seizeAllowed(
                          address cTokenCollateral,
                          address cTokenBorrowed,
                          address liquidator,
                          address borrower,
                          uint seizeTokens) external returns (uint);
                      function seizeVerify(
                          address cTokenCollateral,
                          address cTokenBorrowed,
                          address liquidator,
                          address borrower,
                          uint seizeTokens) external;
                  
                      function transferAllowed(address cToken, address src, address dst, uint transferTokens) external returns (uint);
                      function transferVerify(address cToken, address src, address dst, uint transferTokens) external;
                  
                      /*** Liquidity/Liquidation Calculations ***/
                  
                      function liquidateCalculateSeizeTokens(
                          address cTokenBorrowed,
                          address cTokenCollateral,
                          uint repayAmount) external view returns (uint, uint);
                  }
                  
                  // File: contracts/ErrorReporter.sol
                  
                  pragma solidity ^0.5.8;
                  
                  contract ComptrollerErrorReporter {
                      enum Error {
                          NO_ERROR,
                          UNAUTHORIZED,
                          COMPTROLLER_MISMATCH,
                          INSUFFICIENT_SHORTFALL,
                          INSUFFICIENT_LIQUIDITY,
                          INVALID_CLOSE_FACTOR,
                          INVALID_COLLATERAL_FACTOR,
                          INVALID_LIQUIDATION_INCENTIVE,
                          MARKET_NOT_ENTERED,
                          MARKET_NOT_LISTED,
                          MARKET_ALREADY_LISTED,
                          MATH_ERROR,
                          NONZERO_BORROW_BALANCE,
                          PRICE_ERROR,
                          REJECTION,
                          SNAPSHOT_ERROR,
                          TOO_MANY_ASSETS,
                          TOO_MUCH_REPAY
                      }
                  
                      enum FailureInfo {
                          ACCEPT_ADMIN_PENDING_ADMIN_CHECK,
                          ACCEPT_PENDING_IMPLEMENTATION_ADDRESS_CHECK,
                          EXIT_MARKET_BALANCE_OWED,
                          EXIT_MARKET_REJECTION,
                          SET_CLOSE_FACTOR_OWNER_CHECK,
                          SET_CLOSE_FACTOR_VALIDATION,
                          SET_COLLATERAL_FACTOR_OWNER_CHECK,
                          SET_COLLATERAL_FACTOR_NO_EXISTS,
                          SET_COLLATERAL_FACTOR_VALIDATION,
                          SET_COLLATERAL_FACTOR_WITHOUT_PRICE,
                          SET_IMPLEMENTATION_OWNER_CHECK,
                          SET_LIQUIDATION_INCENTIVE_OWNER_CHECK,
                          SET_LIQUIDATION_INCENTIVE_VALIDATION,
                          SET_MAX_ASSETS_OWNER_CHECK,
                          SET_PENDING_ADMIN_OWNER_CHECK,
                          SET_PENDING_IMPLEMENTATION_OWNER_CHECK,
                          SET_PRICE_ORACLE_OWNER_CHECK,
                          SUPPORT_MARKET_EXISTS,
                          SUPPORT_MARKET_OWNER_CHECK,
                          ZUNUSED
                      }
                  
                      /**
                        * @dev `error` corresponds to enum Error; `info` corresponds to enum FailureInfo, and `detail` is an arbitrary
                        * contract-specific code that enables us to report opaque error codes from upgradeable contracts.
                        **/
                      event Failure(uint error, uint info, uint detail);
                  
                      /**
                        * @dev use this when reporting a known error from the money market or a non-upgradeable collaborator
                        */
                      function fail(Error err, FailureInfo info) internal returns (uint) {
                          emit Failure(uint(err), uint(info), 0);
                  
                          return uint(err);
                      }
                  
                      /**
                        * @dev use this when reporting an opaque error from an upgradeable collaborator contract
                        */
                      function failOpaque(Error err, FailureInfo info, uint opaqueError) internal returns (uint) {
                          emit Failure(uint(err), uint(info), opaqueError);
                  
                          return uint(err);
                      }
                  }
                  
                  contract TokenErrorReporter {
                      enum Error {
                          NO_ERROR,
                          UNAUTHORIZED,
                          BAD_INPUT,
                          COMPTROLLER_REJECTION,
                          COMPTROLLER_CALCULATION_ERROR,
                          INTEREST_RATE_MODEL_ERROR,
                          INVALID_ACCOUNT_PAIR,
                          INVALID_CLOSE_AMOUNT_REQUESTED,
                          INVALID_COLLATERAL_FACTOR,
                          MATH_ERROR,
                          MARKET_NOT_FRESH,
                          MARKET_NOT_LISTED,
                          TOKEN_INSUFFICIENT_ALLOWANCE,
                          TOKEN_INSUFFICIENT_BALANCE,
                          TOKEN_INSUFFICIENT_CASH,
                          TOKEN_TRANSFER_IN_FAILED,
                          TOKEN_TRANSFER_OUT_FAILED
                      }
                  
                      /*
                       * Note: FailureInfo (but not Error) is kept in alphabetical order
                       *       This is because FailureInfo grows significantly faster, and
                       *       the order of Error has some meaning, while the order of FailureInfo
                       *       is entirely arbitrary.
                       */
                      enum FailureInfo {
                          ACCEPT_ADMIN_PENDING_ADMIN_CHECK,
                          ACCRUE_INTEREST_ACCUMULATED_INTEREST_CALCULATION_FAILED,
                          ACCRUE_INTEREST_BORROW_RATE_CALCULATION_FAILED,
                          ACCRUE_INTEREST_NEW_BORROW_INDEX_CALCULATION_FAILED,
                          ACCRUE_INTEREST_NEW_TOTAL_BORROWS_CALCULATION_FAILED,
                          ACCRUE_INTEREST_NEW_TOTAL_RESERVES_CALCULATION_FAILED,
                          ACCRUE_INTEREST_SIMPLE_INTEREST_FACTOR_CALCULATION_FAILED,
                          BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED,
                          BORROW_ACCRUE_INTEREST_FAILED,
                          BORROW_CASH_NOT_AVAILABLE,
                          BORROW_FRESHNESS_CHECK,
                          BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED,
                          BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED,
                          BORROW_MARKET_NOT_LISTED,
                          BORROW_COMPTROLLER_REJECTION,
                          LIQUIDATE_ACCRUE_BORROW_INTEREST_FAILED,
                          LIQUIDATE_ACCRUE_COLLATERAL_INTEREST_FAILED,
                          LIQUIDATE_COLLATERAL_FRESHNESS_CHECK,
                          LIQUIDATE_COMPTROLLER_REJECTION,
                          LIQUIDATE_COMPTROLLER_CALCULATE_AMOUNT_SEIZE_FAILED,
                          LIQUIDATE_CLOSE_AMOUNT_IS_UINT_MAX,
                          LIQUIDATE_CLOSE_AMOUNT_IS_ZERO,
                          LIQUIDATE_FRESHNESS_CHECK,
                          LIQUIDATE_LIQUIDATOR_IS_BORROWER,
                          LIQUIDATE_REPAY_BORROW_FRESH_FAILED,
                          LIQUIDATE_SEIZE_BALANCE_INCREMENT_FAILED,
                          LIQUIDATE_SEIZE_BALANCE_DECREMENT_FAILED,
                          LIQUIDATE_SEIZE_COMPTROLLER_REJECTION,
                          LIQUIDATE_SEIZE_LIQUIDATOR_IS_BORROWER,
                          LIQUIDATE_SEIZE_TOO_MUCH,
                          MINT_ACCRUE_INTEREST_FAILED,
                          MINT_COMPTROLLER_REJECTION,
                          MINT_EXCHANGE_CALCULATION_FAILED,
                          MINT_EXCHANGE_RATE_READ_FAILED,
                          MINT_FRESHNESS_CHECK,
                          MINT_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED,
                          MINT_NEW_TOTAL_SUPPLY_CALCULATION_FAILED,
                          MINT_TRANSFER_IN_FAILED,
                          MINT_TRANSFER_IN_NOT_POSSIBLE,
                          REDEEM_ACCRUE_INTEREST_FAILED,
                          REDEEM_COMPTROLLER_REJECTION,
                          REDEEM_EXCHANGE_TOKENS_CALCULATION_FAILED,
                          REDEEM_EXCHANGE_AMOUNT_CALCULATION_FAILED,
                          REDEEM_EXCHANGE_RATE_READ_FAILED,
                          REDEEM_FRESHNESS_CHECK,
                          REDEEM_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED,
                          REDEEM_NEW_TOTAL_SUPPLY_CALCULATION_FAILED,
                          REDEEM_TRANSFER_OUT_NOT_POSSIBLE,
                          REDUCE_RESERVES_ACCRUE_INTEREST_FAILED,
                          REDUCE_RESERVES_ADMIN_CHECK,
                          REDUCE_RESERVES_CASH_NOT_AVAILABLE,
                          REDUCE_RESERVES_FRESH_CHECK,
                          REDUCE_RESERVES_VALIDATION,
                          REPAY_BEHALF_ACCRUE_INTEREST_FAILED,
                          REPAY_BORROW_ACCRUE_INTEREST_FAILED,
                          REPAY_BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED,
                          REPAY_BORROW_COMPTROLLER_REJECTION,
                          REPAY_BORROW_FRESHNESS_CHECK,
                          REPAY_BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED,
                          REPAY_BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED,
                          REPAY_BORROW_TRANSFER_IN_NOT_POSSIBLE,
                          SET_COLLATERAL_FACTOR_OWNER_CHECK,
                          SET_COLLATERAL_FACTOR_VALIDATION,
                          SET_COMPTROLLER_OWNER_CHECK,
                          SET_INTEREST_RATE_MODEL_ACCRUE_INTEREST_FAILED,
                          SET_INTEREST_RATE_MODEL_FRESH_CHECK,
                          SET_INTEREST_RATE_MODEL_OWNER_CHECK,
                          SET_MAX_ASSETS_OWNER_CHECK,
                          SET_ORACLE_MARKET_NOT_LISTED,
                          SET_PENDING_ADMIN_OWNER_CHECK,
                          SET_RESERVE_FACTOR_ACCRUE_INTEREST_FAILED,
                          SET_RESERVE_FACTOR_ADMIN_CHECK,
                          SET_RESERVE_FACTOR_FRESH_CHECK,
                          SET_RESERVE_FACTOR_BOUNDS_CHECK,
                          TRANSFER_COMPTROLLER_REJECTION,
                          TRANSFER_NOT_ALLOWED,
                          TRANSFER_NOT_ENOUGH,
                          TRANSFER_TOO_MUCH
                      }
                  
                      /**
                        * @dev `error` corresponds to enum Error; `info` corresponds to enum FailureInfo, and `detail` is an arbitrary
                        * contract-specific code that enables us to report opaque error codes from upgradeable contracts.
                        **/
                      event Failure(uint error, uint info, uint detail);
                  
                      /**
                        * @dev use this when reporting a known error from the money market or a non-upgradeable collaborator
                        */
                      function fail(Error err, FailureInfo info) internal returns (uint) {
                          emit Failure(uint(err), uint(info), 0);
                  
                          return uint(err);
                      }
                  
                      /**
                        * @dev use this when reporting an opaque error from an upgradeable collaborator contract
                        */
                      function failOpaque(Error err, FailureInfo info, uint opaqueError) internal returns (uint) {
                          emit Failure(uint(err), uint(info), opaqueError);
                  
                          return uint(err);
                      }
                  }
                  
                  // File: contracts/CarefulMath.sol
                  
                  pragma solidity ^0.5.8;
                  
                  /**
                    * @title Careful Math
                    * @author Compound
                    * @notice Derived from OpenZeppelin's SafeMath library
                    *         https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/math/SafeMath.sol
                    */
                  contract CarefulMath {
                  
                      /**
                       * @dev Possible error codes that we can return
                       */
                      enum MathError {
                          NO_ERROR,
                          DIVISION_BY_ZERO,
                          INTEGER_OVERFLOW,
                          INTEGER_UNDERFLOW
                      }
                  
                      /**
                      * @dev Multiplies two numbers, returns an error on overflow.
                      */
                      function mulUInt(uint a, uint b) internal pure returns (MathError, uint) {
                          if (a == 0) {
                              return (MathError.NO_ERROR, 0);
                          }
                  
                          uint c = a * b;
                  
                          if (c / a != b) {
                              return (MathError.INTEGER_OVERFLOW, 0);
                          } else {
                              return (MathError.NO_ERROR, c);
                          }
                      }
                  
                      /**
                      * @dev Integer division of two numbers, truncating the quotient.
                      */
                      function divUInt(uint a, uint b) internal pure returns (MathError, uint) {
                          if (b == 0) {
                              return (MathError.DIVISION_BY_ZERO, 0);
                          }
                  
                          return (MathError.NO_ERROR, a / b);
                      }
                  
                      /**
                      * @dev Subtracts two numbers, returns an error on overflow (i.e. if subtrahend is greater than minuend).
                      */
                      function subUInt(uint a, uint b) internal pure returns (MathError, uint) {
                          if (b <= a) {
                              return (MathError.NO_ERROR, a - b);
                          } else {
                              return (MathError.INTEGER_UNDERFLOW, 0);
                          }
                      }
                  
                      /**
                      * @dev Adds two numbers, returns an error on overflow.
                      */
                      function addUInt(uint a, uint b) internal pure returns (MathError, uint) {
                          uint c = a + b;
                  
                          if (c >= a) {
                              return (MathError.NO_ERROR, c);
                          } else {
                              return (MathError.INTEGER_OVERFLOW, 0);
                          }
                      }
                  
                      /**
                      * @dev add a and b and then subtract c
                      */
                      function addThenSubUInt(uint a, uint b, uint c) internal pure returns (MathError, uint) {
                          (MathError err0, uint sum) = addUInt(a, b);
                  
                          if (err0 != MathError.NO_ERROR) {
                              return (err0, 0);
                          }
                  
                          return subUInt(sum, c);
                      }
                  }
                  
                  // File: contracts/Exponential.sol
                  
                  pragma solidity ^0.5.8;
                  
                  
                  /**
                   * @title Exponential module for storing fixed-decision decimals
                   * @author Compound
                   * @notice Exp is a struct which stores decimals with a fixed precision of 18 decimal places.
                   *         Thus, if we wanted to store the 5.1, mantissa would store 5.1e18. That is:
                   *         `Exp({mantissa: 5100000000000000000})`.
                   */
                  contract Exponential is CarefulMath {
                      uint constant expScale = 1e18;
                      uint constant halfExpScale = expScale/2;
                      uint constant mantissaOne = expScale;
                  
                      struct Exp {
                          uint mantissa;
                      }
                  
                      /**
                       * @dev Creates an exponential from numerator and denominator values.
                       *      Note: Returns an error if (`num` * 10e18) > MAX_INT,
                       *            or if `denom` is zero.
                       */
                      function getExp(uint num, uint denom) pure internal returns (MathError, Exp memory) {
                          (MathError err0, uint scaledNumerator) = mulUInt(num, expScale);
                          if (err0 != MathError.NO_ERROR) {
                              return (err0, Exp({mantissa: 0}));
                          }
                  
                          (MathError err1, uint rational) = divUInt(scaledNumerator, denom);
                          if (err1 != MathError.NO_ERROR) {
                              return (err1, Exp({mantissa: 0}));
                          }
                  
                          return (MathError.NO_ERROR, Exp({mantissa: rational}));
                      }
                  
                      /**
                       * @dev Adds two exponentials, returning a new exponential.
                       */
                      function addExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
                          (MathError error, uint result) = addUInt(a.mantissa, b.mantissa);
                  
                          return (error, Exp({mantissa: result}));
                      }
                  
                      /**
                       * @dev Subtracts two exponentials, returning a new exponential.
                       */
                      function subExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
                          (MathError error, uint result) = subUInt(a.mantissa, b.mantissa);
                  
                          return (error, Exp({mantissa: result}));
                      }
                  
                      /**
                       * @dev Multiply an Exp by a scalar, returning a new Exp.
                       */
                      function mulScalar(Exp memory a, uint scalar) pure internal returns (MathError, Exp memory) {
                          (MathError err0, uint scaledMantissa) = mulUInt(a.mantissa, scalar);
                          if (err0 != MathError.NO_ERROR) {
                              return (err0, Exp({mantissa: 0}));
                          }
                  
                          return (MathError.NO_ERROR, Exp({mantissa: scaledMantissa}));
                      }
                  
                      /**
                       * @dev Multiply an Exp by a scalar, then truncate to return an unsigned integer.
                       */
                      function mulScalarTruncate(Exp memory a, uint scalar) pure internal returns (MathError, uint) {
                          (MathError err, Exp memory product) = mulScalar(a, scalar);
                          if (err != MathError.NO_ERROR) {
                              return (err, 0);
                          }
                  
                          return (MathError.NO_ERROR, truncate(product));
                      }
                  
                      /**
                       * @dev Multiply an Exp by a scalar, truncate, then add an to an unsigned integer, returning an unsigned integer.
                       */
                      function mulScalarTruncateAddUInt(Exp memory a, uint scalar, uint addend) pure internal returns (MathError, uint) {
                          (MathError err, Exp memory product) = mulScalar(a, scalar);
                          if (err != MathError.NO_ERROR) {
                              return (err, 0);
                          }
                  
                          return addUInt(truncate(product), addend);
                      }
                  
                      /**
                       * @dev Divide an Exp by a scalar, returning a new Exp.
                       */
                      function divScalar(Exp memory a, uint scalar) pure internal returns (MathError, Exp memory) {
                          (MathError err0, uint descaledMantissa) = divUInt(a.mantissa, scalar);
                          if (err0 != MathError.NO_ERROR) {
                              return (err0, Exp({mantissa: 0}));
                          }
                  
                          return (MathError.NO_ERROR, Exp({mantissa: descaledMantissa}));
                      }
                  
                      /**
                       * @dev Divide a scalar by an Exp, returning a new Exp.
                       */
                      function divScalarByExp(uint scalar, Exp memory divisor) pure internal returns (MathError, Exp memory) {
                          /*
                            We are doing this as:
                            getExp(mulUInt(expScale, scalar), divisor.mantissa)
                  
                            How it works:
                            Exp = a / b;
                            Scalar = s;
                            `s / (a / b)` = `b * s / a` and since for an Exp `a = mantissa, b = expScale`
                          */
                          (MathError err0, uint numerator) = mulUInt(expScale, scalar);
                          if (err0 != MathError.NO_ERROR) {
                              return (err0, Exp({mantissa: 0}));
                          }
                          return getExp(numerator, divisor.mantissa);
                      }
                  
                      /**
                       * @dev Divide a scalar by an Exp, then truncate to return an unsigned integer.
                       */
                      function divScalarByExpTruncate(uint scalar, Exp memory divisor) pure internal returns (MathError, uint) {
                          (MathError err, Exp memory fraction) = divScalarByExp(scalar, divisor);
                          if (err != MathError.NO_ERROR) {
                              return (err, 0);
                          }
                  
                          return (MathError.NO_ERROR, truncate(fraction));
                      }
                  
                      /**
                       * @dev Multiplies two exponentials, returning a new exponential.
                       */
                      function mulExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
                  
                          (MathError err0, uint doubleScaledProduct) = mulUInt(a.mantissa, b.mantissa);
                          if (err0 != MathError.NO_ERROR) {
                              return (err0, Exp({mantissa: 0}));
                          }
                  
                          // We add half the scale before dividing so that we get rounding instead of truncation.
                          //  See "Listing 6" and text above it at https://accu.org/index.php/journals/1717
                          // Without this change, a result like 6.6...e-19 will be truncated to 0 instead of being rounded to 1e-18.
                          (MathError err1, uint doubleScaledProductWithHalfScale) = addUInt(halfExpScale, doubleScaledProduct);
                          if (err1 != MathError.NO_ERROR) {
                              return (err1, Exp({mantissa: 0}));
                          }
                  
                          (MathError err2, uint product) = divUInt(doubleScaledProductWithHalfScale, expScale);
                          // The only error `div` can return is MathError.DIVISION_BY_ZERO but we control `expScale` and it is not zero.
                          assert(err2 == MathError.NO_ERROR);
                  
                          return (MathError.NO_ERROR, Exp({mantissa: product}));
                      }
                  
                      /**
                       * @dev Multiplies two exponentials given their mantissas, returning a new exponential.
                       */
                      function mulExp(uint a, uint b) pure internal returns (MathError, Exp memory) {
                          return mulExp(Exp({mantissa: a}), Exp({mantissa: b}));
                      }
                  
                      /**
                       * @dev Multiplies three exponentials, returning a new exponential.
                       */
                      function mulExp3(Exp memory a, Exp memory b, Exp memory c) pure internal returns (MathError, Exp memory) {
                          (MathError err, Exp memory ab) = mulExp(a, b);
                          if (err != MathError.NO_ERROR) {
                              return (err, ab);
                          }
                          return mulExp(ab, c);
                      }
                  
                      /**
                       * @dev Divides two exponentials, returning a new exponential.
                       *     (a/scale) / (b/scale) = (a/scale) * (scale/b) = a/b,
                       *  which we can scale as an Exp by calling getExp(a.mantissa, b.mantissa)
                       */
                      function divExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
                          return getExp(a.mantissa, b.mantissa);
                      }
                  
                      /**
                       * @dev Truncates the given exp to a whole number value.
                       *      For example, truncate(Exp{mantissa: 15 * expScale}) = 15
                       */
                      function truncate(Exp memory exp) pure internal returns (uint) {
                          // Note: We are not using careful math here as we're performing a division that cannot fail
                          return exp.mantissa / expScale;
                      }
                  
                      /**
                       * @dev Checks if first Exp is less than second Exp.
                       */
                      function lessThanExp(Exp memory left, Exp memory right) pure internal returns (bool) {
                          return left.mantissa < right.mantissa; //TODO: Add some simple tests and this in another PR yo.
                      }
                  
                      /**
                       * @dev Checks if left Exp <= right Exp.
                       */
                      function lessThanOrEqualExp(Exp memory left, Exp memory right) pure internal returns (bool) {
                          return left.mantissa <= right.mantissa;
                      }
                  
                      /**
                       * @dev returns true if Exp is exactly zero
                       */
                      function isZeroExp(Exp memory value) pure internal returns (bool) {
                          return value.mantissa == 0;
                      }
                  }
                  
                  // File: contracts/EIP20Interface.sol
                  
                  pragma solidity ^0.5.8;
                  
                  /**
                   * @title ERC 20 Token Standard Interface
                   *  https://eips.ethereum.org/EIPS/eip-20
                   */
                  interface EIP20Interface {
                  
                      /**
                        * @notice Get the total number of tokens in circulation
                        * @return The supply of tokens
                        */
                      function totalSupply() external view returns (uint256);
                  
                      /**
                       * @notice Gets the balance of the specified address
                       * @param owner The address from which the balance will be retrieved
                       * @return The balance
                       */
                      function balanceOf(address owner) external view returns (uint256 balance);
                  
                      /**
                        * @notice Transfer `amount` tokens from `msg.sender` to `dst`
                        * @param dst The address of the destination account
                        * @param amount The number of tokens to transfer
                        * @return Whether or not the transfer succeeded
                        */
                      function transfer(address dst, uint256 amount) external returns (bool success);
                  
                      /**
                        * @notice Transfer `amount` tokens from `src` to `dst`
                        * @param src The address of the source account
                        * @param dst The address of the destination account
                        * @param amount The number of tokens to transfer
                        * @return Whether or not the transfer succeeded
                        */
                      function transferFrom(address src, address dst, uint256 amount) external returns (bool success);
                  
                      /**
                        * @notice Approve `spender` to transfer up to `amount` from `src`
                        * @dev This will overwrite the approval amount for `spender`
                        *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
                        * @param spender The address of the account which may transfer tokens
                        * @param amount The number of tokens that are approved (-1 means infinite)
                        * @return Whether or not the approval succeeded
                        */
                      function approve(address spender, uint256 amount) external returns (bool success);
                  
                      /**
                        * @notice Get the current allowance from `owner` for `spender`
                        * @param owner The address of the account which owns the tokens to be spent
                        * @param spender The address of the account which may transfer tokens
                        * @return The number of tokens allowed to be spent (-1 means infinite)
                        */
                      function allowance(address owner, address spender) external view returns (uint256 remaining);
                  
                      event Transfer(address indexed from, address indexed to, uint256 amount);
                      event Approval(address indexed owner, address indexed spender, uint256 amount);
                  }
                  
                  // File: contracts/EIP20NonStandardInterface.sol
                  
                  pragma solidity ^0.5.8;
                  
                  /**
                   * @title EIP20NonStandardInterface
                   * @dev Version of ERC20 with no return values for `transfer` and `transferFrom`
                   *  See https://medium.com/coinmonks/missing-return-value-bug-at-least-130-tokens-affected-d67bf08521ca
                   */
                  interface EIP20NonStandardInterface {
                  
                      /**
                       * @notice Get the total number of tokens in circulation
                       * @return The supply of tokens
                       */
                      function totalSupply() external view returns (uint256);
                  
                      /**
                       * @notice Gets the balance of the specified address
                       * @param owner The address from which the balance will be retrieved
                       * @return The balance
                       */
                      function balanceOf(address owner) external view returns (uint256 balance);
                  
                      ///
                      /// !!!!!!!!!!!!!!
                      /// !!! NOTICE !!! `transfer` does not return a value, in violation of the ERC-20 specification
                      /// !!!!!!!!!!!!!!
                      ///
                  
                      /**
                        * @notice Transfer `amount` tokens from `msg.sender` to `dst`
                        * @param dst The address of the destination account
                        * @param amount The number of tokens to transfer
                        */
                      function transfer(address dst, uint256 amount) external;
                  
                      ///
                      /// !!!!!!!!!!!!!!
                      /// !!! NOTICE !!! `transferFrom` does not return a value, in violation of the ERC-20 specification
                      /// !!!!!!!!!!!!!!
                      ///
                  
                      /**
                        * @notice Transfer `amount` tokens from `src` to `dst`
                        * @param src The address of the source account
                        * @param dst The address of the destination account
                        * @param amount The number of tokens to transfer
                        */
                      function transferFrom(address src, address dst, uint256 amount) external;
                  
                      /**
                        * @notice Approve `spender` to transfer up to `amount` from `src`
                        * @dev This will overwrite the approval amount for `spender`
                        *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
                        * @param spender The address of the account which may transfer tokens
                        * @param amount The number of tokens that are approved
                        * @return Whether or not the approval succeeded
                        */
                      function approve(address spender, uint256 amount) external returns (bool success);
                  
                      /**
                        * @notice Get the current allowance from `owner` for `spender`
                        * @param owner The address of the account which owns the tokens to be spent
                        * @param spender The address of the account which may transfer tokens
                        * @return The number of tokens allowed to be spent
                        */
                      function allowance(address owner, address spender) external view returns (uint256 remaining);
                  
                      event Transfer(address indexed from, address indexed to, uint256 amount);
                      event Approval(address indexed owner, address indexed spender, uint256 amount);
                  }
                  
                  // File: contracts/ReentrancyGuard.sol
                  
                  pragma solidity ^0.5.8;
                  
                  /**
                   * @title Helps contracts guard against reentrancy attacks.
                   * @author Remco Bloemen <remco@2π.com>, Eenae <[email protected]>
                   * @dev If you mark a function `nonReentrant`, you should also
                   * mark it `external`.
                   */
                  contract ReentrancyGuard {
                      /// @dev counter to allow mutex lock with only one SSTORE operation
                      uint256 private _guardCounter;
                  
                      constructor () internal {
                          // The counter starts at one to prevent changing it from zero to a non-zero
                          // value, which is a more expensive operation.
                          _guardCounter = 1;
                      }
                  
                      /**
                       * @dev Prevents a contract from calling itself, directly or indirectly.
                       * Calling a `nonReentrant` function from another `nonReentrant`
                       * function is not supported. It is possible to prevent this from happening
                       * by making the `nonReentrant` function external, and make it call a
                       * `private` function that does the actual work.
                       */
                      modifier nonReentrant() {
                          _guardCounter += 1;
                          uint256 localCounter = _guardCounter;
                          _;
                          require(localCounter == _guardCounter, "re-entered");
                      }
                  }
                  
                  // File: contracts/InterestRateModel.sol
                  
                  pragma solidity ^0.5.8;
                  
                  /**
                    * @title The Compound InterestRateModel Interface
                    * @author Compound
                    * @notice Any interest rate model should derive from this contract.
                    * @dev These functions are specifically not marked `pure` as implementations of this
                    *      contract may read from storage variables.
                    */
                  interface InterestRateModel {
                      /**
                        * @notice Gets the current borrow interest rate based on the given asset, total cash, total borrows
                        *         and total reserves.
                        * @dev The return value should be scaled by 1e18, thus a return value of
                        *      `(true, 1000000000000)` implies an interest rate of 0.000001 or 0.0001% *per block*.
                        * @param cash The total cash of the underlying asset in the CToken
                        * @param borrows The total borrows of the underlying asset in the CToken
                        * @param reserves The total reserves of the underlying asset in the CToken
                        * @return Success or failure and the borrow interest rate per block scaled by 10e18
                        */
                      function getBorrowRate(uint cash, uint borrows, uint reserves) external view returns (uint, uint);
                  
                      /**
                        * @notice Marker function used for light validation when updating the interest rate model of a market
                        * @dev Marker function used for light validation when updating the interest rate model of a market. Implementations should simply return true.
                        * @return Success or failure
                        */
                      function isInterestRateModel() external view returns (bool);
                  }
                  
                  // File: contracts/CToken.sol
                  
                  pragma solidity ^0.5.8;
                  
                  
                  
                  
                  
                  
                  
                  
                  /**
                   * @title Compound's CToken Contract
                   * @notice Abstract base for CTokens
                   * @author Compound
                   */
                  contract CToken is EIP20Interface, Exponential, TokenErrorReporter, ReentrancyGuard {
                      /**
                       * @notice Indicator that this is a CToken contract (for inspection)
                       */
                      bool public constant isCToken = true;
                  
                      /**
                       * @notice EIP-20 token name for this token
                       */
                      string public name;
                  
                      /**
                       * @notice EIP-20 token symbol for this token
                       */
                      string public symbol;
                  
                      /**
                       * @notice EIP-20 token decimals for this token
                       */
                      uint public decimals;
                  
                      /**
                       * @notice Maximum borrow rate that can ever be applied (.0005% / block)
                       */
                      uint constant borrowRateMaxMantissa = 5e14;
                  
                      /**
                       * @notice Maximum fraction of interest that can be set aside for reserves
                       */
                      uint constant reserveFactorMaxMantissa = 1e18;
                  
                      /**
                       * @notice Administrator for this contract
                       */
                      address payable public admin;
                  
                      /**
                       * @notice Pending administrator for this contract
                       */
                      address payable public pendingAdmin;
                  
                      /**
                       * @notice Contract which oversees inter-cToken operations
                       */
                      ComptrollerInterface public comptroller;
                  
                      /**
                       * @notice Model which tells what the current interest rate should be
                       */
                      InterestRateModel public interestRateModel;
                  
                      /**
                       * @notice Initial exchange rate used when minting the first CTokens (used when totalSupply = 0)
                       */
                      uint public initialExchangeRateMantissa;
                  
                      /**
                       * @notice Fraction of interest currently set aside for reserves
                       */
                      uint public reserveFactorMantissa;
                  
                      /**
                       * @notice Block number that interest was last accrued at
                       */
                      uint public accrualBlockNumber;
                  
                      /**
                       * @notice Accumulator of total earned interest since the opening of the market
                       */
                      uint public borrowIndex;
                  
                      /**
                       * @notice Total amount of outstanding borrows of the underlying in this market
                       */
                      uint public totalBorrows;
                  
                      /**
                       * @notice Total amount of reserves of the underlying held in this market
                       */
                      uint public totalReserves;
                  
                      /**
                       * @notice Total number of tokens in circulation
                       */
                      uint256 public totalSupply;
                  
                      /**
                       * @notice Official record of token balances for each account
                       */
                      mapping (address => uint256) accountTokens;
                  
                      /**
                       * @notice Approved token transfer amounts on behalf of others
                       */
                      mapping (address => mapping (address => uint256)) transferAllowances;
                  
                      /**
                       * @notice Container for borrow balance information
                       * @member principal Total balance (with accrued interest), after applying the most recent balance-changing action
                       * @member interestIndex Global borrowIndex as of the most recent balance-changing action
                       */
                      struct BorrowSnapshot {
                          uint principal;
                          uint interestIndex;
                      }
                  
                      /**
                       * @notice Mapping of account addresses to outstanding borrow balances
                       */
                      mapping(address => BorrowSnapshot) accountBorrows;
                  
                  
                      /*** Market Events ***/
                  
                      /**
                       * @notice Event emitted when interest is accrued
                       */
                      event AccrueInterest(uint interestAccumulated, uint borrowIndex, uint totalBorrows);
                  
                      /**
                       * @notice Event emitted when tokens are minted
                       */
                      event Mint(address minter, uint mintAmount, uint mintTokens);
                  
                      /**
                       * @notice Event emitted when tokens are redeemed
                       */
                      event Redeem(address redeemer, uint redeemAmount, uint redeemTokens);
                  
                      /**
                       * @notice Event emitted when underlying is borrowed
                       */
                      event Borrow(address borrower, uint borrowAmount, uint accountBorrows, uint totalBorrows);
                  
                      /**
                       * @notice Event emitted when a borrow is repaid
                       */
                      event RepayBorrow(address payer, address borrower, uint repayAmount, uint accountBorrows, uint totalBorrows);
                  
                      /**
                       * @notice Event emitted when a borrow is liquidated
                       */
                      event LiquidateBorrow(address liquidator, address borrower, uint repayAmount, address cTokenCollateral, uint seizeTokens);
                  
                  
                      /*** Admin Events ***/
                  
                      /**
                       * @notice Event emitted when pendingAdmin is changed
                       */
                      event NewPendingAdmin(address oldPendingAdmin, address newPendingAdmin);
                  
                      /**
                       * @notice Event emitted when pendingAdmin is accepted, which means admin is updated
                       */
                      event NewAdmin(address oldAdmin, address newAdmin);
                  
                      /**
                       * @notice Event emitted when comptroller is changed
                       */
                      event NewComptroller(ComptrollerInterface oldComptroller, ComptrollerInterface newComptroller);
                  
                      /**
                       * @notice Event emitted when interestRateModel is changed
                       */
                      event NewMarketInterestRateModel(InterestRateModel oldInterestRateModel, InterestRateModel newInterestRateModel);
                  
                      /**
                       * @notice Event emitted when the reserve factor is changed
                       */
                      event NewReserveFactor(uint oldReserveFactorMantissa, uint newReserveFactorMantissa);
                  
                      /**
                       * @notice Event emitted when the reserves are reduced
                       */
                      event ReservesReduced(address admin, uint reduceAmount, uint newTotalReserves);
                  
                  
                      /**
                       * @notice Construct a new money market
                       * @param comptroller_ The address of the Comptroller
                       * @param interestRateModel_ The address of the interest rate model
                       * @param initialExchangeRateMantissa_ The initial exchange rate, scaled by 1e18
                       * @param name_ EIP-20 name of this token
                       * @param symbol_ EIP-20 symbol of this token
                       * @param decimals_ EIP-20 decimal precision of this token
                       */
                      constructor(ComptrollerInterface comptroller_,
                                  InterestRateModel interestRateModel_,
                                  uint initialExchangeRateMantissa_,
                                  string memory name_,
                                  string memory symbol_,
                                  uint decimals_) internal {
                          // Set admin to msg.sender
                          admin = msg.sender;
                  
                          // Set initial exchange rate
                          initialExchangeRateMantissa = initialExchangeRateMantissa_;
                          require(initialExchangeRateMantissa > 0, "Initial exchange rate must be greater than zero.");
                  
                          // Set the comptroller
                          uint err = _setComptroller(comptroller_);
                          require(err == uint(Error.NO_ERROR), "Setting comptroller failed");
                  
                          // Initialize block number and borrow index (block number mocks depend on comptroller being set)
                          accrualBlockNumber = getBlockNumber();
                          borrowIndex = mantissaOne;
                  
                          // Set the interest rate model (depends on block number / borrow index)
                          err = _setInterestRateModelFresh(interestRateModel_);
                          require(err == uint(Error.NO_ERROR), "Setting interest rate model failed");
                  
                          name = name_;
                          symbol = symbol_;
                          decimals = decimals_;
                      }
                  
                      /**
                       * @notice Transfer `tokens` tokens from `src` to `dst` by `spender`
                       * @dev Called by both `transfer` and `transferFrom` internally
                       * @param spender The address of the account performing the transfer
                       * @param src The address of the source account
                       * @param dst The address of the destination account
                       * @param tokens The number of tokens to transfer
                       * @return Whether or not the transfer succeeded
                       */
                      function transferTokens(address spender, address src, address dst, uint tokens) internal returns (uint) {
                          /* Fail if transfer not allowed */
                          uint allowed = comptroller.transferAllowed(address(this), src, dst, tokens);
                          if (allowed != 0) {
                              return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.TRANSFER_COMPTROLLER_REJECTION, allowed);
                          }
                  
                          /* Do not allow self-transfers */
                          if (src == dst) {
                              return fail(Error.BAD_INPUT, FailureInfo.TRANSFER_NOT_ALLOWED);
                          }
                  
                          /* Get the allowance, infinite for the account owner */
                          uint startingAllowance = 0;
                          if (spender == src) {
                              startingAllowance = uint(-1);
                          } else {
                              startingAllowance = transferAllowances[src][spender];
                          }
                  
                          /* Do the calculations, checking for {under,over}flow */
                          MathError mathErr;
                          uint allowanceNew;
                          uint srcTokensNew;
                          uint dstTokensNew;
                  
                          (mathErr, allowanceNew) = subUInt(startingAllowance, tokens);
                          if (mathErr != MathError.NO_ERROR) {
                              return fail(Error.MATH_ERROR, FailureInfo.TRANSFER_NOT_ALLOWED);
                          }
                  
                          (mathErr, srcTokensNew) = subUInt(accountTokens[src], tokens);
                          if (mathErr != MathError.NO_ERROR) {
                              return fail(Error.MATH_ERROR, FailureInfo.TRANSFER_NOT_ENOUGH);
                          }
                  
                          (mathErr, dstTokensNew) = addUInt(accountTokens[dst], tokens);
                          if (mathErr != MathError.NO_ERROR) {
                              return fail(Error.MATH_ERROR, FailureInfo.TRANSFER_TOO_MUCH);
                          }
                  
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                  
                          accountTokens[src] = srcTokensNew;
                          accountTokens[dst] = dstTokensNew;
                  
                          /* Eat some of the allowance (if necessary) */
                          if (startingAllowance != uint(-1)) {
                              transferAllowances[src][spender] = allowanceNew;
                          }
                  
                          /* We emit a Transfer event */
                          emit Transfer(src, dst, tokens);
                  
                          /* We call the defense hook (which checks for under-collateralization) */
                          comptroller.transferVerify(address(this), src, dst, tokens);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice Transfer `amount` tokens from `msg.sender` to `dst`
                       * @param dst The address of the destination account
                       * @param amount The number of tokens to transfer
                       * @return Whether or not the transfer succeeded
                       */
                      function transfer(address dst, uint256 amount) external nonReentrant returns (bool) {
                          return transferTokens(msg.sender, msg.sender, dst, amount) == uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice Transfer `amount` tokens from `src` to `dst`
                       * @param src The address of the source account
                       * @param dst The address of the destination account
                       * @param amount The number of tokens to transfer
                       * @return Whether or not the transfer succeeded
                       */
                      function transferFrom(address src, address dst, uint256 amount) external nonReentrant returns (bool) {
                          return transferTokens(msg.sender, src, dst, amount) == uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice Approve `spender` to transfer up to `amount` from `src`
                       * @dev This will overwrite the approval amount for `spender`
                       *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
                       * @param spender The address of the account which may transfer tokens
                       * @param amount The number of tokens that are approved (-1 means infinite)
                       * @return Whether or not the approval succeeded
                       */
                      function approve(address spender, uint256 amount) external returns (bool) {
                          address src = msg.sender;
                          transferAllowances[src][spender] = amount;
                          emit Approval(src, spender, amount);
                          return true;
                      }
                  
                      /**
                       * @notice Get the current allowance from `owner` for `spender`
                       * @param owner The address of the account which owns the tokens to be spent
                       * @param spender The address of the account which may transfer tokens
                       * @return The number of tokens allowed to be spent (-1 means infinite)
                       */
                      function allowance(address owner, address spender) external view returns (uint256) {
                          return transferAllowances[owner][spender];
                      }
                  
                      /**
                       * @notice Get the token balance of the `owner`
                       * @param owner The address of the account to query
                       * @return The number of tokens owned by `owner`
                       */
                      function balanceOf(address owner) external view returns (uint256) {
                          return accountTokens[owner];
                      }
                  
                      /**
                       * @notice Get the underlying balance of the `owner`
                       * @dev This also accrues interest in a transaction
                       * @param owner The address of the account to query
                       * @return The amount of underlying owned by `owner`
                       */
                      function balanceOfUnderlying(address owner) external returns (uint) {
                          Exp memory exchangeRate = Exp({mantissa: exchangeRateCurrent()});
                          (MathError mErr, uint balance) = mulScalarTruncate(exchangeRate, accountTokens[owner]);
                          require(mErr == MathError.NO_ERROR);
                          return balance;
                      }
                  
                      /**
                       * @notice Get a snapshot of the account's balances, and the cached exchange rate
                       * @dev This is used by comptroller to more efficiently perform liquidity checks.
                       * @param account Address of the account to snapshot
                       * @return (possible error, token balance, borrow balance, exchange rate mantissa)
                       */
                      function getAccountSnapshot(address account) external view returns (uint, uint, uint, uint) {
                          uint cTokenBalance = accountTokens[account];
                          uint borrowBalance;
                          uint exchangeRateMantissa;
                  
                          MathError mErr;
                  
                          (mErr, borrowBalance) = borrowBalanceStoredInternal(account);
                          if (mErr != MathError.NO_ERROR) {
                              return (uint(Error.MATH_ERROR), 0, 0, 0);
                          }
                  
                          (mErr, exchangeRateMantissa) = exchangeRateStoredInternal();
                          if (mErr != MathError.NO_ERROR) {
                              return (uint(Error.MATH_ERROR), 0, 0, 0);
                          }
                  
                          return (uint(Error.NO_ERROR), cTokenBalance, borrowBalance, exchangeRateMantissa);
                      }
                  
                      /**
                       * @dev Function to simply retrieve block number
                       *  This exists mainly for inheriting test contracts to stub this result.
                       */
                      function getBlockNumber() internal view returns (uint) {
                          return block.number;
                      }
                  
                      /**
                       * @notice Returns the current per-block borrow interest rate for this cToken
                       * @return The borrow interest rate per block, scaled by 1e18
                       */
                      function borrowRatePerBlock() external view returns (uint) {
                          (uint opaqueErr, uint borrowRateMantissa) = interestRateModel.getBorrowRate(getCashPrior(), totalBorrows, totalReserves);
                          require(opaqueErr == 0, "borrowRatePerBlock: interestRateModel.borrowRate failed"); // semi-opaque
                          return borrowRateMantissa;
                      }
                  
                      /**
                       * @notice Returns the current per-block supply interest rate for this cToken
                       * @return The supply interest rate per block, scaled by 1e18
                       */
                      function supplyRatePerBlock() external view returns (uint) {
                          /* We calculate the supply rate:
                           *  underlying = totalSupply × exchangeRate
                           *  borrowsPer = totalBorrows ÷ underlying
                           *  supplyRate = borrowRate × (1-reserveFactor) × borrowsPer
                           */
                          uint exchangeRateMantissa = exchangeRateStored();
                  
                          (uint e0, uint borrowRateMantissa) = interestRateModel.getBorrowRate(getCashPrior(), totalBorrows, totalReserves);
                          require(e0 == 0, "supplyRatePerBlock: calculating borrowRate failed"); // semi-opaque
                  
                          (MathError e1, Exp memory underlying) = mulScalar(Exp({mantissa: exchangeRateMantissa}), totalSupply);
                          require(e1 == MathError.NO_ERROR, "supplyRatePerBlock: calculating underlying failed");
                  
                          (MathError e2, Exp memory borrowsPer) = divScalarByExp(totalBorrows, underlying);
                          require(e2 == MathError.NO_ERROR, "supplyRatePerBlock: calculating borrowsPer failed");
                  
                          (MathError e3, Exp memory oneMinusReserveFactor) = subExp(Exp({mantissa: mantissaOne}), Exp({mantissa: reserveFactorMantissa}));
                          require(e3 == MathError.NO_ERROR, "supplyRatePerBlock: calculating oneMinusReserveFactor failed");
                  
                          (MathError e4, Exp memory supplyRate) = mulExp3(Exp({mantissa: borrowRateMantissa}), oneMinusReserveFactor, borrowsPer);
                          require(e4 == MathError.NO_ERROR, "supplyRatePerBlock: calculating supplyRate failed");
                  
                          return supplyRate.mantissa;
                      }
                  
                      /**
                       * @notice Returns the current total borrows plus accrued interest
                       * @return The total borrows with interest
                       */
                      function totalBorrowsCurrent() external nonReentrant returns (uint) {
                          require(accrueInterest() == uint(Error.NO_ERROR), "accrue interest failed");
                          return totalBorrows;
                      }
                  
                      /**
                       * @notice Accrue interest to updated borrowIndex and then calculate account's borrow balance using the updated borrowIndex
                       * @param account The address whose balance should be calculated after updating borrowIndex
                       * @return The calculated balance
                       */
                      function borrowBalanceCurrent(address account) external nonReentrant returns (uint) {
                          require(accrueInterest() == uint(Error.NO_ERROR), "accrue interest failed");
                          return borrowBalanceStored(account);
                      }
                  
                      /**
                       * @notice Return the borrow balance of account based on stored data
                       * @param account The address whose balance should be calculated
                       * @return The calculated balance
                       */
                      function borrowBalanceStored(address account) public view returns (uint) {
                          (MathError err, uint result) = borrowBalanceStoredInternal(account);
                          require(err == MathError.NO_ERROR, "borrowBalanceStored: borrowBalanceStoredInternal failed");
                          return result;
                      }
                  
                      /**
                       * @notice Return the borrow balance of account based on stored data
                       * @param account The address whose balance should be calculated
                       * @return (error code, the calculated balance or 0 if error code is non-zero)
                       */
                      function borrowBalanceStoredInternal(address account) internal view returns (MathError, uint) {
                          /* Note: we do not assert that the market is up to date */
                          MathError mathErr;
                          uint principalTimesIndex;
                          uint result;
                  
                          /* Get borrowBalance and borrowIndex */
                          BorrowSnapshot storage borrowSnapshot = accountBorrows[account];
                  
                          /* If borrowBalance = 0 then borrowIndex is likely also 0.
                           * Rather than failing the calculation with a division by 0, we immediately return 0 in this case.
                           */
                          if (borrowSnapshot.principal == 0) {
                              return (MathError.NO_ERROR, 0);
                          }
                  
                          /* Calculate new borrow balance using the interest index:
                           *  recentBorrowBalance = borrower.borrowBalance * market.borrowIndex / borrower.borrowIndex
                           */
                          (mathErr, principalTimesIndex) = mulUInt(borrowSnapshot.principal, borrowIndex);
                          if (mathErr != MathError.NO_ERROR) {
                              return (mathErr, 0);
                          }
                  
                          (mathErr, result) = divUInt(principalTimesIndex, borrowSnapshot.interestIndex);
                          if (mathErr != MathError.NO_ERROR) {
                              return (mathErr, 0);
                          }
                  
                          return (MathError.NO_ERROR, result);
                      }
                  
                      /**
                       * @notice Accrue interest then return the up-to-date exchange rate
                       * @return Calculated exchange rate scaled by 1e18
                       */
                      function exchangeRateCurrent() public nonReentrant returns (uint) {
                          require(accrueInterest() == uint(Error.NO_ERROR), "accrue interest failed");
                          return exchangeRateStored();
                      }
                  
                      /**
                       * @notice Calculates the exchange rate from the underlying to the CToken
                       * @dev This function does not accrue interest before calculating the exchange rate
                       * @return Calculated exchange rate scaled by 1e18
                       */
                      function exchangeRateStored() public view returns (uint) {
                          (MathError err, uint result) = exchangeRateStoredInternal();
                          require(err == MathError.NO_ERROR, "exchangeRateStored: exchangeRateStoredInternal failed");
                          return result;
                      }
                  
                      /**
                       * @notice Calculates the exchange rate from the underlying to the CToken
                       * @dev This function does not accrue interest before calculating the exchange rate
                       * @return (error code, calculated exchange rate scaled by 1e18)
                       */
                      function exchangeRateStoredInternal() internal view returns (MathError, uint) {
                          if (totalSupply == 0) {
                              /*
                               * If there are no tokens minted:
                               *  exchangeRate = initialExchangeRate
                               */
                              return (MathError.NO_ERROR, initialExchangeRateMantissa);
                          } else {
                              /*
                               * Otherwise:
                               *  exchangeRate = (totalCash + totalBorrows - totalReserves) / totalSupply
                               */
                              uint totalCash = getCashPrior();
                              uint cashPlusBorrowsMinusReserves;
                              Exp memory exchangeRate;
                              MathError mathErr;
                  
                              (mathErr, cashPlusBorrowsMinusReserves) = addThenSubUInt(totalCash, totalBorrows, totalReserves);
                              if (mathErr != MathError.NO_ERROR) {
                                  return (mathErr, 0);
                              }
                  
                              (mathErr, exchangeRate) = getExp(cashPlusBorrowsMinusReserves, totalSupply);
                              if (mathErr != MathError.NO_ERROR) {
                                  return (mathErr, 0);
                              }
                  
                              return (MathError.NO_ERROR, exchangeRate.mantissa);
                          }
                      }
                  
                      /**
                       * @notice Get cash balance of this cToken in the underlying asset
                       * @return The quantity of underlying asset owned by this contract
                       */
                      function getCash() external view returns (uint) {
                          return getCashPrior();
                      }
                  
                      struct AccrueInterestLocalVars {
                          MathError mathErr;
                          uint opaqueErr;
                          uint borrowRateMantissa;
                          uint currentBlockNumber;
                          uint blockDelta;
                  
                          Exp simpleInterestFactor;
                  
                          uint interestAccumulated;
                          uint totalBorrowsNew;
                          uint totalReservesNew;
                          uint borrowIndexNew;
                      }
                  
                      /**
                        * @notice Applies accrued interest to total borrows and reserves.
                        * @dev This calculates interest accrued from the last checkpointed block
                        *      up to the current block and writes new checkpoint to storage.
                        */
                      function accrueInterest() public returns (uint) {
                          AccrueInterestLocalVars memory vars;
                  
                          /* Calculate the current borrow interest rate */
                          (vars.opaqueErr, vars.borrowRateMantissa) = interestRateModel.getBorrowRate(getCashPrior(), totalBorrows, totalReserves);
                          require(vars.borrowRateMantissa <= borrowRateMaxMantissa, "borrow rate is absurdly high");
                          if (vars.opaqueErr != 0) {
                              return failOpaque(Error.INTEREST_RATE_MODEL_ERROR, FailureInfo.ACCRUE_INTEREST_BORROW_RATE_CALCULATION_FAILED, vars.opaqueErr);
                          }
                  
                          /* Remember the initial block number */
                          vars.currentBlockNumber = getBlockNumber();
                  
                          /* Calculate the number of blocks elapsed since the last accrual */
                          (vars.mathErr, vars.blockDelta) = subUInt(vars.currentBlockNumber, accrualBlockNumber);
                          assert(vars.mathErr == MathError.NO_ERROR); // Block delta should always succeed and if it doesn't, blow up.
                  
                          /*
                           * Calculate the interest accumulated into borrows and reserves and the new index:
                           *  simpleInterestFactor = borrowRate * blockDelta
                           *  interestAccumulated = simpleInterestFactor * totalBorrows
                           *  totalBorrowsNew = interestAccumulated + totalBorrows
                           *  totalReservesNew = interestAccumulated * reserveFactor + totalReserves
                           *  borrowIndexNew = simpleInterestFactor * borrowIndex + borrowIndex
                           */
                          (vars.mathErr, vars.simpleInterestFactor) = mulScalar(Exp({mantissa: vars.borrowRateMantissa}), vars.blockDelta);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_SIMPLE_INTEREST_FACTOR_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.interestAccumulated) = mulScalarTruncate(vars.simpleInterestFactor, totalBorrows);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_ACCUMULATED_INTEREST_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.totalBorrowsNew) = addUInt(vars.interestAccumulated, totalBorrows);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_NEW_TOTAL_BORROWS_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.totalReservesNew) = mulScalarTruncateAddUInt(Exp({mantissa: reserveFactorMantissa}), vars.interestAccumulated, totalReserves);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_NEW_TOTAL_RESERVES_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.borrowIndexNew) = mulScalarTruncateAddUInt(vars.simpleInterestFactor, borrowIndex, borrowIndex);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_NEW_BORROW_INDEX_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                  
                          /* We write the previously calculated values into storage */
                          accrualBlockNumber = vars.currentBlockNumber;
                          borrowIndex = vars.borrowIndexNew;
                          totalBorrows = vars.totalBorrowsNew;
                          totalReserves = vars.totalReservesNew;
                  
                          /* We emit an AccrueInterest event */
                          emit AccrueInterest(vars.interestAccumulated, vars.borrowIndexNew, totalBorrows);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice Sender supplies assets into the market and receives cTokens in exchange
                       * @dev Accrues interest whether or not the operation succeeds, unless reverted
                       * @param mintAmount The amount of the underlying asset to supply
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function mintInternal(uint mintAmount) internal nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
                              return fail(Error(error), FailureInfo.MINT_ACCRUE_INTEREST_FAILED);
                          }
                          // mintFresh emits the actual Mint event if successful and logs on errors, so we don't need to
                          return mintFresh(msg.sender, mintAmount);
                      }
                  
                      struct MintLocalVars {
                          Error err;
                          MathError mathErr;
                          uint exchangeRateMantissa;
                          uint mintTokens;
                          uint totalSupplyNew;
                          uint accountTokensNew;
                      }
                  
                      /**
                       * @notice User supplies assets into the market and receives cTokens in exchange
                       * @dev Assumes interest has already been accrued up to the current block
                       * @param minter The address of the account which is supplying the assets
                       * @param mintAmount The amount of the underlying asset to supply
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function mintFresh(address minter, uint mintAmount) internal returns (uint) {
                          /* Fail if mint not allowed */
                          uint allowed = comptroller.mintAllowed(address(this), minter, mintAmount);
                          if (allowed != 0) {
                              return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.MINT_COMPTROLLER_REJECTION, allowed);
                          }
                  
                          /* Verify market's block number equals current block number */
                          if (accrualBlockNumber != getBlockNumber()) {
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.MINT_FRESHNESS_CHECK);
                          }
                  
                          MintLocalVars memory vars;
                  
                          /* Fail if checkTransferIn fails */
                          vars.err = checkTransferIn(minter, mintAmount);
                          if (vars.err != Error.NO_ERROR) {
                              return fail(vars.err, FailureInfo.MINT_TRANSFER_IN_NOT_POSSIBLE);
                          }
                  
                          /*
                           * We get the current exchange rate and calculate the number of cTokens to be minted:
                           *  mintTokens = mintAmount / exchangeRate
                           */
                          (vars.mathErr, vars.exchangeRateMantissa) = exchangeRateStoredInternal();
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_EXCHANGE_RATE_READ_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.mintTokens) = divScalarByExpTruncate(mintAmount, Exp({mantissa: vars.exchangeRateMantissa}));
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_EXCHANGE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          /*
                           * We calculate the new total supply of cTokens and minter token balance, checking for overflow:
                           *  totalSupplyNew = totalSupply + mintTokens
                           *  accountTokensNew = accountTokens[minter] + mintTokens
                           */
                          (vars.mathErr, vars.totalSupplyNew) = addUInt(totalSupply, vars.mintTokens);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_NEW_TOTAL_SUPPLY_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.accountTokensNew) = addUInt(accountTokens[minter], vars.mintTokens);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                  
                          /*
                           * We call doTransferIn for the minter and the mintAmount
                           *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
                           *  On success, the cToken holds an additional mintAmount of cash.
                           *  If doTransferIn fails despite the fact we checked pre-conditions,
                           *   we revert because we can't be sure if side effects occurred.
                           */
                          vars.err = doTransferIn(minter, mintAmount);
                          if (vars.err != Error.NO_ERROR) {
                              return fail(vars.err, FailureInfo.MINT_TRANSFER_IN_FAILED);
                          }
                  
                          /* We write previously calculated values into storage */
                          totalSupply = vars.totalSupplyNew;
                          accountTokens[minter] = vars.accountTokensNew;
                  
                          /* We emit a Mint event, and a Transfer event */
                          emit Mint(minter, mintAmount, vars.mintTokens);
                          emit Transfer(address(this), minter, vars.mintTokens);
                  
                          /* We call the defense hook */
                          comptroller.mintVerify(address(this), minter, mintAmount, vars.mintTokens);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice Sender redeems cTokens in exchange for the underlying asset
                       * @dev Accrues interest whether or not the operation succeeds, unless reverted
                       * @param redeemTokens The number of cTokens to redeem into underlying
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function redeemInternal(uint redeemTokens) internal nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted redeem failed
                              return fail(Error(error), FailureInfo.REDEEM_ACCRUE_INTEREST_FAILED);
                          }
                          // redeemFresh emits redeem-specific logs on errors, so we don't need to
                          return redeemFresh(msg.sender, redeemTokens, 0);
                      }
                  
                      /**
                       * @notice Sender redeems cTokens in exchange for a specified amount of underlying asset
                       * @dev Accrues interest whether or not the operation succeeds, unless reverted
                       * @param redeemAmount The amount of underlying to redeem
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function redeemUnderlyingInternal(uint redeemAmount) internal nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted redeem failed
                              return fail(Error(error), FailureInfo.REDEEM_ACCRUE_INTEREST_FAILED);
                          }
                          // redeemFresh emits redeem-specific logs on errors, so we don't need to
                          return redeemFresh(msg.sender, 0, redeemAmount);
                      }
                  
                      struct RedeemLocalVars {
                          Error err;
                          MathError mathErr;
                          uint exchangeRateMantissa;
                          uint redeemTokens;
                          uint redeemAmount;
                          uint totalSupplyNew;
                          uint accountTokensNew;
                      }
                  
                      /**
                       * @notice User redeems cTokens in exchange for the underlying asset
                       * @dev Assumes interest has already been accrued up to the current block
                       * @param redeemer The address of the account which is redeeming the tokens
                       * @param redeemTokensIn The number of cTokens to redeem into underlying (only one of redeemTokensIn or redeemAmountIn may be zero)
                       * @param redeemAmountIn The number of cTokens to redeem into underlying (only one of redeemTokensIn or redeemAmountIn may be zero)
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function redeemFresh(address payable redeemer, uint redeemTokensIn, uint redeemAmountIn) internal returns (uint) {
                          require(redeemTokensIn == 0 || redeemAmountIn == 0, "one of redeemTokensIn or redeemAmountIn must be zero");
                  
                          RedeemLocalVars memory vars;
                  
                          /* exchangeRate = invoke Exchange Rate Stored() */
                          (vars.mathErr, vars.exchangeRateMantissa) = exchangeRateStoredInternal();
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_EXCHANGE_RATE_READ_FAILED, uint(vars.mathErr));
                          }
                  
                          /* If redeemTokensIn > 0: */
                          if (redeemTokensIn > 0) {
                              /*
                               * We calculate the exchange rate and the amount of underlying to be redeemed:
                               *  redeemTokens = redeemTokensIn
                               *  redeemAmount = redeemTokensIn x exchangeRateCurrent
                               */
                              vars.redeemTokens = redeemTokensIn;
                  
                              (vars.mathErr, vars.redeemAmount) = mulScalarTruncate(Exp({mantissa: vars.exchangeRateMantissa}), redeemTokensIn);
                              if (vars.mathErr != MathError.NO_ERROR) {
                                  return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_EXCHANGE_TOKENS_CALCULATION_FAILED, uint(vars.mathErr));
                              }
                          } else {
                              /*
                               * We get the current exchange rate and calculate the amount to be redeemed:
                               *  redeemTokens = redeemAmountIn / exchangeRate
                               *  redeemAmount = redeemAmountIn
                               */
                  
                              (vars.mathErr, vars.redeemTokens) = divScalarByExpTruncate(redeemAmountIn, Exp({mantissa: vars.exchangeRateMantissa}));
                              if (vars.mathErr != MathError.NO_ERROR) {
                                  return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_EXCHANGE_AMOUNT_CALCULATION_FAILED, uint(vars.mathErr));
                              }
                  
                              vars.redeemAmount = redeemAmountIn;
                          }
                  
                          /* Fail if redeem not allowed */
                          uint allowed = comptroller.redeemAllowed(address(this), redeemer, vars.redeemTokens);
                          if (allowed != 0) {
                              return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.REDEEM_COMPTROLLER_REJECTION, allowed);
                          }
                  
                          /* Verify market's block number equals current block number */
                          if (accrualBlockNumber != getBlockNumber()) {
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.REDEEM_FRESHNESS_CHECK);
                          }
                  
                          /*
                           * We calculate the new total supply and redeemer balance, checking for underflow:
                           *  totalSupplyNew = totalSupply - redeemTokens
                           *  accountTokensNew = accountTokens[redeemer] - redeemTokens
                           */
                          (vars.mathErr, vars.totalSupplyNew) = subUInt(totalSupply, vars.redeemTokens);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_NEW_TOTAL_SUPPLY_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.accountTokensNew) = subUInt(accountTokens[redeemer], vars.redeemTokens);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          /* Fail gracefully if protocol has insufficient cash */
                          if (getCashPrior() < vars.redeemAmount) {
                              return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.REDEEM_TRANSFER_OUT_NOT_POSSIBLE);
                          }
                  
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                  
                          /*
                           * We invoke doTransferOut for the redeemer and the redeemAmount.
                           *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
                           *  On success, the cToken has redeemAmount less of cash.
                           *  If doTransferOut fails despite the fact we checked pre-conditions,
                           *   we revert because we can't be sure if side effects occurred.
                           */
                          vars.err = doTransferOut(redeemer, vars.redeemAmount);
                          require(vars.err == Error.NO_ERROR, "redeem transfer out failed");
                  
                          /* We write previously calculated values into storage */
                          totalSupply = vars.totalSupplyNew;
                          accountTokens[redeemer] = vars.accountTokensNew;
                  
                          /* We emit a Transfer event, and a Redeem event */
                          emit Transfer(redeemer, address(this), vars.redeemTokens);
                          emit Redeem(redeemer, vars.redeemAmount, vars.redeemTokens);
                  
                          /* We call the defense hook */
                          comptroller.redeemVerify(address(this), redeemer, vars.redeemAmount, vars.redeemTokens);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                        * @notice Sender borrows assets from the protocol to their own address
                        * @param borrowAmount The amount of the underlying asset to borrow
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function borrowInternal(uint borrowAmount) internal nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
                              return fail(Error(error), FailureInfo.BORROW_ACCRUE_INTEREST_FAILED);
                          }
                          // borrowFresh emits borrow-specific logs on errors, so we don't need to
                          return borrowFresh(msg.sender, borrowAmount);
                      }
                  
                      struct BorrowLocalVars {
                          Error err;
                          MathError mathErr;
                          uint accountBorrows;
                          uint accountBorrowsNew;
                          uint totalBorrowsNew;
                      }
                  
                      /**
                        * @notice Users borrow assets from the protocol to their own address
                        * @param borrowAmount The amount of the underlying asset to borrow
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function borrowFresh(address payable borrower, uint borrowAmount) internal returns (uint) {
                          /* Fail if borrow not allowed */
                          uint allowed = comptroller.borrowAllowed(address(this), borrower, borrowAmount);
                          if (allowed != 0) {
                              return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.BORROW_COMPTROLLER_REJECTION, allowed);
                          }
                  
                          /* Verify market's block number equals current block number */
                          if (accrualBlockNumber != getBlockNumber()) {
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.BORROW_FRESHNESS_CHECK);
                          }
                  
                          /* Fail gracefully if protocol has insufficient underlying cash */
                          if (getCashPrior() < borrowAmount) {
                              return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.BORROW_CASH_NOT_AVAILABLE);
                          }
                  
                          BorrowLocalVars memory vars;
                  
                          /*
                           * We calculate the new borrower and total borrow balances, failing on overflow:
                           *  accountBorrowsNew = accountBorrows + borrowAmount
                           *  totalBorrowsNew = totalBorrows + borrowAmount
                           */
                          (vars.mathErr, vars.accountBorrows) = borrowBalanceStoredInternal(borrower);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.accountBorrowsNew) = addUInt(vars.accountBorrows, borrowAmount);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.totalBorrowsNew) = addUInt(totalBorrows, borrowAmount);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                  
                          /*
                           * We invoke doTransferOut for the borrower and the borrowAmount.
                           *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
                           *  On success, the cToken borrowAmount less of cash.
                           *  If doTransferOut fails despite the fact we checked pre-conditions,
                           *   we revert because we can't be sure if side effects occurred.
                           */
                          vars.err = doTransferOut(borrower, borrowAmount);
                          require(vars.err == Error.NO_ERROR, "borrow transfer out failed");
                  
                          /* We write the previously calculated values into storage */
                          accountBorrows[borrower].principal = vars.accountBorrowsNew;
                          accountBorrows[borrower].interestIndex = borrowIndex;
                          totalBorrows = vars.totalBorrowsNew;
                  
                          /* We emit a Borrow event */
                          emit Borrow(borrower, borrowAmount, vars.accountBorrowsNew, vars.totalBorrowsNew);
                  
                          /* We call the defense hook */
                          comptroller.borrowVerify(address(this), borrower, borrowAmount);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice Sender repays their own borrow
                       * @param repayAmount The amount to repay
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function repayBorrowInternal(uint repayAmount) internal nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
                              return fail(Error(error), FailureInfo.REPAY_BORROW_ACCRUE_INTEREST_FAILED);
                          }
                          // repayBorrowFresh emits repay-borrow-specific logs on errors, so we don't need to
                          return repayBorrowFresh(msg.sender, msg.sender, repayAmount);
                      }
                  
                      /**
                       * @notice Sender repays a borrow belonging to borrower
                       * @param borrower the account with the debt being payed off
                       * @param repayAmount The amount to repay
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function repayBorrowBehalfInternal(address borrower, uint repayAmount) internal nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
                              return fail(Error(error), FailureInfo.REPAY_BEHALF_ACCRUE_INTEREST_FAILED);
                          }
                          // repayBorrowFresh emits repay-borrow-specific logs on errors, so we don't need to
                          return repayBorrowFresh(msg.sender, borrower, repayAmount);
                      }
                  
                      struct RepayBorrowLocalVars {
                          Error err;
                          MathError mathErr;
                          uint repayAmount;
                          uint borrowerIndex;
                          uint accountBorrows;
                          uint accountBorrowsNew;
                          uint totalBorrowsNew;
                      }
                  
                      /**
                       * @notice Borrows are repaid by another user (possibly the borrower).
                       * @param payer the account paying off the borrow
                       * @param borrower the account with the debt being payed off
                       * @param repayAmount the amount of undelrying tokens being returned
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function repayBorrowFresh(address payer, address borrower, uint repayAmount) internal returns (uint) {
                          /* Fail if repayBorrow not allowed */
                          uint allowed = comptroller.repayBorrowAllowed(address(this), payer, borrower, repayAmount);
                          if (allowed != 0) {
                              return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.REPAY_BORROW_COMPTROLLER_REJECTION, allowed);
                          }
                  
                          /* Verify market's block number equals current block number */
                          if (accrualBlockNumber != getBlockNumber()) {
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.REPAY_BORROW_FRESHNESS_CHECK);
                          }
                  
                          RepayBorrowLocalVars memory vars;
                  
                          /* We remember the original borrowerIndex for verification purposes */
                          vars.borrowerIndex = accountBorrows[borrower].interestIndex;
                  
                          /* We fetch the amount the borrower owes, with accumulated interest */
                          (vars.mathErr, vars.accountBorrows) = borrowBalanceStoredInternal(borrower);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.REPAY_BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          /* If repayAmount == -1, repayAmount = accountBorrows */
                          if (repayAmount == uint(-1)) {
                              vars.repayAmount = vars.accountBorrows;
                          } else {
                              vars.repayAmount = repayAmount;
                          }
                  
                          /* Fail if checkTransferIn fails */
                          vars.err = checkTransferIn(payer, vars.repayAmount);
                          if (vars.err != Error.NO_ERROR) {
                              return fail(vars.err, FailureInfo.REPAY_BORROW_TRANSFER_IN_NOT_POSSIBLE);
                          }
                  
                          /*
                           * We calculate the new borrower and total borrow balances, failing on underflow:
                           *  accountBorrowsNew = accountBorrows - repayAmount
                           *  totalBorrowsNew = totalBorrows - repayAmount
                           */
                          (vars.mathErr, vars.accountBorrowsNew) = subUInt(vars.accountBorrows, vars.repayAmount);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.REPAY_BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.totalBorrowsNew) = subUInt(totalBorrows, vars.repayAmount);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.REPAY_BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                  
                          /*
                           * We call doTransferIn for the payer and the repayAmount
                           *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
                           *  On success, the cToken holds an additional repayAmount of cash.
                           *  If doTransferIn fails despite the fact we checked pre-conditions,
                           *   we revert because we can't be sure if side effects occurred.
                           */
                          vars.err = doTransferIn(payer, vars.repayAmount);
                          require(vars.err == Error.NO_ERROR, "repay borrow transfer in failed");
                  
                          /* We write the previously calculated values into storage */
                          accountBorrows[borrower].principal = vars.accountBorrowsNew;
                          accountBorrows[borrower].interestIndex = borrowIndex;
                          totalBorrows = vars.totalBorrowsNew;
                  
                          /* We emit a RepayBorrow event */
                          emit RepayBorrow(payer, borrower, vars.repayAmount, vars.accountBorrowsNew, vars.totalBorrowsNew);
                  
                          /* We call the defense hook */
                          comptroller.repayBorrowVerify(address(this), payer, borrower, vars.repayAmount, vars.borrowerIndex);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice The sender liquidates the borrowers collateral.
                       *  The collateral seized is transferred to the liquidator.
                       * @param borrower The borrower of this cToken to be liquidated
                       * @param cTokenCollateral The market in which to seize collateral from the borrower
                       * @param repayAmount The amount of the underlying borrowed asset to repay
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function liquidateBorrowInternal(address borrower, uint repayAmount, CToken cTokenCollateral) internal nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted liquidation failed
                              return fail(Error(error), FailureInfo.LIQUIDATE_ACCRUE_BORROW_INTEREST_FAILED);
                          }
                  
                          error = cTokenCollateral.accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted liquidation failed
                              return fail(Error(error), FailureInfo.LIQUIDATE_ACCRUE_COLLATERAL_INTEREST_FAILED);
                          }
                  
                          // liquidateBorrowFresh emits borrow-specific logs on errors, so we don't need to
                          return liquidateBorrowFresh(msg.sender, borrower, repayAmount, cTokenCollateral);
                      }
                  
                      /**
                       * @notice The liquidator liquidates the borrowers collateral.
                       *  The collateral seized is transferred to the liquidator.
                       * @param borrower The borrower of this cToken to be liquidated
                       * @param liquidator The address repaying the borrow and seizing collateral
                       * @param cTokenCollateral The market in which to seize collateral from the borrower
                       * @param repayAmount The amount of the underlying borrowed asset to repay
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function liquidateBorrowFresh(address liquidator, address borrower, uint repayAmount, CToken cTokenCollateral) internal returns (uint) {
                          /* Fail if liquidate not allowed */
                          uint allowed = comptroller.liquidateBorrowAllowed(address(this), address(cTokenCollateral), liquidator, borrower, repayAmount);
                          if (allowed != 0) {
                              return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.LIQUIDATE_COMPTROLLER_REJECTION, allowed);
                          }
                  
                          /* Verify market's block number equals current block number */
                          if (accrualBlockNumber != getBlockNumber()) {
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.LIQUIDATE_FRESHNESS_CHECK);
                          }
                  
                          /* Verify cTokenCollateral market's block number equals current block number */
                          if (cTokenCollateral.accrualBlockNumber() != getBlockNumber()) {
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.LIQUIDATE_COLLATERAL_FRESHNESS_CHECK);
                          }
                  
                          /* Fail if borrower = liquidator */
                          if (borrower == liquidator) {
                              return fail(Error.INVALID_ACCOUNT_PAIR, FailureInfo.LIQUIDATE_LIQUIDATOR_IS_BORROWER);
                          }
                  
                          /* Fail if repayAmount = 0 */
                          if (repayAmount == 0) {
                              return fail(Error.INVALID_CLOSE_AMOUNT_REQUESTED, FailureInfo.LIQUIDATE_CLOSE_AMOUNT_IS_ZERO);
                          }
                  
                          /* Fail if repayAmount = -1 */
                          if (repayAmount == uint(-1)) {
                              return fail(Error.INVALID_CLOSE_AMOUNT_REQUESTED, FailureInfo.LIQUIDATE_CLOSE_AMOUNT_IS_UINT_MAX);
                          }
                  
                          /* We calculate the number of collateral tokens that will be seized */
                          (uint amountSeizeError, uint seizeTokens) = comptroller.liquidateCalculateSeizeTokens(address(this), address(cTokenCollateral), repayAmount);
                          if (amountSeizeError != 0) {
                              return failOpaque(Error.COMPTROLLER_CALCULATION_ERROR, FailureInfo.LIQUIDATE_COMPTROLLER_CALCULATE_AMOUNT_SEIZE_FAILED, amountSeizeError);
                          }
                  
                          /* Fail if seizeTokens > borrower collateral token balance */
                          if (seizeTokens > cTokenCollateral.balanceOf(borrower)) {
                              return fail(Error.TOKEN_INSUFFICIENT_BALANCE, FailureInfo.LIQUIDATE_SEIZE_TOO_MUCH);
                          }
                  
                          /* Fail if repayBorrow fails */
                          uint repayBorrowError = repayBorrowFresh(liquidator, borrower, repayAmount);
                          if (repayBorrowError != uint(Error.NO_ERROR)) {
                              return fail(Error(repayBorrowError), FailureInfo.LIQUIDATE_REPAY_BORROW_FRESH_FAILED);
                          }
                  
                          /* Revert if seize tokens fails (since we cannot be sure of side effects) */
                          uint seizeError = cTokenCollateral.seize(liquidator, borrower, seizeTokens);
                          require(seizeError == uint(Error.NO_ERROR), "token seizure failed");
                  
                          /* We emit a LiquidateBorrow event */
                          emit LiquidateBorrow(liquidator, borrower, repayAmount, address(cTokenCollateral), seizeTokens);
                  
                          /* We call the defense hook */
                          comptroller.liquidateBorrowVerify(address(this), address(cTokenCollateral), liquidator, borrower, repayAmount, seizeTokens);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice Transfers collateral tokens (this market) to the liquidator.
                       * @dev Will fail unless called by another cToken during the process of liquidation.
                       *  Its absolutely critical to use msg.sender as the borrowed cToken and not a parameter.
                       * @param liquidator The account receiving seized collateral
                       * @param borrower The account having collateral seized
                       * @param seizeTokens The number of cTokens to seize
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function seize(address liquidator, address borrower, uint seizeTokens) external nonReentrant returns (uint) {
                          /* Fail if seize not allowed */
                          uint allowed = comptroller.seizeAllowed(address(this), msg.sender, liquidator, borrower, seizeTokens);
                          if (allowed != 0) {
                              return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.LIQUIDATE_SEIZE_COMPTROLLER_REJECTION, allowed);
                          }
                  
                          /* Fail if borrower = liquidator */
                          if (borrower == liquidator) {
                              return fail(Error.INVALID_ACCOUNT_PAIR, FailureInfo.LIQUIDATE_SEIZE_LIQUIDATOR_IS_BORROWER);
                          }
                  
                          MathError mathErr;
                          uint borrowerTokensNew;
                          uint liquidatorTokensNew;
                  
                          /*
                           * We calculate the new borrower and liquidator token balances, failing on underflow/overflow:
                           *  borrowerTokensNew = accountTokens[borrower] - seizeTokens
                           *  liquidatorTokensNew = accountTokens[liquidator] + seizeTokens
                           */
                          (mathErr, borrowerTokensNew) = subUInt(accountTokens[borrower], seizeTokens);
                          if (mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.LIQUIDATE_SEIZE_BALANCE_DECREMENT_FAILED, uint(mathErr));
                          }
                  
                          (mathErr, liquidatorTokensNew) = addUInt(accountTokens[liquidator], seizeTokens);
                          if (mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.LIQUIDATE_SEIZE_BALANCE_INCREMENT_FAILED, uint(mathErr));
                          }
                  
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                  
                          /* We write the previously calculated values into storage */
                          accountTokens[borrower] = borrowerTokensNew;
                          accountTokens[liquidator] = liquidatorTokensNew;
                  
                          /* Emit a Transfer event */
                          emit Transfer(borrower, liquidator, seizeTokens);
                  
                          /* We call the defense hook */
                          comptroller.seizeVerify(address(this), msg.sender, liquidator, borrower, seizeTokens);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                  
                      /*** Admin Functions ***/
                  
                      /**
                        * @notice Begins transfer of admin rights. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
                        * @dev Admin function to begin change of admin. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
                        * @param newPendingAdmin New pending admin.
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        *
                        * TODO: Should we add a second arg to verify, like a checksum of `newAdmin` address?
                        */
                      function _setPendingAdmin(address payable newPendingAdmin) external returns (uint) {
                          // Check caller = admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_PENDING_ADMIN_OWNER_CHECK);
                          }
                  
                          // Save current value, if any, for inclusion in log
                          address oldPendingAdmin = pendingAdmin;
                  
                          // Store pendingAdmin with value newPendingAdmin
                          pendingAdmin = newPendingAdmin;
                  
                          // Emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin)
                          emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                        * @notice Accepts transfer of admin rights. msg.sender must be pendingAdmin
                        * @dev Admin function for pending admin to accept role and update admin
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function _acceptAdmin() external returns (uint) {
                          // Check caller is pendingAdmin and pendingAdmin ≠ address(0)
                          if (msg.sender != pendingAdmin || msg.sender == address(0)) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.ACCEPT_ADMIN_PENDING_ADMIN_CHECK);
                          }
                  
                          // Save current values for inclusion in log
                          address oldAdmin = admin;
                          address oldPendingAdmin = pendingAdmin;
                  
                          // Store admin with value pendingAdmin
                          admin = pendingAdmin;
                  
                          // Clear the pending value
                          pendingAdmin = address(0);
                  
                          emit NewAdmin(oldAdmin, admin);
                          emit NewPendingAdmin(oldPendingAdmin, pendingAdmin);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                        * @notice Sets a new comptroller for the market
                        * @dev Admin function to set a new comptroller
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function _setComptroller(ComptrollerInterface newComptroller) public returns (uint) {
                          // Check caller is admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_COMPTROLLER_OWNER_CHECK);
                          }
                  
                          ComptrollerInterface oldComptroller = comptroller;
                          // Ensure invoke comptroller.isComptroller() returns true
                          require(newComptroller.isComptroller(), "marker method returned false");
                  
                          // Set market's comptroller to newComptroller
                          comptroller = newComptroller;
                  
                          // Emit NewComptroller(oldComptroller, newComptroller)
                          emit NewComptroller(oldComptroller, newComptroller);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                        * @notice accrues interest and sets a new reserve factor for the protocol using _setReserveFactorFresh
                        * @dev Admin function to accrue interest and set a new reserve factor
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function _setReserveFactor(uint newReserveFactorMantissa) external nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted reserve factor change failed.
                              return fail(Error(error), FailureInfo.SET_RESERVE_FACTOR_ACCRUE_INTEREST_FAILED);
                          }
                          // _setReserveFactorFresh emits reserve-factor-specific logs on errors, so we don't need to.
                          return _setReserveFactorFresh(newReserveFactorMantissa);
                      }
                  
                      /**
                        * @notice Sets a new reserve factor for the protocol (*requires fresh interest accrual)
                        * @dev Admin function to set a new reserve factor
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function _setReserveFactorFresh(uint newReserveFactorMantissa) internal returns (uint) {
                          // Check caller is admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_RESERVE_FACTOR_ADMIN_CHECK);
                          }
                  
                          // Verify market's block number equals current block number
                          if (accrualBlockNumber != getBlockNumber()) {
                              // TODO: static_assert + no error code?
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.SET_RESERVE_FACTOR_FRESH_CHECK);
                          }
                  
                          // Check newReserveFactor ≤ maxReserveFactor
                          if (newReserveFactorMantissa > reserveFactorMaxMantissa) {
                              return fail(Error.BAD_INPUT, FailureInfo.SET_RESERVE_FACTOR_BOUNDS_CHECK);
                          }
                  
                          uint oldReserveFactorMantissa = reserveFactorMantissa;
                          reserveFactorMantissa = newReserveFactorMantissa;
                  
                          emit NewReserveFactor(oldReserveFactorMantissa, newReserveFactorMantissa);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice Accrues interest and reduces reserves by transferring to admin
                       * @param reduceAmount Amount of reduction to reserves
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function _reduceReserves(uint reduceAmount) external nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted reduce reserves failed.
                              return fail(Error(error), FailureInfo.REDUCE_RESERVES_ACCRUE_INTEREST_FAILED);
                          }
                          // _reduceReservesFresh emits reserve-reduction-specific logs on errors, so we don't need to.
                          return _reduceReservesFresh(reduceAmount);
                      }
                  
                      /**
                       * @notice Reduces reserves by transferring to admin
                       * @dev Requires fresh interest accrual
                       * @param reduceAmount Amount of reduction to reserves
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function _reduceReservesFresh(uint reduceAmount) internal returns (uint) {
                          Error err;
                          // totalReserves - reduceAmount
                          uint totalReservesNew;
                  
                          // Check caller is admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.REDUCE_RESERVES_ADMIN_CHECK);
                          }
                  
                          // We fail gracefully unless market's block number equals current block number
                          if (accrualBlockNumber != getBlockNumber()) {
                              // TODO: static_assert + no error code?
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.REDUCE_RESERVES_FRESH_CHECK);
                          }
                  
                          // Fail gracefully if protocol has insufficient underlying cash
                          if (getCashPrior() < reduceAmount) {
                              return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.REDUCE_RESERVES_CASH_NOT_AVAILABLE);
                          }
                  
                          // Check reduceAmount ≤ reserves[n] (totalReserves)
                          // TODO: I'm following the spec literally here but I think we should we just use SafeMath instead and fail on an error (which would be underflow)
                          if (reduceAmount > totalReserves) {
                              return fail(Error.BAD_INPUT, FailureInfo.REDUCE_RESERVES_VALIDATION);
                          }
                  
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                  
                          totalReservesNew = totalReserves - reduceAmount;
                          // We checked reduceAmount <= totalReserves above, so this should never revert.
                          require(totalReservesNew <= totalReserves, "reduce reserves unexpected underflow");
                  
                          // Store reserves[n+1] = reserves[n] - reduceAmount
                          totalReserves = totalReservesNew;
                  
                          // invoke doTransferOut(reduceAmount, admin)
                          err = doTransferOut(admin, reduceAmount);
                          // we revert on the failure of this command
                          require(err == Error.NO_ERROR, "reduce reserves transfer out failed");
                  
                          emit ReservesReduced(admin, reduceAmount, totalReservesNew);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice accrues interest and updates the interest rate model using _setInterestRateModelFresh
                       * @dev Admin function to accrue interest and update the interest rate model
                       * @param newInterestRateModel the new interest rate model to use
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function _setInterestRateModel(InterestRateModel newInterestRateModel) public returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted change of interest rate model failed
                              return fail(Error(error), FailureInfo.SET_INTEREST_RATE_MODEL_ACCRUE_INTEREST_FAILED);
                          }
                          // _setInterestRateModelFresh emits interest-rate-model-update-specific logs on errors, so we don't need to.
                          return _setInterestRateModelFresh(newInterestRateModel);
                      }
                  
                      /**
                       * @notice updates the interest rate model (*requires fresh interest accrual)
                       * @dev Admin function to update the interest rate model
                       * @param newInterestRateModel the new interest rate model to use
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function _setInterestRateModelFresh(InterestRateModel newInterestRateModel) internal returns (uint) {
                  
                          // Used to store old model for use in the event that is emitted on success
                          InterestRateModel oldInterestRateModel;
                  
                          // Check caller is admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_INTEREST_RATE_MODEL_OWNER_CHECK);
                          }
                  
                          // We fail gracefully unless market's block number equals current block number
                          if (accrualBlockNumber != getBlockNumber()) {
                              // TODO: static_assert + no error code?
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.SET_INTEREST_RATE_MODEL_FRESH_CHECK);
                          }
                  
                          // Track the market's current interest rate model
                          oldInterestRateModel = interestRateModel;
                  
                          // Ensure invoke newInterestRateModel.isInterestRateModel() returns true
                          require(newInterestRateModel.isInterestRateModel(), "marker method returned false");
                  
                          // Set the interest rate model to newInterestRateModel
                          interestRateModel = newInterestRateModel;
                  
                          // Emit NewMarketInterestRateModel(oldInterestRateModel, newInterestRateModel)
                          emit NewMarketInterestRateModel(oldInterestRateModel, newInterestRateModel);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /*** Safe Token ***/
                  
                      /**
                       * @notice Gets balance of this contract in terms of the underlying
                       * @dev This excludes the value of the current message, if any
                       * @return The quantity of underlying owned by this contract
                       */
                      function getCashPrior() internal view returns (uint);
                  
                      /**
                       * @dev Checks whether or not there is sufficient allowance for this contract to move amount from `from` and
                       *      whether or not `from` has a balance of at least `amount`. Does NOT do a transfer.
                       */
                      function checkTransferIn(address from, uint amount) internal view returns (Error);
                  
                      /**
                       * @dev Performs a transfer in, ideally returning an explanatory error code upon failure rather than reverting.
                       *  If caller has not called `checkTransferIn`, this may revert due to insufficient balance or insufficient allowance.
                       *  If caller has called `checkTransferIn` successfully, this should not revert in normal conditions.
                       */
                      function doTransferIn(address from, uint amount) internal returns (Error);
                  
                      /**
                       * @dev Performs a transfer out, ideally returning an explanatory error code upon failure tather than reverting.
                       *  If caller has not called checked protocol's balance, may revert due to insufficient cash held in the contract.
                       *  If caller has checked protocol's balance, and verified it is >= amount, this should not revert in normal conditions.
                       */
                      function doTransferOut(address payable to, uint amount) internal returns (Error);
                  }
                  
                  // File: contracts/CErc20.sol
                  
                  pragma solidity ^0.5.8;
                  
                  
                  /**
                   * @title Compound's CErc20 Contract
                   * @notice CTokens which wrap an EIP-20 underlying
                   * @author Compound
                   */
                  contract CErc20 is CToken {
                  
                      /**
                       * @notice Underlying asset for this CToken
                       */
                      address public underlying;
                  
                      /**
                       * @notice Construct a new money market
                       * @param underlying_ The address of the underlying asset
                       * @param comptroller_ The address of the Comptroller
                       * @param interestRateModel_ The address of the interest rate model
                       * @param initialExchangeRateMantissa_ The initial exchange rate, scaled by 1e18
                       * @param name_ ERC-20 name of this token
                       * @param symbol_ ERC-20 symbol of this token
                       * @param decimals_ ERC-20 decimal precision of this token
                       */
                      constructor(address underlying_,
                                  ComptrollerInterface comptroller_,
                                  InterestRateModel interestRateModel_,
                                  uint initialExchangeRateMantissa_,
                                  string memory name_,
                                  string memory symbol_,
                                  uint decimals_) public
                      CToken(comptroller_, interestRateModel_, initialExchangeRateMantissa_, name_, symbol_, decimals_) {
                          // Set underlying
                          underlying = underlying_;
                          EIP20Interface(underlying).totalSupply(); // Sanity check the underlying
                      }
                  
                      /*** User Interface ***/
                  
                      /**
                       * @notice Sender supplies assets into the market and receives cTokens in exchange
                       * @dev Accrues interest whether or not the operation succeeds, unless reverted
                       * @param mintAmount The amount of the underlying asset to supply
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function mint(uint mintAmount) external returns (uint) {
                          return mintInternal(mintAmount);
                      }
                  
                      /**
                       * @notice Sender redeems cTokens in exchange for the underlying asset
                       * @dev Accrues interest whether or not the operation succeeds, unless reverted
                       * @param redeemTokens The number of cTokens to redeem into underlying
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function redeem(uint redeemTokens) external returns (uint) {
                          return redeemInternal(redeemTokens);
                      }
                  
                      /**
                       * @notice Sender redeems cTokens in exchange for a specified amount of underlying asset
                       * @dev Accrues interest whether or not the operation succeeds, unless reverted
                       * @param redeemAmount The amount of underlying to redeem
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function redeemUnderlying(uint redeemAmount) external returns (uint) {
                          return redeemUnderlyingInternal(redeemAmount);
                      }
                  
                      /**
                        * @notice Sender borrows assets from the protocol to their own address
                        * @param borrowAmount The amount of the underlying asset to borrow
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function borrow(uint borrowAmount) external returns (uint) {
                          return borrowInternal(borrowAmount);
                      }
                  
                      /**
                       * @notice Sender repays their own borrow
                       * @param repayAmount The amount to repay
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function repayBorrow(uint repayAmount) external returns (uint) {
                          return repayBorrowInternal(repayAmount);
                      }
                  
                      /**
                       * @notice Sender repays a borrow belonging to borrower
                       * @param borrower the account with the debt being payed off
                       * @param repayAmount The amount to repay
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function repayBorrowBehalf(address borrower, uint repayAmount) external returns (uint) {
                          return repayBorrowBehalfInternal(borrower, repayAmount);
                      }
                  
                      /**
                       * @notice The sender liquidates the borrowers collateral.
                       *  The collateral seized is transferred to the liquidator.
                       * @param borrower The borrower of this cToken to be liquidated
                       * @param cTokenCollateral The market in which to seize collateral from the borrower
                       * @param repayAmount The amount of the underlying borrowed asset to repay
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function liquidateBorrow(address borrower, uint repayAmount, CToken cTokenCollateral) external returns (uint) {
                          return liquidateBorrowInternal(borrower, repayAmount, cTokenCollateral);
                      }
                  
                      /*** Safe Token ***/
                  
                      /**
                       * @notice Gets balance of this contract in terms of the underlying
                       * @dev This excludes the value of the current message, if any
                       * @return The quantity of underlying tokens owned by this contract
                       */
                      function getCashPrior() internal view returns (uint) {
                          EIP20Interface token = EIP20Interface(underlying);
                          return token.balanceOf(address(this));
                      }
                  
                      /**
                       * @dev Checks whether or not there is sufficient allowance for this contract to move amount from `from` and
                       *      whether or not `from` has a balance of at least `amount`. Does NOT do a transfer.
                       */
                      function checkTransferIn(address from, uint amount) internal view returns (Error) {
                          EIP20Interface token = EIP20Interface(underlying);
                  
                          if (token.allowance(from, address(this)) < amount) {
                              return Error.TOKEN_INSUFFICIENT_ALLOWANCE;
                          }
                  
                          if (token.balanceOf(from) < amount) {
                              return Error.TOKEN_INSUFFICIENT_BALANCE;
                          }
                  
                          return Error.NO_ERROR;
                      }
                  
                      /**
                       * @dev Similar to EIP20 transfer, except it handles a False result from `transferFrom` and returns an explanatory
                       *      error code rather than reverting.  If caller has not called `checkTransferIn`, this may revert due to
                       *      insufficient balance or insufficient allowance. If caller has called `checkTransferIn` prior to this call,
                       *      and it returned Error.NO_ERROR, this should not revert in normal conditions.
                       *
                       *      Note: This wrapper safely handles non-standard ERC-20 tokens that do not return a value.
                       *            See here: https://medium.com/coinmonks/missing-return-value-bug-at-least-130-tokens-affected-d67bf08521ca
                       */
                      function doTransferIn(address from, uint amount) internal returns (Error) {
                          EIP20NonStandardInterface token = EIP20NonStandardInterface(underlying);
                          bool result;
                  
                          token.transferFrom(from, address(this), amount);
                  
                          // solium-disable-next-line security/no-inline-assembly
                          assembly {
                              switch returndatasize()
                                  case 0 {                      // This is a non-standard ERC-20
                                      result := not(0)          // set result to true
                                  }
                                  case 32 {                     // This is a complaint ERC-20
                                      returndatacopy(0, 0, 32)
                                      result := mload(0)        // Set `result = returndata` of external call
                                  }
                                  default {                     // This is an excessively non-compliant ERC-20, revert.
                                      revert(0, 0)
                                  }
                          }
                  
                          if (!result) {
                              return Error.TOKEN_TRANSFER_IN_FAILED;
                          }
                  
                          return Error.NO_ERROR;
                      }
                  
                      /**
                       * @dev Similar to EIP20 transfer, except it handles a False result from `transfer` and returns an explanatory
                       *      error code rather than reverting. If caller has not called checked protocol's balance, this may revert due to
                       *      insufficient cash held in this contract. If caller has checked protocol's balance prior to this call, and verified
                       *      it is >= amount, this should not revert in normal conditions.
                       *
                       *      Note: This wrapper safely handles non-standard ERC-20 tokens that do not return a value.
                       *            See here: https://medium.com/coinmonks/missing-return-value-bug-at-least-130-tokens-affected-d67bf08521ca
                       */
                      function doTransferOut(address payable to, uint amount) internal returns (Error) {
                          EIP20NonStandardInterface token = EIP20NonStandardInterface(underlying);
                          bool result;
                  
                          token.transfer(to, amount);
                  
                          // solium-disable-next-line security/no-inline-assembly
                          assembly {
                              switch returndatasize()
                                  case 0 {                      // This is a non-standard ERC-20
                                      result := not(0)          // set result to true
                                  }
                                  case 32 {                     // This is a complaint ERC-20
                                      returndatacopy(0, 0, 32)
                                      result := mload(0)        // Set `result = returndata` of external call
                                  }
                                  default {                     // This is an excessively non-compliant ERC-20, revert.
                                      revert(0, 0)
                                  }
                          }
                  
                          if (!result) {
                              return Error.TOKEN_TRANSFER_OUT_FAILED;
                          }
                  
                          return Error.NO_ERROR;
                      }
                  }
                  

                  File 2 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 3 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);
                  }
                  

                  File 4 of 6: LegacyJumpRateModelV2
                  pragma solidity ^0.5.16;
                  import "./SafeMath.sol";
                  /**
                    * @title Logic for Compound's JumpRateModel Contract V2.
                    * @author Compound (modified by Dharma Labs, refactored by Arr00)
                    * @notice Version 2 modifies Version 1 by enabling updateable parameters.
                    */
                  contract BaseJumpRateModelV2 {
                      using SafeMath for uint;
                      event NewInterestParams(uint baseRatePerBlock, uint multiplierPerBlock, uint jumpMultiplierPerBlock, uint kink);
                      /**
                       * @notice The address of the owner, i.e. the Timelock contract, which can update parameters directly
                       */
                      address public owner;
                      /**
                       * @notice The approximate number of blocks per year that is assumed by the interest rate model
                       */
                      uint public constant blocksPerYear = 2102400;
                      /**
                       * @notice The multiplier of utilization rate that gives the slope of the interest rate
                       */
                      uint public multiplierPerBlock;
                      /**
                       * @notice The base interest rate which is the y-intercept when utilization rate is 0
                       */
                      uint public baseRatePerBlock;
                      /**
                       * @notice The multiplierPerBlock after hitting a specified utilization point
                       */
                      uint public jumpMultiplierPerBlock;
                      /**
                       * @notice The utilization point at which the jump multiplier is applied
                       */
                      uint public kink;
                      /**
                       * @notice Construct an interest rate model
                       * @param baseRatePerYear The approximate target base APR, as a mantissa (scaled by 1e18)
                       * @param multiplierPerYear The rate of increase in interest rate wrt utilization (scaled by 1e18)
                       * @param jumpMultiplierPerYear The multiplierPerBlock after hitting a specified utilization point
                       * @param kink_ The utilization point at which the jump multiplier is applied
                       * @param owner_ The address of the owner, i.e. the Timelock contract (which has the ability to update parameters directly)
                       */
                      constructor(uint baseRatePerYear, uint multiplierPerYear, uint jumpMultiplierPerYear, uint kink_, address owner_) internal {
                          owner = owner_;
                          updateJumpRateModelInternal(baseRatePerYear,  multiplierPerYear, jumpMultiplierPerYear, kink_);
                      }
                      /**
                       * @notice Update the parameters of the interest rate model (only callable by owner, i.e. Timelock)
                       * @param baseRatePerYear The approximate target base APR, as a mantissa (scaled by 1e18)
                       * @param multiplierPerYear The rate of increase in interest rate wrt utilization (scaled by 1e18)
                       * @param jumpMultiplierPerYear The multiplierPerBlock after hitting a specified utilization point
                       * @param kink_ The utilization point at which the jump multiplier is applied
                       */
                      function updateJumpRateModel(uint baseRatePerYear, uint multiplierPerYear, uint jumpMultiplierPerYear, uint kink_) external {
                          require(msg.sender == owner, "only the owner may call this function.");
                          updateJumpRateModelInternal(baseRatePerYear, multiplierPerYear, jumpMultiplierPerYear, kink_);
                      }
                      /**
                       * @notice Calculates the utilization rate of the market: `borrows / (cash + borrows - reserves)`
                       * @param cash The amount of cash in the market
                       * @param borrows The amount of borrows in the market
                       * @param reserves The amount of reserves in the market (currently unused)
                       * @return The utilization rate as a mantissa between [0, 1e18]
                       */
                      function utilizationRate(uint cash, uint borrows, uint reserves) public pure returns (uint) {
                          // Utilization rate is 0 when there are no borrows
                          if (borrows == 0) {
                              return 0;
                          }
                          return borrows.mul(1e18).div(cash.add(borrows).sub(reserves));
                      }
                      /**
                       * @notice Calculates the current borrow rate per block, with the error code expected by the market
                       * @param cash The amount of cash in the market
                       * @param borrows The amount of borrows in the market
                       * @param reserves The amount of reserves in the market
                       * @return The borrow rate percentage per block as a mantissa (scaled by 1e18)
                       */
                      function getBorrowRateInternal(uint cash, uint borrows, uint reserves) internal view returns (uint) {
                          uint util = utilizationRate(cash, borrows, reserves);
                          if (util <= kink) {
                              return util.mul(multiplierPerBlock).div(1e18).add(baseRatePerBlock);
                          } else {
                              uint normalRate = kink.mul(multiplierPerBlock).div(1e18).add(baseRatePerBlock);
                              uint excessUtil = util.sub(kink);
                              return excessUtil.mul(jumpMultiplierPerBlock).div(1e18).add(normalRate);
                          }
                      }
                      /**
                       * @notice Calculates the current supply rate per block
                       * @param cash The amount of cash in the market
                       * @param borrows The amount of borrows in the market
                       * @param reserves The amount of reserves in the market
                       * @param reserveFactorMantissa The current reserve factor for the market
                       * @return The supply rate percentage per block as a mantissa (scaled by 1e18)
                       */
                      function getSupplyRate(uint cash, uint borrows, uint reserves, uint reserveFactorMantissa) public view returns (uint) {
                          uint oneMinusReserveFactor = uint(1e18).sub(reserveFactorMantissa);
                          uint borrowRate = getBorrowRateInternal(cash, borrows, reserves);
                          uint rateToPool = borrowRate.mul(oneMinusReserveFactor).div(1e18);
                          return utilizationRate(cash, borrows, reserves).mul(rateToPool).div(1e18);
                      }
                      /**
                       * @notice Internal function to update the parameters of the interest rate model
                       * @param baseRatePerYear The approximate target base APR, as a mantissa (scaled by 1e18)
                       * @param multiplierPerYear The rate of increase in interest rate wrt utilization (scaled by 1e18)
                       * @param jumpMultiplierPerYear The multiplierPerBlock after hitting a specified utilization point
                       * @param kink_ The utilization point at which the jump multiplier is applied
                       */
                      function updateJumpRateModelInternal(uint baseRatePerYear, uint multiplierPerYear, uint jumpMultiplierPerYear, uint kink_) internal {
                          baseRatePerBlock = baseRatePerYear.div(blocksPerYear);
                          multiplierPerBlock = (multiplierPerYear.mul(1e18)).div(blocksPerYear.mul(kink_));
                          jumpMultiplierPerBlock = jumpMultiplierPerYear.div(blocksPerYear);
                          kink = kink_;
                          emit NewInterestParams(baseRatePerBlock, multiplierPerBlock, jumpMultiplierPerBlock, kink);
                      }
                  }
                  pragma solidity ^0.5.16;
                  /**
                    * @title Compound's Legacy InterestRateModel Interface
                    * @author Compound (modified by Arr00)
                    */
                  contract LegacyInterestRateModel {
                      /// @notice Indicator that this is an InterestRateModel contract (for inspection)
                      bool public constant isInterestRateModel = true;
                      /**
                        * @notice Calculates the current borrow interest rate per block
                        * @param cash The total amount of cash the market has
                        * @param borrows The total amount of borrows the market has outstanding
                        * @param reserves The total amount of reserves the market has
                        * @return error code (0 = no error), The borrow rate per block (as a percentage, and scaled by 1e18)
                        */
                      function getBorrowRate(uint cash, uint borrows, uint reserves) external view returns (uint,uint);
                      /**
                        * @notice Calculates the current supply interest rate per block
                        * @param cash The total amount of cash the market has
                        * @param borrows The total amount of borrows the market has outstanding
                        * @param reserves The total amount of reserves the market has
                        * @param reserveFactorMantissa The current reserve factor the market has
                        * @return The supply rate per block (as a percentage, and scaled by 1e18)
                        */
                      function getSupplyRate(uint cash, uint borrows, uint reserves, uint reserveFactorMantissa) external view returns (uint);
                  }
                  pragma solidity ^0.5.16;
                  import "./BaseJumpRateModelV2.sol";
                  import "./LegacyInterestRateModel.sol";
                  /**
                    * @title Compound's JumpRateModel Contract V2 for legacy cTokens
                    * @author Arr00
                    * @notice Supports only legacy cTokens
                    */
                  contract LegacyJumpRateModelV2 is LegacyInterestRateModel, BaseJumpRateModelV2  {
                  \t/**
                       * @notice Calculates the current borrow rate per block, with the error code expected by the market
                       * @param cash The amount of cash in the market
                       * @param borrows The amount of borrows in the market
                       * @param reserves The amount of reserves in the market
                       * @return (Error, The borrow rate percentage per block as a mantissa (scaled by 1e18))
                       */
                      function getBorrowRate(uint cash, uint borrows, uint reserves) external view returns (uint, uint) {
                          return (0,getBorrowRateInternal(cash, borrows, reserves));
                      }
                      
                      constructor(uint baseRatePerYear, uint multiplierPerYear, uint jumpMultiplierPerYear, uint kink_, address owner_) 
                      \tBaseJumpRateModelV2(baseRatePerYear,multiplierPerYear,jumpMultiplierPerYear,kink_,owner_) public {}
                  }
                  pragma solidity ^0.5.16;
                  // From https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/math/Math.sol
                  // Subject to the MIT license.
                  /**
                   * @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, 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 addition of two unsigned integers, reverting with custom message on overflow.
                       *
                       * Counterpart to Solidity's `+` operator.
                       *
                       * Requirements:
                       * - Addition cannot overflow.
                       */
                      function add(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
                          uint256 c = a + b;
                          require(c >= a, errorMessage);
                          return c;
                      }
                      /**
                       * @dev Returns the subtraction of two unsigned integers, reverting on underflow (when the result is negative).
                       *
                       * Counterpart to Solidity's `-` operator.
                       *
                       * Requirements:
                       * - Subtraction cannot underflow.
                       */
                      function sub(uint256 a, uint256 b) internal pure returns (uint256) {
                          return sub(a, b, "SafeMath: subtraction underflow");
                      }
                      /**
                       * @dev Returns the subtraction of two unsigned integers, reverting with custom message on underflow (when the result is negative).
                       *
                       * Counterpart to Solidity's `-` operator.
                       *
                       * Requirements:
                       * - Subtraction cannot underflow.
                       */
                      function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
                          require(b <= a, errorMessage);
                          uint256 c = a - b;
                          return c;
                      }
                      /**
                       * @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) {
                          // 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 0;
                          }
                          uint256 c = a * b;
                          require(c / a == b, "SafeMath: multiplication overflow");
                          return c;
                      }
                      /**
                       * @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, string memory errorMessage) internal pure returns (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 0;
                          }
                          uint256 c = a * b;
                          require(c / a == b, errorMessage);
                          return c;
                      }
                      /**
                       * @dev Returns the integer division of two unsigned integers.
                       * Reverts 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) {
                          return div(a, b, "SafeMath: division by zero");
                      }
                      /**
                       * @dev Returns the integer division of two unsigned integers.
                       * Reverts with custom message on division by zero. The result is rounded towards zero.
                       *
                       * Counterpart to Solidity's `/` operator. Note: this function uses a
                       * `revert` opcode (which leaves remaining gas untouched) while Solidity
                       * uses an invalid opcode to revert (consuming all remaining gas).
                       *
                       * Requirements:
                       * - The divisor cannot be zero.
                       */
                      function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
                          // Solidity only automatically asserts when dividing by 0
                          require(b > 0, errorMessage);
                          uint256 c = a / b;
                          // assert(a == b * c + a % b); // There is no case in which this doesn't hold
                          return c;
                      }
                      /**
                       * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
                       * Reverts when dividing by zero.
                       *
                       * Counterpart to Solidity's `%` operator. This function uses a `revert`
                       * opcode (which leaves remaining gas untouched) while Solidity uses an
                       * invalid opcode to revert (consuming all remaining gas).
                       *
                       * Requirements:
                       * - The divisor cannot be zero.
                       */
                      function mod(uint256 a, uint256 b) internal pure returns (uint256) {
                          return mod(a, b, "SafeMath: modulo by zero");
                      }
                      /**
                       * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
                       * Reverts with custom message 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, string memory errorMessage) internal pure returns (uint256) {
                          require(b != 0, errorMessage);
                          return a % b;
                      }
                  }
                  

                  File 5 of 6: Unitroller
                  // File: contracts/ErrorReporter.sol
                  
                  pragma solidity ^0.5.8;
                  
                  contract ComptrollerErrorReporter {
                      enum Error {
                          NO_ERROR,
                          UNAUTHORIZED,
                          COMPTROLLER_MISMATCH,
                          INSUFFICIENT_SHORTFALL,
                          INSUFFICIENT_LIQUIDITY,
                          INVALID_CLOSE_FACTOR,
                          INVALID_COLLATERAL_FACTOR,
                          INVALID_LIQUIDATION_INCENTIVE,
                          MARKET_NOT_ENTERED,
                          MARKET_NOT_LISTED,
                          MARKET_ALREADY_LISTED,
                          MATH_ERROR,
                          NONZERO_BORROW_BALANCE,
                          PRICE_ERROR,
                          REJECTION,
                          SNAPSHOT_ERROR,
                          TOO_MANY_ASSETS,
                          TOO_MUCH_REPAY
                      }
                  
                      enum FailureInfo {
                          ACCEPT_ADMIN_PENDING_ADMIN_CHECK,
                          ACCEPT_PENDING_IMPLEMENTATION_ADDRESS_CHECK,
                          EXIT_MARKET_BALANCE_OWED,
                          EXIT_MARKET_REJECTION,
                          SET_CLOSE_FACTOR_OWNER_CHECK,
                          SET_CLOSE_FACTOR_VALIDATION,
                          SET_COLLATERAL_FACTOR_OWNER_CHECK,
                          SET_COLLATERAL_FACTOR_NO_EXISTS,
                          SET_COLLATERAL_FACTOR_VALIDATION,
                          SET_COLLATERAL_FACTOR_WITHOUT_PRICE,
                          SET_IMPLEMENTATION_OWNER_CHECK,
                          SET_LIQUIDATION_INCENTIVE_OWNER_CHECK,
                          SET_LIQUIDATION_INCENTIVE_VALIDATION,
                          SET_MAX_ASSETS_OWNER_CHECK,
                          SET_PENDING_ADMIN_OWNER_CHECK,
                          SET_PENDING_IMPLEMENTATION_OWNER_CHECK,
                          SET_PRICE_ORACLE_OWNER_CHECK,
                          SUPPORT_MARKET_EXISTS,
                          SUPPORT_MARKET_OWNER_CHECK,
                          ZUNUSED
                      }
                  
                      /**
                        * @dev `error` corresponds to enum Error; `info` corresponds to enum FailureInfo, and `detail` is an arbitrary
                        * contract-specific code that enables us to report opaque error codes from upgradeable contracts.
                        **/
                      event Failure(uint error, uint info, uint detail);
                  
                      /**
                        * @dev use this when reporting a known error from the money market or a non-upgradeable collaborator
                        */
                      function fail(Error err, FailureInfo info) internal returns (uint) {
                          emit Failure(uint(err), uint(info), 0);
                  
                          return uint(err);
                      }
                  
                      /**
                        * @dev use this when reporting an opaque error from an upgradeable collaborator contract
                        */
                      function failOpaque(Error err, FailureInfo info, uint opaqueError) internal returns (uint) {
                          emit Failure(uint(err), uint(info), opaqueError);
                  
                          return uint(err);
                      }
                  }
                  
                  contract TokenErrorReporter {
                      enum Error {
                          NO_ERROR,
                          UNAUTHORIZED,
                          BAD_INPUT,
                          COMPTROLLER_REJECTION,
                          COMPTROLLER_CALCULATION_ERROR,
                          INTEREST_RATE_MODEL_ERROR,
                          INVALID_ACCOUNT_PAIR,
                          INVALID_CLOSE_AMOUNT_REQUESTED,
                          INVALID_COLLATERAL_FACTOR,
                          MATH_ERROR,
                          MARKET_NOT_FRESH,
                          MARKET_NOT_LISTED,
                          TOKEN_INSUFFICIENT_ALLOWANCE,
                          TOKEN_INSUFFICIENT_BALANCE,
                          TOKEN_INSUFFICIENT_CASH,
                          TOKEN_TRANSFER_IN_FAILED,
                          TOKEN_TRANSFER_OUT_FAILED
                      }
                  
                      /*
                       * Note: FailureInfo (but not Error) is kept in alphabetical order
                       *       This is because FailureInfo grows significantly faster, and
                       *       the order of Error has some meaning, while the order of FailureInfo
                       *       is entirely arbitrary.
                       */
                      enum FailureInfo {
                          ACCEPT_ADMIN_PENDING_ADMIN_CHECK,
                          ACCRUE_INTEREST_ACCUMULATED_INTEREST_CALCULATION_FAILED,
                          ACCRUE_INTEREST_BORROW_RATE_CALCULATION_FAILED,
                          ACCRUE_INTEREST_NEW_BORROW_INDEX_CALCULATION_FAILED,
                          ACCRUE_INTEREST_NEW_TOTAL_BORROWS_CALCULATION_FAILED,
                          ACCRUE_INTEREST_NEW_TOTAL_RESERVES_CALCULATION_FAILED,
                          ACCRUE_INTEREST_SIMPLE_INTEREST_FACTOR_CALCULATION_FAILED,
                          BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED,
                          BORROW_ACCRUE_INTEREST_FAILED,
                          BORROW_CASH_NOT_AVAILABLE,
                          BORROW_FRESHNESS_CHECK,
                          BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED,
                          BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED,
                          BORROW_MARKET_NOT_LISTED,
                          BORROW_COMPTROLLER_REJECTION,
                          LIQUIDATE_ACCRUE_BORROW_INTEREST_FAILED,
                          LIQUIDATE_ACCRUE_COLLATERAL_INTEREST_FAILED,
                          LIQUIDATE_COLLATERAL_FRESHNESS_CHECK,
                          LIQUIDATE_COMPTROLLER_REJECTION,
                          LIQUIDATE_COMPTROLLER_CALCULATE_AMOUNT_SEIZE_FAILED,
                          LIQUIDATE_CLOSE_AMOUNT_IS_UINT_MAX,
                          LIQUIDATE_CLOSE_AMOUNT_IS_ZERO,
                          LIQUIDATE_FRESHNESS_CHECK,
                          LIQUIDATE_LIQUIDATOR_IS_BORROWER,
                          LIQUIDATE_REPAY_BORROW_FRESH_FAILED,
                          LIQUIDATE_SEIZE_BALANCE_INCREMENT_FAILED,
                          LIQUIDATE_SEIZE_BALANCE_DECREMENT_FAILED,
                          LIQUIDATE_SEIZE_COMPTROLLER_REJECTION,
                          LIQUIDATE_SEIZE_LIQUIDATOR_IS_BORROWER,
                          LIQUIDATE_SEIZE_TOO_MUCH,
                          MINT_ACCRUE_INTEREST_FAILED,
                          MINT_COMPTROLLER_REJECTION,
                          MINT_EXCHANGE_CALCULATION_FAILED,
                          MINT_EXCHANGE_RATE_READ_FAILED,
                          MINT_FRESHNESS_CHECK,
                          MINT_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED,
                          MINT_NEW_TOTAL_SUPPLY_CALCULATION_FAILED,
                          MINT_TRANSFER_IN_FAILED,
                          MINT_TRANSFER_IN_NOT_POSSIBLE,
                          REDEEM_ACCRUE_INTEREST_FAILED,
                          REDEEM_COMPTROLLER_REJECTION,
                          REDEEM_EXCHANGE_TOKENS_CALCULATION_FAILED,
                          REDEEM_EXCHANGE_AMOUNT_CALCULATION_FAILED,
                          REDEEM_EXCHANGE_RATE_READ_FAILED,
                          REDEEM_FRESHNESS_CHECK,
                          REDEEM_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED,
                          REDEEM_NEW_TOTAL_SUPPLY_CALCULATION_FAILED,
                          REDEEM_TRANSFER_OUT_NOT_POSSIBLE,
                          REDUCE_RESERVES_ACCRUE_INTEREST_FAILED,
                          REDUCE_RESERVES_ADMIN_CHECK,
                          REDUCE_RESERVES_CASH_NOT_AVAILABLE,
                          REDUCE_RESERVES_FRESH_CHECK,
                          REDUCE_RESERVES_VALIDATION,
                          REPAY_BEHALF_ACCRUE_INTEREST_FAILED,
                          REPAY_BORROW_ACCRUE_INTEREST_FAILED,
                          REPAY_BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED,
                          REPAY_BORROW_COMPTROLLER_REJECTION,
                          REPAY_BORROW_FRESHNESS_CHECK,
                          REPAY_BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED,
                          REPAY_BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED,
                          REPAY_BORROW_TRANSFER_IN_NOT_POSSIBLE,
                          SET_COLLATERAL_FACTOR_OWNER_CHECK,
                          SET_COLLATERAL_FACTOR_VALIDATION,
                          SET_COMPTROLLER_OWNER_CHECK,
                          SET_INTEREST_RATE_MODEL_ACCRUE_INTEREST_FAILED,
                          SET_INTEREST_RATE_MODEL_FRESH_CHECK,
                          SET_INTEREST_RATE_MODEL_OWNER_CHECK,
                          SET_MAX_ASSETS_OWNER_CHECK,
                          SET_ORACLE_MARKET_NOT_LISTED,
                          SET_PENDING_ADMIN_OWNER_CHECK,
                          SET_RESERVE_FACTOR_ACCRUE_INTEREST_FAILED,
                          SET_RESERVE_FACTOR_ADMIN_CHECK,
                          SET_RESERVE_FACTOR_FRESH_CHECK,
                          SET_RESERVE_FACTOR_BOUNDS_CHECK,
                          TRANSFER_COMPTROLLER_REJECTION,
                          TRANSFER_NOT_ALLOWED,
                          TRANSFER_NOT_ENOUGH,
                          TRANSFER_TOO_MUCH
                      }
                  
                      /**
                        * @dev `error` corresponds to enum Error; `info` corresponds to enum FailureInfo, and `detail` is an arbitrary
                        * contract-specific code that enables us to report opaque error codes from upgradeable contracts.
                        **/
                      event Failure(uint error, uint info, uint detail);
                  
                      /**
                        * @dev use this when reporting a known error from the money market or a non-upgradeable collaborator
                        */
                      function fail(Error err, FailureInfo info) internal returns (uint) {
                          emit Failure(uint(err), uint(info), 0);
                  
                          return uint(err);
                      }
                  
                      /**
                        * @dev use this when reporting an opaque error from an upgradeable collaborator contract
                        */
                      function failOpaque(Error err, FailureInfo info, uint opaqueError) internal returns (uint) {
                          emit Failure(uint(err), uint(info), opaqueError);
                  
                          return uint(err);
                      }
                  }
                  
                  // File: contracts/ComptrollerInterface.sol
                  
                  pragma solidity ^0.5.8;
                  
                  interface ComptrollerInterface {
                      /**
                       * @notice Marker function used for light validation when updating the comptroller of a market
                       * @dev Implementations should simply return true.
                       * @return true
                       */
                      function isComptroller() external view returns (bool);
                  
                      /*** Assets You Are In ***/
                  
                      function enterMarkets(address[] calldata cTokens) external returns (uint[] memory);
                      function exitMarket(address cToken) external returns (uint);
                  
                      /*** Policy Hooks ***/
                  
                      function mintAllowed(address cToken, address minter, uint mintAmount) external returns (uint);
                      function mintVerify(address cToken, address minter, uint mintAmount, uint mintTokens) external;
                  
                      function redeemAllowed(address cToken, address redeemer, uint redeemTokens) external returns (uint);
                      function redeemVerify(address cToken, address redeemer, uint redeemAmount, uint redeemTokens) external;
                  
                      function borrowAllowed(address cToken, address borrower, uint borrowAmount) external returns (uint);
                      function borrowVerify(address cToken, address borrower, uint borrowAmount) external;
                  
                      function repayBorrowAllowed(
                          address cToken,
                          address payer,
                          address borrower,
                          uint repayAmount) external returns (uint);
                      function repayBorrowVerify(
                          address cToken,
                          address payer,
                          address borrower,
                          uint repayAmount,
                          uint borrowerIndex) external;
                  
                      function liquidateBorrowAllowed(
                          address cTokenBorrowed,
                          address cTokenCollateral,
                          address liquidator,
                          address borrower,
                          uint repayAmount) external returns (uint);
                      function liquidateBorrowVerify(
                          address cTokenBorrowed,
                          address cTokenCollateral,
                          address liquidator,
                          address borrower,
                          uint repayAmount,
                          uint seizeTokens) external;
                  
                      function seizeAllowed(
                          address cTokenCollateral,
                          address cTokenBorrowed,
                          address liquidator,
                          address borrower,
                          uint seizeTokens) external returns (uint);
                      function seizeVerify(
                          address cTokenCollateral,
                          address cTokenBorrowed,
                          address liquidator,
                          address borrower,
                          uint seizeTokens) external;
                  
                      function transferAllowed(address cToken, address src, address dst, uint transferTokens) external returns (uint);
                      function transferVerify(address cToken, address src, address dst, uint transferTokens) external;
                  
                      /*** Liquidity/Liquidation Calculations ***/
                  
                      function liquidateCalculateSeizeTokens(
                          address cTokenBorrowed,
                          address cTokenCollateral,
                          uint repayAmount) external view returns (uint, uint);
                  }
                  
                  // File: contracts/CarefulMath.sol
                  
                  pragma solidity ^0.5.8;
                  
                  /**
                    * @title Careful Math
                    * @author Compound
                    * @notice Derived from OpenZeppelin's SafeMath library
                    *         https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/math/SafeMath.sol
                    */
                  contract CarefulMath {
                  
                      /**
                       * @dev Possible error codes that we can return
                       */
                      enum MathError {
                          NO_ERROR,
                          DIVISION_BY_ZERO,
                          INTEGER_OVERFLOW,
                          INTEGER_UNDERFLOW
                      }
                  
                      /**
                      * @dev Multiplies two numbers, returns an error on overflow.
                      */
                      function mulUInt(uint a, uint b) internal pure returns (MathError, uint) {
                          if (a == 0) {
                              return (MathError.NO_ERROR, 0);
                          }
                  
                          uint c = a * b;
                  
                          if (c / a != b) {
                              return (MathError.INTEGER_OVERFLOW, 0);
                          } else {
                              return (MathError.NO_ERROR, c);
                          }
                      }
                  
                      /**
                      * @dev Integer division of two numbers, truncating the quotient.
                      */
                      function divUInt(uint a, uint b) internal pure returns (MathError, uint) {
                          if (b == 0) {
                              return (MathError.DIVISION_BY_ZERO, 0);
                          }
                  
                          return (MathError.NO_ERROR, a / b);
                      }
                  
                      /**
                      * @dev Subtracts two numbers, returns an error on overflow (i.e. if subtrahend is greater than minuend).
                      */
                      function subUInt(uint a, uint b) internal pure returns (MathError, uint) {
                          if (b <= a) {
                              return (MathError.NO_ERROR, a - b);
                          } else {
                              return (MathError.INTEGER_UNDERFLOW, 0);
                          }
                      }
                  
                      /**
                      * @dev Adds two numbers, returns an error on overflow.
                      */
                      function addUInt(uint a, uint b) internal pure returns (MathError, uint) {
                          uint c = a + b;
                  
                          if (c >= a) {
                              return (MathError.NO_ERROR, c);
                          } else {
                              return (MathError.INTEGER_OVERFLOW, 0);
                          }
                      }
                  
                      /**
                      * @dev add a and b and then subtract c
                      */
                      function addThenSubUInt(uint a, uint b, uint c) internal pure returns (MathError, uint) {
                          (MathError err0, uint sum) = addUInt(a, b);
                  
                          if (err0 != MathError.NO_ERROR) {
                              return (err0, 0);
                          }
                  
                          return subUInt(sum, c);
                      }
                  }
                  
                  // File: contracts/Exponential.sol
                  
                  pragma solidity ^0.5.8;
                  
                  
                  /**
                   * @title Exponential module for storing fixed-decision decimals
                   * @author Compound
                   * @notice Exp is a struct which stores decimals with a fixed precision of 18 decimal places.
                   *         Thus, if we wanted to store the 5.1, mantissa would store 5.1e18. That is:
                   *         `Exp({mantissa: 5100000000000000000})`.
                   */
                  contract Exponential is CarefulMath {
                      uint constant expScale = 1e18;
                      uint constant halfExpScale = expScale/2;
                      uint constant mantissaOne = expScale;
                  
                      struct Exp {
                          uint mantissa;
                      }
                  
                      /**
                       * @dev Creates an exponential from numerator and denominator values.
                       *      Note: Returns an error if (`num` * 10e18) > MAX_INT,
                       *            or if `denom` is zero.
                       */
                      function getExp(uint num, uint denom) pure internal returns (MathError, Exp memory) {
                          (MathError err0, uint scaledNumerator) = mulUInt(num, expScale);
                          if (err0 != MathError.NO_ERROR) {
                              return (err0, Exp({mantissa: 0}));
                          }
                  
                          (MathError err1, uint rational) = divUInt(scaledNumerator, denom);
                          if (err1 != MathError.NO_ERROR) {
                              return (err1, Exp({mantissa: 0}));
                          }
                  
                          return (MathError.NO_ERROR, Exp({mantissa: rational}));
                      }
                  
                      /**
                       * @dev Adds two exponentials, returning a new exponential.
                       */
                      function addExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
                          (MathError error, uint result) = addUInt(a.mantissa, b.mantissa);
                  
                          return (error, Exp({mantissa: result}));
                      }
                  
                      /**
                       * @dev Subtracts two exponentials, returning a new exponential.
                       */
                      function subExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
                          (MathError error, uint result) = subUInt(a.mantissa, b.mantissa);
                  
                          return (error, Exp({mantissa: result}));
                      }
                  
                      /**
                       * @dev Multiply an Exp by a scalar, returning a new Exp.
                       */
                      function mulScalar(Exp memory a, uint scalar) pure internal returns (MathError, Exp memory) {
                          (MathError err0, uint scaledMantissa) = mulUInt(a.mantissa, scalar);
                          if (err0 != MathError.NO_ERROR) {
                              return (err0, Exp({mantissa: 0}));
                          }
                  
                          return (MathError.NO_ERROR, Exp({mantissa: scaledMantissa}));
                      }
                  
                      /**
                       * @dev Multiply an Exp by a scalar, then truncate to return an unsigned integer.
                       */
                      function mulScalarTruncate(Exp memory a, uint scalar) pure internal returns (MathError, uint) {
                          (MathError err, Exp memory product) = mulScalar(a, scalar);
                          if (err != MathError.NO_ERROR) {
                              return (err, 0);
                          }
                  
                          return (MathError.NO_ERROR, truncate(product));
                      }
                  
                      /**
                       * @dev Multiply an Exp by a scalar, truncate, then add an to an unsigned integer, returning an unsigned integer.
                       */
                      function mulScalarTruncateAddUInt(Exp memory a, uint scalar, uint addend) pure internal returns (MathError, uint) {
                          (MathError err, Exp memory product) = mulScalar(a, scalar);
                          if (err != MathError.NO_ERROR) {
                              return (err, 0);
                          }
                  
                          return addUInt(truncate(product), addend);
                      }
                  
                      /**
                       * @dev Divide an Exp by a scalar, returning a new Exp.
                       */
                      function divScalar(Exp memory a, uint scalar) pure internal returns (MathError, Exp memory) {
                          (MathError err0, uint descaledMantissa) = divUInt(a.mantissa, scalar);
                          if (err0 != MathError.NO_ERROR) {
                              return (err0, Exp({mantissa: 0}));
                          }
                  
                          return (MathError.NO_ERROR, Exp({mantissa: descaledMantissa}));
                      }
                  
                      /**
                       * @dev Divide a scalar by an Exp, returning a new Exp.
                       */
                      function divScalarByExp(uint scalar, Exp memory divisor) pure internal returns (MathError, Exp memory) {
                          /*
                            We are doing this as:
                            getExp(mulUInt(expScale, scalar), divisor.mantissa)
                  
                            How it works:
                            Exp = a / b;
                            Scalar = s;
                            `s / (a / b)` = `b * s / a` and since for an Exp `a = mantissa, b = expScale`
                          */
                          (MathError err0, uint numerator) = mulUInt(expScale, scalar);
                          if (err0 != MathError.NO_ERROR) {
                              return (err0, Exp({mantissa: 0}));
                          }
                          return getExp(numerator, divisor.mantissa);
                      }
                  
                      /**
                       * @dev Divide a scalar by an Exp, then truncate to return an unsigned integer.
                       */
                      function divScalarByExpTruncate(uint scalar, Exp memory divisor) pure internal returns (MathError, uint) {
                          (MathError err, Exp memory fraction) = divScalarByExp(scalar, divisor);
                          if (err != MathError.NO_ERROR) {
                              return (err, 0);
                          }
                  
                          return (MathError.NO_ERROR, truncate(fraction));
                      }
                  
                      /**
                       * @dev Multiplies two exponentials, returning a new exponential.
                       */
                      function mulExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
                  
                          (MathError err0, uint doubleScaledProduct) = mulUInt(a.mantissa, b.mantissa);
                          if (err0 != MathError.NO_ERROR) {
                              return (err0, Exp({mantissa: 0}));
                          }
                  
                          // We add half the scale before dividing so that we get rounding instead of truncation.
                          //  See "Listing 6" and text above it at https://accu.org/index.php/journals/1717
                          // Without this change, a result like 6.6...e-19 will be truncated to 0 instead of being rounded to 1e-18.
                          (MathError err1, uint doubleScaledProductWithHalfScale) = addUInt(halfExpScale, doubleScaledProduct);
                          if (err1 != MathError.NO_ERROR) {
                              return (err1, Exp({mantissa: 0}));
                          }
                  
                          (MathError err2, uint product) = divUInt(doubleScaledProductWithHalfScale, expScale);
                          // The only error `div` can return is MathError.DIVISION_BY_ZERO but we control `expScale` and it is not zero.
                          assert(err2 == MathError.NO_ERROR);
                  
                          return (MathError.NO_ERROR, Exp({mantissa: product}));
                      }
                  
                      /**
                       * @dev Multiplies two exponentials given their mantissas, returning a new exponential.
                       */
                      function mulExp(uint a, uint b) pure internal returns (MathError, Exp memory) {
                          return mulExp(Exp({mantissa: a}), Exp({mantissa: b}));
                      }
                  
                      /**
                       * @dev Multiplies three exponentials, returning a new exponential.
                       */
                      function mulExp3(Exp memory a, Exp memory b, Exp memory c) pure internal returns (MathError, Exp memory) {
                          (MathError err, Exp memory ab) = mulExp(a, b);
                          if (err != MathError.NO_ERROR) {
                              return (err, ab);
                          }
                          return mulExp(ab, c);
                      }
                  
                      /**
                       * @dev Divides two exponentials, returning a new exponential.
                       *     (a/scale) / (b/scale) = (a/scale) * (scale/b) = a/b,
                       *  which we can scale as an Exp by calling getExp(a.mantissa, b.mantissa)
                       */
                      function divExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
                          return getExp(a.mantissa, b.mantissa);
                      }
                  
                      /**
                       * @dev Truncates the given exp to a whole number value.
                       *      For example, truncate(Exp{mantissa: 15 * expScale}) = 15
                       */
                      function truncate(Exp memory exp) pure internal returns (uint) {
                          // Note: We are not using careful math here as we're performing a division that cannot fail
                          return exp.mantissa / expScale;
                      }
                  
                      /**
                       * @dev Checks if first Exp is less than second Exp.
                       */
                      function lessThanExp(Exp memory left, Exp memory right) pure internal returns (bool) {
                          return left.mantissa < right.mantissa; //TODO: Add some simple tests and this in another PR yo.
                      }
                  
                      /**
                       * @dev Checks if left Exp <= right Exp.
                       */
                      function lessThanOrEqualExp(Exp memory left, Exp memory right) pure internal returns (bool) {
                          return left.mantissa <= right.mantissa;
                      }
                  
                      /**
                       * @dev returns true if Exp is exactly zero
                       */
                      function isZeroExp(Exp memory value) pure internal returns (bool) {
                          return value.mantissa == 0;
                      }
                  }
                  
                  // File: contracts/EIP20Interface.sol
                  
                  pragma solidity ^0.5.8;
                  
                  /**
                   * @title ERC 20 Token Standard Interface
                   *  https://eips.ethereum.org/EIPS/eip-20
                   */
                  interface EIP20Interface {
                  
                      /**
                        * @notice Get the total number of tokens in circulation
                        * @return The supply of tokens
                        */
                      function totalSupply() external view returns (uint256);
                  
                      /**
                       * @notice Gets the balance of the specified address
                       * @param owner The address from which the balance will be retrieved
                       * @return The balance
                       */
                      function balanceOf(address owner) external view returns (uint256 balance);
                  
                      /**
                        * @notice Transfer `amount` tokens from `msg.sender` to `dst`
                        * @param dst The address of the destination account
                        * @param amount The number of tokens to transfer
                        * @return Whether or not the transfer succeeded
                        */
                      function transfer(address dst, uint256 amount) external returns (bool success);
                  
                      /**
                        * @notice Transfer `amount` tokens from `src` to `dst`
                        * @param src The address of the source account
                        * @param dst The address of the destination account
                        * @param amount The number of tokens to transfer
                        * @return Whether or not the transfer succeeded
                        */
                      function transferFrom(address src, address dst, uint256 amount) external returns (bool success);
                  
                      /**
                        * @notice Approve `spender` to transfer up to `amount` from `src`
                        * @dev This will overwrite the approval amount for `spender`
                        *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
                        * @param spender The address of the account which may transfer tokens
                        * @param amount The number of tokens that are approved (-1 means infinite)
                        * @return Whether or not the approval succeeded
                        */
                      function approve(address spender, uint256 amount) external returns (bool success);
                  
                      /**
                        * @notice Get the current allowance from `owner` for `spender`
                        * @param owner The address of the account which owns the tokens to be spent
                        * @param spender The address of the account which may transfer tokens
                        * @return The number of tokens allowed to be spent (-1 means infinite)
                        */
                      function allowance(address owner, address spender) external view returns (uint256 remaining);
                  
                      event Transfer(address indexed from, address indexed to, uint256 amount);
                      event Approval(address indexed owner, address indexed spender, uint256 amount);
                  }
                  
                  // File: contracts/EIP20NonStandardInterface.sol
                  
                  pragma solidity ^0.5.8;
                  
                  /**
                   * @title EIP20NonStandardInterface
                   * @dev Version of ERC20 with no return values for `transfer` and `transferFrom`
                   *  See https://medium.com/coinmonks/missing-return-value-bug-at-least-130-tokens-affected-d67bf08521ca
                   */
                  interface EIP20NonStandardInterface {
                  
                      /**
                       * @notice Get the total number of tokens in circulation
                       * @return The supply of tokens
                       */
                      function totalSupply() external view returns (uint256);
                  
                      /**
                       * @notice Gets the balance of the specified address
                       * @param owner The address from which the balance will be retrieved
                       * @return The balance
                       */
                      function balanceOf(address owner) external view returns (uint256 balance);
                  
                      ///
                      /// !!!!!!!!!!!!!!
                      /// !!! NOTICE !!! `transfer` does not return a value, in violation of the ERC-20 specification
                      /// !!!!!!!!!!!!!!
                      ///
                  
                      /**
                        * @notice Transfer `amount` tokens from `msg.sender` to `dst`
                        * @param dst The address of the destination account
                        * @param amount The number of tokens to transfer
                        */
                      function transfer(address dst, uint256 amount) external;
                  
                      ///
                      /// !!!!!!!!!!!!!!
                      /// !!! NOTICE !!! `transferFrom` does not return a value, in violation of the ERC-20 specification
                      /// !!!!!!!!!!!!!!
                      ///
                  
                      /**
                        * @notice Transfer `amount` tokens from `src` to `dst`
                        * @param src The address of the source account
                        * @param dst The address of the destination account
                        * @param amount The number of tokens to transfer
                        */
                      function transferFrom(address src, address dst, uint256 amount) external;
                  
                      /**
                        * @notice Approve `spender` to transfer up to `amount` from `src`
                        * @dev This will overwrite the approval amount for `spender`
                        *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
                        * @param spender The address of the account which may transfer tokens
                        * @param amount The number of tokens that are approved
                        * @return Whether or not the approval succeeded
                        */
                      function approve(address spender, uint256 amount) external returns (bool success);
                  
                      /**
                        * @notice Get the current allowance from `owner` for `spender`
                        * @param owner The address of the account which owns the tokens to be spent
                        * @param spender The address of the account which may transfer tokens
                        * @return The number of tokens allowed to be spent
                        */
                      function allowance(address owner, address spender) external view returns (uint256 remaining);
                  
                      event Transfer(address indexed from, address indexed to, uint256 amount);
                      event Approval(address indexed owner, address indexed spender, uint256 amount);
                  }
                  
                  // File: contracts/ReentrancyGuard.sol
                  
                  pragma solidity ^0.5.8;
                  
                  /**
                   * @title Helps contracts guard against reentrancy attacks.
                   * @author Remco Bloemen <remco@2π.com>, Eenae <[email protected]>
                   * @dev If you mark a function `nonReentrant`, you should also
                   * mark it `external`.
                   */
                  contract ReentrancyGuard {
                      /// @dev counter to allow mutex lock with only one SSTORE operation
                      uint256 private _guardCounter;
                  
                      constructor () internal {
                          // The counter starts at one to prevent changing it from zero to a non-zero
                          // value, which is a more expensive operation.
                          _guardCounter = 1;
                      }
                  
                      /**
                       * @dev Prevents a contract from calling itself, directly or indirectly.
                       * Calling a `nonReentrant` function from another `nonReentrant`
                       * function is not supported. It is possible to prevent this from happening
                       * by making the `nonReentrant` function external, and make it call a
                       * `private` function that does the actual work.
                       */
                      modifier nonReentrant() {
                          _guardCounter += 1;
                          uint256 localCounter = _guardCounter;
                          _;
                          require(localCounter == _guardCounter, "re-entered");
                      }
                  }
                  
                  // File: contracts/InterestRateModel.sol
                  
                  pragma solidity ^0.5.8;
                  
                  /**
                    * @title The Compound InterestRateModel Interface
                    * @author Compound
                    * @notice Any interest rate model should derive from this contract.
                    * @dev These functions are specifically not marked `pure` as implementations of this
                    *      contract may read from storage variables.
                    */
                  interface InterestRateModel {
                      /**
                        * @notice Gets the current borrow interest rate based on the given asset, total cash, total borrows
                        *         and total reserves.
                        * @dev The return value should be scaled by 1e18, thus a return value of
                        *      `(true, 1000000000000)` implies an interest rate of 0.000001 or 0.0001% *per block*.
                        * @param cash The total cash of the underlying asset in the CToken
                        * @param borrows The total borrows of the underlying asset in the CToken
                        * @param reserves The total reserves of the underlying asset in the CToken
                        * @return Success or failure and the borrow interest rate per block scaled by 10e18
                        */
                      function getBorrowRate(uint cash, uint borrows, uint reserves) external view returns (uint, uint);
                  
                      /**
                        * @notice Marker function used for light validation when updating the interest rate model of a market
                        * @dev Marker function used for light validation when updating the interest rate model of a market. Implementations should simply return true.
                        * @return Success or failure
                        */
                      function isInterestRateModel() external view returns (bool);
                  }
                  
                  // File: contracts/CToken.sol
                  
                  pragma solidity ^0.5.8;
                  
                  
                  
                  
                  
                  
                  
                  
                  /**
                   * @title Compound's CToken Contract
                   * @notice Abstract base for CTokens
                   * @author Compound
                   */
                  contract CToken is EIP20Interface, Exponential, TokenErrorReporter, ReentrancyGuard {
                      /**
                       * @notice Indicator that this is a CToken contract (for inspection)
                       */
                      bool public constant isCToken = true;
                  
                      /**
                       * @notice EIP-20 token name for this token
                       */
                      string public name;
                  
                      /**
                       * @notice EIP-20 token symbol for this token
                       */
                      string public symbol;
                  
                      /**
                       * @notice EIP-20 token decimals for this token
                       */
                      uint public decimals;
                  
                      /**
                       * @notice Maximum borrow rate that can ever be applied (.0005% / block)
                       */
                      uint constant borrowRateMaxMantissa = 5e14;
                  
                      /**
                       * @notice Maximum fraction of interest that can be set aside for reserves
                       */
                      uint constant reserveFactorMaxMantissa = 1e18;
                  
                      /**
                       * @notice Administrator for this contract
                       */
                      address payable public admin;
                  
                      /**
                       * @notice Pending administrator for this contract
                       */
                      address payable public pendingAdmin;
                  
                      /**
                       * @notice Contract which oversees inter-cToken operations
                       */
                      ComptrollerInterface public comptroller;
                  
                      /**
                       * @notice Model which tells what the current interest rate should be
                       */
                      InterestRateModel public interestRateModel;
                  
                      /**
                       * @notice Initial exchange rate used when minting the first CTokens (used when totalSupply = 0)
                       */
                      uint public initialExchangeRateMantissa;
                  
                      /**
                       * @notice Fraction of interest currently set aside for reserves
                       */
                      uint public reserveFactorMantissa;
                  
                      /**
                       * @notice Block number that interest was last accrued at
                       */
                      uint public accrualBlockNumber;
                  
                      /**
                       * @notice Accumulator of total earned interest since the opening of the market
                       */
                      uint public borrowIndex;
                  
                      /**
                       * @notice Total amount of outstanding borrows of the underlying in this market
                       */
                      uint public totalBorrows;
                  
                      /**
                       * @notice Total amount of reserves of the underlying held in this market
                       */
                      uint public totalReserves;
                  
                      /**
                       * @notice Total number of tokens in circulation
                       */
                      uint256 public totalSupply;
                  
                      /**
                       * @notice Official record of token balances for each account
                       */
                      mapping (address => uint256) accountTokens;
                  
                      /**
                       * @notice Approved token transfer amounts on behalf of others
                       */
                      mapping (address => mapping (address => uint256)) transferAllowances;
                  
                      /**
                       * @notice Container for borrow balance information
                       * @member principal Total balance (with accrued interest), after applying the most recent balance-changing action
                       * @member interestIndex Global borrowIndex as of the most recent balance-changing action
                       */
                      struct BorrowSnapshot {
                          uint principal;
                          uint interestIndex;
                      }
                  
                      /**
                       * @notice Mapping of account addresses to outstanding borrow balances
                       */
                      mapping(address => BorrowSnapshot) accountBorrows;
                  
                  
                      /*** Market Events ***/
                  
                      /**
                       * @notice Event emitted when interest is accrued
                       */
                      event AccrueInterest(uint interestAccumulated, uint borrowIndex, uint totalBorrows);
                  
                      /**
                       * @notice Event emitted when tokens are minted
                       */
                      event Mint(address minter, uint mintAmount, uint mintTokens);
                  
                      /**
                       * @notice Event emitted when tokens are redeemed
                       */
                      event Redeem(address redeemer, uint redeemAmount, uint redeemTokens);
                  
                      /**
                       * @notice Event emitted when underlying is borrowed
                       */
                      event Borrow(address borrower, uint borrowAmount, uint accountBorrows, uint totalBorrows);
                  
                      /**
                       * @notice Event emitted when a borrow is repaid
                       */
                      event RepayBorrow(address payer, address borrower, uint repayAmount, uint accountBorrows, uint totalBorrows);
                  
                      /**
                       * @notice Event emitted when a borrow is liquidated
                       */
                      event LiquidateBorrow(address liquidator, address borrower, uint repayAmount, address cTokenCollateral, uint seizeTokens);
                  
                  
                      /*** Admin Events ***/
                  
                      /**
                       * @notice Event emitted when pendingAdmin is changed
                       */
                      event NewPendingAdmin(address oldPendingAdmin, address newPendingAdmin);
                  
                      /**
                       * @notice Event emitted when pendingAdmin is accepted, which means admin is updated
                       */
                      event NewAdmin(address oldAdmin, address newAdmin);
                  
                      /**
                       * @notice Event emitted when comptroller is changed
                       */
                      event NewComptroller(ComptrollerInterface oldComptroller, ComptrollerInterface newComptroller);
                  
                      /**
                       * @notice Event emitted when interestRateModel is changed
                       */
                      event NewMarketInterestRateModel(InterestRateModel oldInterestRateModel, InterestRateModel newInterestRateModel);
                  
                      /**
                       * @notice Event emitted when the reserve factor is changed
                       */
                      event NewReserveFactor(uint oldReserveFactorMantissa, uint newReserveFactorMantissa);
                  
                      /**
                       * @notice Event emitted when the reserves are reduced
                       */
                      event ReservesReduced(address admin, uint reduceAmount, uint newTotalReserves);
                  
                  
                      /**
                       * @notice Construct a new money market
                       * @param comptroller_ The address of the Comptroller
                       * @param interestRateModel_ The address of the interest rate model
                       * @param initialExchangeRateMantissa_ The initial exchange rate, scaled by 1e18
                       * @param name_ EIP-20 name of this token
                       * @param symbol_ EIP-20 symbol of this token
                       * @param decimals_ EIP-20 decimal precision of this token
                       */
                      constructor(ComptrollerInterface comptroller_,
                                  InterestRateModel interestRateModel_,
                                  uint initialExchangeRateMantissa_,
                                  string memory name_,
                                  string memory symbol_,
                                  uint decimals_) internal {
                          // Set admin to msg.sender
                          admin = msg.sender;
                  
                          // Set initial exchange rate
                          initialExchangeRateMantissa = initialExchangeRateMantissa_;
                          require(initialExchangeRateMantissa > 0, "Initial exchange rate must be greater than zero.");
                  
                          // Set the comptroller
                          uint err = _setComptroller(comptroller_);
                          require(err == uint(Error.NO_ERROR), "Setting comptroller failed");
                  
                          // Initialize block number and borrow index (block number mocks depend on comptroller being set)
                          accrualBlockNumber = getBlockNumber();
                          borrowIndex = mantissaOne;
                  
                          // Set the interest rate model (depends on block number / borrow index)
                          err = _setInterestRateModelFresh(interestRateModel_);
                          require(err == uint(Error.NO_ERROR), "Setting interest rate model failed");
                  
                          name = name_;
                          symbol = symbol_;
                          decimals = decimals_;
                      }
                  
                      /**
                       * @notice Transfer `tokens` tokens from `src` to `dst` by `spender`
                       * @dev Called by both `transfer` and `transferFrom` internally
                       * @param spender The address of the account performing the transfer
                       * @param src The address of the source account
                       * @param dst The address of the destination account
                       * @param tokens The number of tokens to transfer
                       * @return Whether or not the transfer succeeded
                       */
                      function transferTokens(address spender, address src, address dst, uint tokens) internal returns (uint) {
                          /* Fail if transfer not allowed */
                          uint allowed = comptroller.transferAllowed(address(this), src, dst, tokens);
                          if (allowed != 0) {
                              return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.TRANSFER_COMPTROLLER_REJECTION, allowed);
                          }
                  
                          /* Do not allow self-transfers */
                          if (src == dst) {
                              return fail(Error.BAD_INPUT, FailureInfo.TRANSFER_NOT_ALLOWED);
                          }
                  
                          /* Get the allowance, infinite for the account owner */
                          uint startingAllowance = 0;
                          if (spender == src) {
                              startingAllowance = uint(-1);
                          } else {
                              startingAllowance = transferAllowances[src][spender];
                          }
                  
                          /* Do the calculations, checking for {under,over}flow */
                          MathError mathErr;
                          uint allowanceNew;
                          uint srcTokensNew;
                          uint dstTokensNew;
                  
                          (mathErr, allowanceNew) = subUInt(startingAllowance, tokens);
                          if (mathErr != MathError.NO_ERROR) {
                              return fail(Error.MATH_ERROR, FailureInfo.TRANSFER_NOT_ALLOWED);
                          }
                  
                          (mathErr, srcTokensNew) = subUInt(accountTokens[src], tokens);
                          if (mathErr != MathError.NO_ERROR) {
                              return fail(Error.MATH_ERROR, FailureInfo.TRANSFER_NOT_ENOUGH);
                          }
                  
                          (mathErr, dstTokensNew) = addUInt(accountTokens[dst], tokens);
                          if (mathErr != MathError.NO_ERROR) {
                              return fail(Error.MATH_ERROR, FailureInfo.TRANSFER_TOO_MUCH);
                          }
                  
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                  
                          accountTokens[src] = srcTokensNew;
                          accountTokens[dst] = dstTokensNew;
                  
                          /* Eat some of the allowance (if necessary) */
                          if (startingAllowance != uint(-1)) {
                              transferAllowances[src][spender] = allowanceNew;
                          }
                  
                          /* We emit a Transfer event */
                          emit Transfer(src, dst, tokens);
                  
                          /* We call the defense hook (which checks for under-collateralization) */
                          comptroller.transferVerify(address(this), src, dst, tokens);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice Transfer `amount` tokens from `msg.sender` to `dst`
                       * @param dst The address of the destination account
                       * @param amount The number of tokens to transfer
                       * @return Whether or not the transfer succeeded
                       */
                      function transfer(address dst, uint256 amount) external nonReentrant returns (bool) {
                          return transferTokens(msg.sender, msg.sender, dst, amount) == uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice Transfer `amount` tokens from `src` to `dst`
                       * @param src The address of the source account
                       * @param dst The address of the destination account
                       * @param amount The number of tokens to transfer
                       * @return Whether or not the transfer succeeded
                       */
                      function transferFrom(address src, address dst, uint256 amount) external nonReentrant returns (bool) {
                          return transferTokens(msg.sender, src, dst, amount) == uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice Approve `spender` to transfer up to `amount` from `src`
                       * @dev This will overwrite the approval amount for `spender`
                       *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
                       * @param spender The address of the account which may transfer tokens
                       * @param amount The number of tokens that are approved (-1 means infinite)
                       * @return Whether or not the approval succeeded
                       */
                      function approve(address spender, uint256 amount) external returns (bool) {
                          address src = msg.sender;
                          transferAllowances[src][spender] = amount;
                          emit Approval(src, spender, amount);
                          return true;
                      }
                  
                      /**
                       * @notice Get the current allowance from `owner` for `spender`
                       * @param owner The address of the account which owns the tokens to be spent
                       * @param spender The address of the account which may transfer tokens
                       * @return The number of tokens allowed to be spent (-1 means infinite)
                       */
                      function allowance(address owner, address spender) external view returns (uint256) {
                          return transferAllowances[owner][spender];
                      }
                  
                      /**
                       * @notice Get the token balance of the `owner`
                       * @param owner The address of the account to query
                       * @return The number of tokens owned by `owner`
                       */
                      function balanceOf(address owner) external view returns (uint256) {
                          return accountTokens[owner];
                      }
                  
                      /**
                       * @notice Get the underlying balance of the `owner`
                       * @dev This also accrues interest in a transaction
                       * @param owner The address of the account to query
                       * @return The amount of underlying owned by `owner`
                       */
                      function balanceOfUnderlying(address owner) external returns (uint) {
                          Exp memory exchangeRate = Exp({mantissa: exchangeRateCurrent()});
                          (MathError mErr, uint balance) = mulScalarTruncate(exchangeRate, accountTokens[owner]);
                          require(mErr == MathError.NO_ERROR);
                          return balance;
                      }
                  
                      /**
                       * @notice Get a snapshot of the account's balances, and the cached exchange rate
                       * @dev This is used by comptroller to more efficiently perform liquidity checks.
                       * @param account Address of the account to snapshot
                       * @return (possible error, token balance, borrow balance, exchange rate mantissa)
                       */
                      function getAccountSnapshot(address account) external view returns (uint, uint, uint, uint) {
                          uint cTokenBalance = accountTokens[account];
                          uint borrowBalance;
                          uint exchangeRateMantissa;
                  
                          MathError mErr;
                  
                          (mErr, borrowBalance) = borrowBalanceStoredInternal(account);
                          if (mErr != MathError.NO_ERROR) {
                              return (uint(Error.MATH_ERROR), 0, 0, 0);
                          }
                  
                          (mErr, exchangeRateMantissa) = exchangeRateStoredInternal();
                          if (mErr != MathError.NO_ERROR) {
                              return (uint(Error.MATH_ERROR), 0, 0, 0);
                          }
                  
                          return (uint(Error.NO_ERROR), cTokenBalance, borrowBalance, exchangeRateMantissa);
                      }
                  
                      /**
                       * @dev Function to simply retrieve block number
                       *  This exists mainly for inheriting test contracts to stub this result.
                       */
                      function getBlockNumber() internal view returns (uint) {
                          return block.number;
                      }
                  
                      /**
                       * @notice Returns the current per-block borrow interest rate for this cToken
                       * @return The borrow interest rate per block, scaled by 1e18
                       */
                      function borrowRatePerBlock() external view returns (uint) {
                          (uint opaqueErr, uint borrowRateMantissa) = interestRateModel.getBorrowRate(getCashPrior(), totalBorrows, totalReserves);
                          require(opaqueErr == 0, "borrowRatePerBlock: interestRateModel.borrowRate failed"); // semi-opaque
                          return borrowRateMantissa;
                      }
                  
                      /**
                       * @notice Returns the current per-block supply interest rate for this cToken
                       * @return The supply interest rate per block, scaled by 1e18
                       */
                      function supplyRatePerBlock() external view returns (uint) {
                          /* We calculate the supply rate:
                           *  underlying = totalSupply × exchangeRate
                           *  borrowsPer = totalBorrows ÷ underlying
                           *  supplyRate = borrowRate × (1-reserveFactor) × borrowsPer
                           */
                          uint exchangeRateMantissa = exchangeRateStored();
                  
                          (uint e0, uint borrowRateMantissa) = interestRateModel.getBorrowRate(getCashPrior(), totalBorrows, totalReserves);
                          require(e0 == 0, "supplyRatePerBlock: calculating borrowRate failed"); // semi-opaque
                  
                          (MathError e1, Exp memory underlying) = mulScalar(Exp({mantissa: exchangeRateMantissa}), totalSupply);
                          require(e1 == MathError.NO_ERROR, "supplyRatePerBlock: calculating underlying failed");
                  
                          (MathError e2, Exp memory borrowsPer) = divScalarByExp(totalBorrows, underlying);
                          require(e2 == MathError.NO_ERROR, "supplyRatePerBlock: calculating borrowsPer failed");
                  
                          (MathError e3, Exp memory oneMinusReserveFactor) = subExp(Exp({mantissa: mantissaOne}), Exp({mantissa: reserveFactorMantissa}));
                          require(e3 == MathError.NO_ERROR, "supplyRatePerBlock: calculating oneMinusReserveFactor failed");
                  
                          (MathError e4, Exp memory supplyRate) = mulExp3(Exp({mantissa: borrowRateMantissa}), oneMinusReserveFactor, borrowsPer);
                          require(e4 == MathError.NO_ERROR, "supplyRatePerBlock: calculating supplyRate failed");
                  
                          return supplyRate.mantissa;
                      }
                  
                      /**
                       * @notice Returns the current total borrows plus accrued interest
                       * @return The total borrows with interest
                       */
                      function totalBorrowsCurrent() external nonReentrant returns (uint) {
                          require(accrueInterest() == uint(Error.NO_ERROR), "accrue interest failed");
                          return totalBorrows;
                      }
                  
                      /**
                       * @notice Accrue interest to updated borrowIndex and then calculate account's borrow balance using the updated borrowIndex
                       * @param account The address whose balance should be calculated after updating borrowIndex
                       * @return The calculated balance
                       */
                      function borrowBalanceCurrent(address account) external nonReentrant returns (uint) {
                          require(accrueInterest() == uint(Error.NO_ERROR), "accrue interest failed");
                          return borrowBalanceStored(account);
                      }
                  
                      /**
                       * @notice Return the borrow balance of account based on stored data
                       * @param account The address whose balance should be calculated
                       * @return The calculated balance
                       */
                      function borrowBalanceStored(address account) public view returns (uint) {
                          (MathError err, uint result) = borrowBalanceStoredInternal(account);
                          require(err == MathError.NO_ERROR, "borrowBalanceStored: borrowBalanceStoredInternal failed");
                          return result;
                      }
                  
                      /**
                       * @notice Return the borrow balance of account based on stored data
                       * @param account The address whose balance should be calculated
                       * @return (error code, the calculated balance or 0 if error code is non-zero)
                       */
                      function borrowBalanceStoredInternal(address account) internal view returns (MathError, uint) {
                          /* Note: we do not assert that the market is up to date */
                          MathError mathErr;
                          uint principalTimesIndex;
                          uint result;
                  
                          /* Get borrowBalance and borrowIndex */
                          BorrowSnapshot storage borrowSnapshot = accountBorrows[account];
                  
                          /* If borrowBalance = 0 then borrowIndex is likely also 0.
                           * Rather than failing the calculation with a division by 0, we immediately return 0 in this case.
                           */
                          if (borrowSnapshot.principal == 0) {
                              return (MathError.NO_ERROR, 0);
                          }
                  
                          /* Calculate new borrow balance using the interest index:
                           *  recentBorrowBalance = borrower.borrowBalance * market.borrowIndex / borrower.borrowIndex
                           */
                          (mathErr, principalTimesIndex) = mulUInt(borrowSnapshot.principal, borrowIndex);
                          if (mathErr != MathError.NO_ERROR) {
                              return (mathErr, 0);
                          }
                  
                          (mathErr, result) = divUInt(principalTimesIndex, borrowSnapshot.interestIndex);
                          if (mathErr != MathError.NO_ERROR) {
                              return (mathErr, 0);
                          }
                  
                          return (MathError.NO_ERROR, result);
                      }
                  
                      /**
                       * @notice Accrue interest then return the up-to-date exchange rate
                       * @return Calculated exchange rate scaled by 1e18
                       */
                      function exchangeRateCurrent() public nonReentrant returns (uint) {
                          require(accrueInterest() == uint(Error.NO_ERROR), "accrue interest failed");
                          return exchangeRateStored();
                      }
                  
                      /**
                       * @notice Calculates the exchange rate from the underlying to the CToken
                       * @dev This function does not accrue interest before calculating the exchange rate
                       * @return Calculated exchange rate scaled by 1e18
                       */
                      function exchangeRateStored() public view returns (uint) {
                          (MathError err, uint result) = exchangeRateStoredInternal();
                          require(err == MathError.NO_ERROR, "exchangeRateStored: exchangeRateStoredInternal failed");
                          return result;
                      }
                  
                      /**
                       * @notice Calculates the exchange rate from the underlying to the CToken
                       * @dev This function does not accrue interest before calculating the exchange rate
                       * @return (error code, calculated exchange rate scaled by 1e18)
                       */
                      function exchangeRateStoredInternal() internal view returns (MathError, uint) {
                          if (totalSupply == 0) {
                              /*
                               * If there are no tokens minted:
                               *  exchangeRate = initialExchangeRate
                               */
                              return (MathError.NO_ERROR, initialExchangeRateMantissa);
                          } else {
                              /*
                               * Otherwise:
                               *  exchangeRate = (totalCash + totalBorrows - totalReserves) / totalSupply
                               */
                              uint totalCash = getCashPrior();
                              uint cashPlusBorrowsMinusReserves;
                              Exp memory exchangeRate;
                              MathError mathErr;
                  
                              (mathErr, cashPlusBorrowsMinusReserves) = addThenSubUInt(totalCash, totalBorrows, totalReserves);
                              if (mathErr != MathError.NO_ERROR) {
                                  return (mathErr, 0);
                              }
                  
                              (mathErr, exchangeRate) = getExp(cashPlusBorrowsMinusReserves, totalSupply);
                              if (mathErr != MathError.NO_ERROR) {
                                  return (mathErr, 0);
                              }
                  
                              return (MathError.NO_ERROR, exchangeRate.mantissa);
                          }
                      }
                  
                      /**
                       * @notice Get cash balance of this cToken in the underlying asset
                       * @return The quantity of underlying asset owned by this contract
                       */
                      function getCash() external view returns (uint) {
                          return getCashPrior();
                      }
                  
                      struct AccrueInterestLocalVars {
                          MathError mathErr;
                          uint opaqueErr;
                          uint borrowRateMantissa;
                          uint currentBlockNumber;
                          uint blockDelta;
                  
                          Exp simpleInterestFactor;
                  
                          uint interestAccumulated;
                          uint totalBorrowsNew;
                          uint totalReservesNew;
                          uint borrowIndexNew;
                      }
                  
                      /**
                        * @notice Applies accrued interest to total borrows and reserves.
                        * @dev This calculates interest accrued from the last checkpointed block
                        *      up to the current block and writes new checkpoint to storage.
                        */
                      function accrueInterest() public returns (uint) {
                          AccrueInterestLocalVars memory vars;
                  
                          /* Calculate the current borrow interest rate */
                          (vars.opaqueErr, vars.borrowRateMantissa) = interestRateModel.getBorrowRate(getCashPrior(), totalBorrows, totalReserves);
                          require(vars.borrowRateMantissa <= borrowRateMaxMantissa, "borrow rate is absurdly high");
                          if (vars.opaqueErr != 0) {
                              return failOpaque(Error.INTEREST_RATE_MODEL_ERROR, FailureInfo.ACCRUE_INTEREST_BORROW_RATE_CALCULATION_FAILED, vars.opaqueErr);
                          }
                  
                          /* Remember the initial block number */
                          vars.currentBlockNumber = getBlockNumber();
                  
                          /* Calculate the number of blocks elapsed since the last accrual */
                          (vars.mathErr, vars.blockDelta) = subUInt(vars.currentBlockNumber, accrualBlockNumber);
                          assert(vars.mathErr == MathError.NO_ERROR); // Block delta should always succeed and if it doesn't, blow up.
                  
                          /*
                           * Calculate the interest accumulated into borrows and reserves and the new index:
                           *  simpleInterestFactor = borrowRate * blockDelta
                           *  interestAccumulated = simpleInterestFactor * totalBorrows
                           *  totalBorrowsNew = interestAccumulated + totalBorrows
                           *  totalReservesNew = interestAccumulated * reserveFactor + totalReserves
                           *  borrowIndexNew = simpleInterestFactor * borrowIndex + borrowIndex
                           */
                          (vars.mathErr, vars.simpleInterestFactor) = mulScalar(Exp({mantissa: vars.borrowRateMantissa}), vars.blockDelta);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_SIMPLE_INTEREST_FACTOR_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.interestAccumulated) = mulScalarTruncate(vars.simpleInterestFactor, totalBorrows);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_ACCUMULATED_INTEREST_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.totalBorrowsNew) = addUInt(vars.interestAccumulated, totalBorrows);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_NEW_TOTAL_BORROWS_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.totalReservesNew) = mulScalarTruncateAddUInt(Exp({mantissa: reserveFactorMantissa}), vars.interestAccumulated, totalReserves);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_NEW_TOTAL_RESERVES_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.borrowIndexNew) = mulScalarTruncateAddUInt(vars.simpleInterestFactor, borrowIndex, borrowIndex);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_NEW_BORROW_INDEX_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                  
                          /* We write the previously calculated values into storage */
                          accrualBlockNumber = vars.currentBlockNumber;
                          borrowIndex = vars.borrowIndexNew;
                          totalBorrows = vars.totalBorrowsNew;
                          totalReserves = vars.totalReservesNew;
                  
                          /* We emit an AccrueInterest event */
                          emit AccrueInterest(vars.interestAccumulated, vars.borrowIndexNew, totalBorrows);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice Sender supplies assets into the market and receives cTokens in exchange
                       * @dev Accrues interest whether or not the operation succeeds, unless reverted
                       * @param mintAmount The amount of the underlying asset to supply
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function mintInternal(uint mintAmount) internal nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
                              return fail(Error(error), FailureInfo.MINT_ACCRUE_INTEREST_FAILED);
                          }
                          // mintFresh emits the actual Mint event if successful and logs on errors, so we don't need to
                          return mintFresh(msg.sender, mintAmount);
                      }
                  
                      struct MintLocalVars {
                          Error err;
                          MathError mathErr;
                          uint exchangeRateMantissa;
                          uint mintTokens;
                          uint totalSupplyNew;
                          uint accountTokensNew;
                      }
                  
                      /**
                       * @notice User supplies assets into the market and receives cTokens in exchange
                       * @dev Assumes interest has already been accrued up to the current block
                       * @param minter The address of the account which is supplying the assets
                       * @param mintAmount The amount of the underlying asset to supply
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function mintFresh(address minter, uint mintAmount) internal returns (uint) {
                          /* Fail if mint not allowed */
                          uint allowed = comptroller.mintAllowed(address(this), minter, mintAmount);
                          if (allowed != 0) {
                              return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.MINT_COMPTROLLER_REJECTION, allowed);
                          }
                  
                          /* Verify market's block number equals current block number */
                          if (accrualBlockNumber != getBlockNumber()) {
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.MINT_FRESHNESS_CHECK);
                          }
                  
                          MintLocalVars memory vars;
                  
                          /* Fail if checkTransferIn fails */
                          vars.err = checkTransferIn(minter, mintAmount);
                          if (vars.err != Error.NO_ERROR) {
                              return fail(vars.err, FailureInfo.MINT_TRANSFER_IN_NOT_POSSIBLE);
                          }
                  
                          /*
                           * We get the current exchange rate and calculate the number of cTokens to be minted:
                           *  mintTokens = mintAmount / exchangeRate
                           */
                          (vars.mathErr, vars.exchangeRateMantissa) = exchangeRateStoredInternal();
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_EXCHANGE_RATE_READ_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.mintTokens) = divScalarByExpTruncate(mintAmount, Exp({mantissa: vars.exchangeRateMantissa}));
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_EXCHANGE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          /*
                           * We calculate the new total supply of cTokens and minter token balance, checking for overflow:
                           *  totalSupplyNew = totalSupply + mintTokens
                           *  accountTokensNew = accountTokens[minter] + mintTokens
                           */
                          (vars.mathErr, vars.totalSupplyNew) = addUInt(totalSupply, vars.mintTokens);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_NEW_TOTAL_SUPPLY_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.accountTokensNew) = addUInt(accountTokens[minter], vars.mintTokens);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.MINT_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                  
                          /*
                           * We call doTransferIn for the minter and the mintAmount
                           *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
                           *  On success, the cToken holds an additional mintAmount of cash.
                           *  If doTransferIn fails despite the fact we checked pre-conditions,
                           *   we revert because we can't be sure if side effects occurred.
                           */
                          vars.err = doTransferIn(minter, mintAmount);
                          if (vars.err != Error.NO_ERROR) {
                              return fail(vars.err, FailureInfo.MINT_TRANSFER_IN_FAILED);
                          }
                  
                          /* We write previously calculated values into storage */
                          totalSupply = vars.totalSupplyNew;
                          accountTokens[minter] = vars.accountTokensNew;
                  
                          /* We emit a Mint event, and a Transfer event */
                          emit Mint(minter, mintAmount, vars.mintTokens);
                          emit Transfer(address(this), minter, vars.mintTokens);
                  
                          /* We call the defense hook */
                          comptroller.mintVerify(address(this), minter, mintAmount, vars.mintTokens);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice Sender redeems cTokens in exchange for the underlying asset
                       * @dev Accrues interest whether or not the operation succeeds, unless reverted
                       * @param redeemTokens The number of cTokens to redeem into underlying
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function redeemInternal(uint redeemTokens) internal nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted redeem failed
                              return fail(Error(error), FailureInfo.REDEEM_ACCRUE_INTEREST_FAILED);
                          }
                          // redeemFresh emits redeem-specific logs on errors, so we don't need to
                          return redeemFresh(msg.sender, redeemTokens, 0);
                      }
                  
                      /**
                       * @notice Sender redeems cTokens in exchange for a specified amount of underlying asset
                       * @dev Accrues interest whether or not the operation succeeds, unless reverted
                       * @param redeemAmount The amount of underlying to redeem
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function redeemUnderlyingInternal(uint redeemAmount) internal nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted redeem failed
                              return fail(Error(error), FailureInfo.REDEEM_ACCRUE_INTEREST_FAILED);
                          }
                          // redeemFresh emits redeem-specific logs on errors, so we don't need to
                          return redeemFresh(msg.sender, 0, redeemAmount);
                      }
                  
                      struct RedeemLocalVars {
                          Error err;
                          MathError mathErr;
                          uint exchangeRateMantissa;
                          uint redeemTokens;
                          uint redeemAmount;
                          uint totalSupplyNew;
                          uint accountTokensNew;
                      }
                  
                      /**
                       * @notice User redeems cTokens in exchange for the underlying asset
                       * @dev Assumes interest has already been accrued up to the current block
                       * @param redeemer The address of the account which is redeeming the tokens
                       * @param redeemTokensIn The number of cTokens to redeem into underlying (only one of redeemTokensIn or redeemAmountIn may be zero)
                       * @param redeemAmountIn The number of cTokens to redeem into underlying (only one of redeemTokensIn or redeemAmountIn may be zero)
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function redeemFresh(address payable redeemer, uint redeemTokensIn, uint redeemAmountIn) internal returns (uint) {
                          require(redeemTokensIn == 0 || redeemAmountIn == 0, "one of redeemTokensIn or redeemAmountIn must be zero");
                  
                          RedeemLocalVars memory vars;
                  
                          /* exchangeRate = invoke Exchange Rate Stored() */
                          (vars.mathErr, vars.exchangeRateMantissa) = exchangeRateStoredInternal();
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_EXCHANGE_RATE_READ_FAILED, uint(vars.mathErr));
                          }
                  
                          /* If redeemTokensIn > 0: */
                          if (redeemTokensIn > 0) {
                              /*
                               * We calculate the exchange rate and the amount of underlying to be redeemed:
                               *  redeemTokens = redeemTokensIn
                               *  redeemAmount = redeemTokensIn x exchangeRateCurrent
                               */
                              vars.redeemTokens = redeemTokensIn;
                  
                              (vars.mathErr, vars.redeemAmount) = mulScalarTruncate(Exp({mantissa: vars.exchangeRateMantissa}), redeemTokensIn);
                              if (vars.mathErr != MathError.NO_ERROR) {
                                  return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_EXCHANGE_TOKENS_CALCULATION_FAILED, uint(vars.mathErr));
                              }
                          } else {
                              /*
                               * We get the current exchange rate and calculate the amount to be redeemed:
                               *  redeemTokens = redeemAmountIn / exchangeRate
                               *  redeemAmount = redeemAmountIn
                               */
                  
                              (vars.mathErr, vars.redeemTokens) = divScalarByExpTruncate(redeemAmountIn, Exp({mantissa: vars.exchangeRateMantissa}));
                              if (vars.mathErr != MathError.NO_ERROR) {
                                  return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_EXCHANGE_AMOUNT_CALCULATION_FAILED, uint(vars.mathErr));
                              }
                  
                              vars.redeemAmount = redeemAmountIn;
                          }
                  
                          /* Fail if redeem not allowed */
                          uint allowed = comptroller.redeemAllowed(address(this), redeemer, vars.redeemTokens);
                          if (allowed != 0) {
                              return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.REDEEM_COMPTROLLER_REJECTION, allowed);
                          }
                  
                          /* Verify market's block number equals current block number */
                          if (accrualBlockNumber != getBlockNumber()) {
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.REDEEM_FRESHNESS_CHECK);
                          }
                  
                          /*
                           * We calculate the new total supply and redeemer balance, checking for underflow:
                           *  totalSupplyNew = totalSupply - redeemTokens
                           *  accountTokensNew = accountTokens[redeemer] - redeemTokens
                           */
                          (vars.mathErr, vars.totalSupplyNew) = subUInt(totalSupply, vars.redeemTokens);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_NEW_TOTAL_SUPPLY_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.accountTokensNew) = subUInt(accountTokens[redeemer], vars.redeemTokens);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          /* Fail gracefully if protocol has insufficient cash */
                          if (getCashPrior() < vars.redeemAmount) {
                              return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.REDEEM_TRANSFER_OUT_NOT_POSSIBLE);
                          }
                  
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                  
                          /*
                           * We invoke doTransferOut for the redeemer and the redeemAmount.
                           *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
                           *  On success, the cToken has redeemAmount less of cash.
                           *  If doTransferOut fails despite the fact we checked pre-conditions,
                           *   we revert because we can't be sure if side effects occurred.
                           */
                          vars.err = doTransferOut(redeemer, vars.redeemAmount);
                          require(vars.err == Error.NO_ERROR, "redeem transfer out failed");
                  
                          /* We write previously calculated values into storage */
                          totalSupply = vars.totalSupplyNew;
                          accountTokens[redeemer] = vars.accountTokensNew;
                  
                          /* We emit a Transfer event, and a Redeem event */
                          emit Transfer(redeemer, address(this), vars.redeemTokens);
                          emit Redeem(redeemer, vars.redeemAmount, vars.redeemTokens);
                  
                          /* We call the defense hook */
                          comptroller.redeemVerify(address(this), redeemer, vars.redeemAmount, vars.redeemTokens);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                        * @notice Sender borrows assets from the protocol to their own address
                        * @param borrowAmount The amount of the underlying asset to borrow
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function borrowInternal(uint borrowAmount) internal nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
                              return fail(Error(error), FailureInfo.BORROW_ACCRUE_INTEREST_FAILED);
                          }
                          // borrowFresh emits borrow-specific logs on errors, so we don't need to
                          return borrowFresh(msg.sender, borrowAmount);
                      }
                  
                      struct BorrowLocalVars {
                          Error err;
                          MathError mathErr;
                          uint accountBorrows;
                          uint accountBorrowsNew;
                          uint totalBorrowsNew;
                      }
                  
                      /**
                        * @notice Users borrow assets from the protocol to their own address
                        * @param borrowAmount The amount of the underlying asset to borrow
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function borrowFresh(address payable borrower, uint borrowAmount) internal returns (uint) {
                          /* Fail if borrow not allowed */
                          uint allowed = comptroller.borrowAllowed(address(this), borrower, borrowAmount);
                          if (allowed != 0) {
                              return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.BORROW_COMPTROLLER_REJECTION, allowed);
                          }
                  
                          /* Verify market's block number equals current block number */
                          if (accrualBlockNumber != getBlockNumber()) {
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.BORROW_FRESHNESS_CHECK);
                          }
                  
                          /* Fail gracefully if protocol has insufficient underlying cash */
                          if (getCashPrior() < borrowAmount) {
                              return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.BORROW_CASH_NOT_AVAILABLE);
                          }
                  
                          BorrowLocalVars memory vars;
                  
                          /*
                           * We calculate the new borrower and total borrow balances, failing on overflow:
                           *  accountBorrowsNew = accountBorrows + borrowAmount
                           *  totalBorrowsNew = totalBorrows + borrowAmount
                           */
                          (vars.mathErr, vars.accountBorrows) = borrowBalanceStoredInternal(borrower);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.accountBorrowsNew) = addUInt(vars.accountBorrows, borrowAmount);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.totalBorrowsNew) = addUInt(totalBorrows, borrowAmount);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                  
                          /*
                           * We invoke doTransferOut for the borrower and the borrowAmount.
                           *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
                           *  On success, the cToken borrowAmount less of cash.
                           *  If doTransferOut fails despite the fact we checked pre-conditions,
                           *   we revert because we can't be sure if side effects occurred.
                           */
                          vars.err = doTransferOut(borrower, borrowAmount);
                          require(vars.err == Error.NO_ERROR, "borrow transfer out failed");
                  
                          /* We write the previously calculated values into storage */
                          accountBorrows[borrower].principal = vars.accountBorrowsNew;
                          accountBorrows[borrower].interestIndex = borrowIndex;
                          totalBorrows = vars.totalBorrowsNew;
                  
                          /* We emit a Borrow event */
                          emit Borrow(borrower, borrowAmount, vars.accountBorrowsNew, vars.totalBorrowsNew);
                  
                          /* We call the defense hook */
                          comptroller.borrowVerify(address(this), borrower, borrowAmount);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice Sender repays their own borrow
                       * @param repayAmount The amount to repay
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function repayBorrowInternal(uint repayAmount) internal nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
                              return fail(Error(error), FailureInfo.REPAY_BORROW_ACCRUE_INTEREST_FAILED);
                          }
                          // repayBorrowFresh emits repay-borrow-specific logs on errors, so we don't need to
                          return repayBorrowFresh(msg.sender, msg.sender, repayAmount);
                      }
                  
                      /**
                       * @notice Sender repays a borrow belonging to borrower
                       * @param borrower the account with the debt being payed off
                       * @param repayAmount The amount to repay
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function repayBorrowBehalfInternal(address borrower, uint repayAmount) internal nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
                              return fail(Error(error), FailureInfo.REPAY_BEHALF_ACCRUE_INTEREST_FAILED);
                          }
                          // repayBorrowFresh emits repay-borrow-specific logs on errors, so we don't need to
                          return repayBorrowFresh(msg.sender, borrower, repayAmount);
                      }
                  
                      struct RepayBorrowLocalVars {
                          Error err;
                          MathError mathErr;
                          uint repayAmount;
                          uint borrowerIndex;
                          uint accountBorrows;
                          uint accountBorrowsNew;
                          uint totalBorrowsNew;
                      }
                  
                      /**
                       * @notice Borrows are repaid by another user (possibly the borrower).
                       * @param payer the account paying off the borrow
                       * @param borrower the account with the debt being payed off
                       * @param repayAmount the amount of undelrying tokens being returned
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function repayBorrowFresh(address payer, address borrower, uint repayAmount) internal returns (uint) {
                          /* Fail if repayBorrow not allowed */
                          uint allowed = comptroller.repayBorrowAllowed(address(this), payer, borrower, repayAmount);
                          if (allowed != 0) {
                              return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.REPAY_BORROW_COMPTROLLER_REJECTION, allowed);
                          }
                  
                          /* Verify market's block number equals current block number */
                          if (accrualBlockNumber != getBlockNumber()) {
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.REPAY_BORROW_FRESHNESS_CHECK);
                          }
                  
                          RepayBorrowLocalVars memory vars;
                  
                          /* We remember the original borrowerIndex for verification purposes */
                          vars.borrowerIndex = accountBorrows[borrower].interestIndex;
                  
                          /* We fetch the amount the borrower owes, with accumulated interest */
                          (vars.mathErr, vars.accountBorrows) = borrowBalanceStoredInternal(borrower);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.REPAY_BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          /* If repayAmount == -1, repayAmount = accountBorrows */
                          if (repayAmount == uint(-1)) {
                              vars.repayAmount = vars.accountBorrows;
                          } else {
                              vars.repayAmount = repayAmount;
                          }
                  
                          /* Fail if checkTransferIn fails */
                          vars.err = checkTransferIn(payer, vars.repayAmount);
                          if (vars.err != Error.NO_ERROR) {
                              return fail(vars.err, FailureInfo.REPAY_BORROW_TRANSFER_IN_NOT_POSSIBLE);
                          }
                  
                          /*
                           * We calculate the new borrower and total borrow balances, failing on underflow:
                           *  accountBorrowsNew = accountBorrows - repayAmount
                           *  totalBorrowsNew = totalBorrows - repayAmount
                           */
                          (vars.mathErr, vars.accountBorrowsNew) = subUInt(vars.accountBorrows, vars.repayAmount);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.REPAY_BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          (vars.mathErr, vars.totalBorrowsNew) = subUInt(totalBorrows, vars.repayAmount);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.REPAY_BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                  
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                  
                          /*
                           * We call doTransferIn for the payer and the repayAmount
                           *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
                           *  On success, the cToken holds an additional repayAmount of cash.
                           *  If doTransferIn fails despite the fact we checked pre-conditions,
                           *   we revert because we can't be sure if side effects occurred.
                           */
                          vars.err = doTransferIn(payer, vars.repayAmount);
                          require(vars.err == Error.NO_ERROR, "repay borrow transfer in failed");
                  
                          /* We write the previously calculated values into storage */
                          accountBorrows[borrower].principal = vars.accountBorrowsNew;
                          accountBorrows[borrower].interestIndex = borrowIndex;
                          totalBorrows = vars.totalBorrowsNew;
                  
                          /* We emit a RepayBorrow event */
                          emit RepayBorrow(payer, borrower, vars.repayAmount, vars.accountBorrowsNew, vars.totalBorrowsNew);
                  
                          /* We call the defense hook */
                          comptroller.repayBorrowVerify(address(this), payer, borrower, vars.repayAmount, vars.borrowerIndex);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice The sender liquidates the borrowers collateral.
                       *  The collateral seized is transferred to the liquidator.
                       * @param borrower The borrower of this cToken to be liquidated
                       * @param cTokenCollateral The market in which to seize collateral from the borrower
                       * @param repayAmount The amount of the underlying borrowed asset to repay
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function liquidateBorrowInternal(address borrower, uint repayAmount, CToken cTokenCollateral) internal nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted liquidation failed
                              return fail(Error(error), FailureInfo.LIQUIDATE_ACCRUE_BORROW_INTEREST_FAILED);
                          }
                  
                          error = cTokenCollateral.accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted liquidation failed
                              return fail(Error(error), FailureInfo.LIQUIDATE_ACCRUE_COLLATERAL_INTEREST_FAILED);
                          }
                  
                          // liquidateBorrowFresh emits borrow-specific logs on errors, so we don't need to
                          return liquidateBorrowFresh(msg.sender, borrower, repayAmount, cTokenCollateral);
                      }
                  
                      /**
                       * @notice The liquidator liquidates the borrowers collateral.
                       *  The collateral seized is transferred to the liquidator.
                       * @param borrower The borrower of this cToken to be liquidated
                       * @param liquidator The address repaying the borrow and seizing collateral
                       * @param cTokenCollateral The market in which to seize collateral from the borrower
                       * @param repayAmount The amount of the underlying borrowed asset to repay
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function liquidateBorrowFresh(address liquidator, address borrower, uint repayAmount, CToken cTokenCollateral) internal returns (uint) {
                          /* Fail if liquidate not allowed */
                          uint allowed = comptroller.liquidateBorrowAllowed(address(this), address(cTokenCollateral), liquidator, borrower, repayAmount);
                          if (allowed != 0) {
                              return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.LIQUIDATE_COMPTROLLER_REJECTION, allowed);
                          }
                  
                          /* Verify market's block number equals current block number */
                          if (accrualBlockNumber != getBlockNumber()) {
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.LIQUIDATE_FRESHNESS_CHECK);
                          }
                  
                          /* Verify cTokenCollateral market's block number equals current block number */
                          if (cTokenCollateral.accrualBlockNumber() != getBlockNumber()) {
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.LIQUIDATE_COLLATERAL_FRESHNESS_CHECK);
                          }
                  
                          /* Fail if borrower = liquidator */
                          if (borrower == liquidator) {
                              return fail(Error.INVALID_ACCOUNT_PAIR, FailureInfo.LIQUIDATE_LIQUIDATOR_IS_BORROWER);
                          }
                  
                          /* Fail if repayAmount = 0 */
                          if (repayAmount == 0) {
                              return fail(Error.INVALID_CLOSE_AMOUNT_REQUESTED, FailureInfo.LIQUIDATE_CLOSE_AMOUNT_IS_ZERO);
                          }
                  
                          /* Fail if repayAmount = -1 */
                          if (repayAmount == uint(-1)) {
                              return fail(Error.INVALID_CLOSE_AMOUNT_REQUESTED, FailureInfo.LIQUIDATE_CLOSE_AMOUNT_IS_UINT_MAX);
                          }
                  
                          /* We calculate the number of collateral tokens that will be seized */
                          (uint amountSeizeError, uint seizeTokens) = comptroller.liquidateCalculateSeizeTokens(address(this), address(cTokenCollateral), repayAmount);
                          if (amountSeizeError != 0) {
                              return failOpaque(Error.COMPTROLLER_CALCULATION_ERROR, FailureInfo.LIQUIDATE_COMPTROLLER_CALCULATE_AMOUNT_SEIZE_FAILED, amountSeizeError);
                          }
                  
                          /* Fail if seizeTokens > borrower collateral token balance */
                          if (seizeTokens > cTokenCollateral.balanceOf(borrower)) {
                              return fail(Error.TOKEN_INSUFFICIENT_BALANCE, FailureInfo.LIQUIDATE_SEIZE_TOO_MUCH);
                          }
                  
                          /* Fail if repayBorrow fails */
                          uint repayBorrowError = repayBorrowFresh(liquidator, borrower, repayAmount);
                          if (repayBorrowError != uint(Error.NO_ERROR)) {
                              return fail(Error(repayBorrowError), FailureInfo.LIQUIDATE_REPAY_BORROW_FRESH_FAILED);
                          }
                  
                          /* Revert if seize tokens fails (since we cannot be sure of side effects) */
                          uint seizeError = cTokenCollateral.seize(liquidator, borrower, seizeTokens);
                          require(seizeError == uint(Error.NO_ERROR), "token seizure failed");
                  
                          /* We emit a LiquidateBorrow event */
                          emit LiquidateBorrow(liquidator, borrower, repayAmount, address(cTokenCollateral), seizeTokens);
                  
                          /* We call the defense hook */
                          comptroller.liquidateBorrowVerify(address(this), address(cTokenCollateral), liquidator, borrower, repayAmount, seizeTokens);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice Transfers collateral tokens (this market) to the liquidator.
                       * @dev Will fail unless called by another cToken during the process of liquidation.
                       *  Its absolutely critical to use msg.sender as the borrowed cToken and not a parameter.
                       * @param liquidator The account receiving seized collateral
                       * @param borrower The account having collateral seized
                       * @param seizeTokens The number of cTokens to seize
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function seize(address liquidator, address borrower, uint seizeTokens) external nonReentrant returns (uint) {
                          /* Fail if seize not allowed */
                          uint allowed = comptroller.seizeAllowed(address(this), msg.sender, liquidator, borrower, seizeTokens);
                          if (allowed != 0) {
                              return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.LIQUIDATE_SEIZE_COMPTROLLER_REJECTION, allowed);
                          }
                  
                          /* Fail if borrower = liquidator */
                          if (borrower == liquidator) {
                              return fail(Error.INVALID_ACCOUNT_PAIR, FailureInfo.LIQUIDATE_SEIZE_LIQUIDATOR_IS_BORROWER);
                          }
                  
                          MathError mathErr;
                          uint borrowerTokensNew;
                          uint liquidatorTokensNew;
                  
                          /*
                           * We calculate the new borrower and liquidator token balances, failing on underflow/overflow:
                           *  borrowerTokensNew = accountTokens[borrower] - seizeTokens
                           *  liquidatorTokensNew = accountTokens[liquidator] + seizeTokens
                           */
                          (mathErr, borrowerTokensNew) = subUInt(accountTokens[borrower], seizeTokens);
                          if (mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.LIQUIDATE_SEIZE_BALANCE_DECREMENT_FAILED, uint(mathErr));
                          }
                  
                          (mathErr, liquidatorTokensNew) = addUInt(accountTokens[liquidator], seizeTokens);
                          if (mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.LIQUIDATE_SEIZE_BALANCE_INCREMENT_FAILED, uint(mathErr));
                          }
                  
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                  
                          /* We write the previously calculated values into storage */
                          accountTokens[borrower] = borrowerTokensNew;
                          accountTokens[liquidator] = liquidatorTokensNew;
                  
                          /* Emit a Transfer event */
                          emit Transfer(borrower, liquidator, seizeTokens);
                  
                          /* We call the defense hook */
                          comptroller.seizeVerify(address(this), msg.sender, liquidator, borrower, seizeTokens);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                  
                      /*** Admin Functions ***/
                  
                      /**
                        * @notice Begins transfer of admin rights. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
                        * @dev Admin function to begin change of admin. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
                        * @param newPendingAdmin New pending admin.
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        *
                        * TODO: Should we add a second arg to verify, like a checksum of `newAdmin` address?
                        */
                      function _setPendingAdmin(address payable newPendingAdmin) external returns (uint) {
                          // Check caller = admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_PENDING_ADMIN_OWNER_CHECK);
                          }
                  
                          // Save current value, if any, for inclusion in log
                          address oldPendingAdmin = pendingAdmin;
                  
                          // Store pendingAdmin with value newPendingAdmin
                          pendingAdmin = newPendingAdmin;
                  
                          // Emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin)
                          emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                        * @notice Accepts transfer of admin rights. msg.sender must be pendingAdmin
                        * @dev Admin function for pending admin to accept role and update admin
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function _acceptAdmin() external returns (uint) {
                          // Check caller is pendingAdmin and pendingAdmin ≠ address(0)
                          if (msg.sender != pendingAdmin || msg.sender == address(0)) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.ACCEPT_ADMIN_PENDING_ADMIN_CHECK);
                          }
                  
                          // Save current values for inclusion in log
                          address oldAdmin = admin;
                          address oldPendingAdmin = pendingAdmin;
                  
                          // Store admin with value pendingAdmin
                          admin = pendingAdmin;
                  
                          // Clear the pending value
                          pendingAdmin = address(0);
                  
                          emit NewAdmin(oldAdmin, admin);
                          emit NewPendingAdmin(oldPendingAdmin, pendingAdmin);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                        * @notice Sets a new comptroller for the market
                        * @dev Admin function to set a new comptroller
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function _setComptroller(ComptrollerInterface newComptroller) public returns (uint) {
                          // Check caller is admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_COMPTROLLER_OWNER_CHECK);
                          }
                  
                          ComptrollerInterface oldComptroller = comptroller;
                          // Ensure invoke comptroller.isComptroller() returns true
                          require(newComptroller.isComptroller(), "marker method returned false");
                  
                          // Set market's comptroller to newComptroller
                          comptroller = newComptroller;
                  
                          // Emit NewComptroller(oldComptroller, newComptroller)
                          emit NewComptroller(oldComptroller, newComptroller);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                        * @notice accrues interest and sets a new reserve factor for the protocol using _setReserveFactorFresh
                        * @dev Admin function to accrue interest and set a new reserve factor
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function _setReserveFactor(uint newReserveFactorMantissa) external nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted reserve factor change failed.
                              return fail(Error(error), FailureInfo.SET_RESERVE_FACTOR_ACCRUE_INTEREST_FAILED);
                          }
                          // _setReserveFactorFresh emits reserve-factor-specific logs on errors, so we don't need to.
                          return _setReserveFactorFresh(newReserveFactorMantissa);
                      }
                  
                      /**
                        * @notice Sets a new reserve factor for the protocol (*requires fresh interest accrual)
                        * @dev Admin function to set a new reserve factor
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function _setReserveFactorFresh(uint newReserveFactorMantissa) internal returns (uint) {
                          // Check caller is admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_RESERVE_FACTOR_ADMIN_CHECK);
                          }
                  
                          // Verify market's block number equals current block number
                          if (accrualBlockNumber != getBlockNumber()) {
                              // TODO: static_assert + no error code?
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.SET_RESERVE_FACTOR_FRESH_CHECK);
                          }
                  
                          // Check newReserveFactor ≤ maxReserveFactor
                          if (newReserveFactorMantissa > reserveFactorMaxMantissa) {
                              return fail(Error.BAD_INPUT, FailureInfo.SET_RESERVE_FACTOR_BOUNDS_CHECK);
                          }
                  
                          uint oldReserveFactorMantissa = reserveFactorMantissa;
                          reserveFactorMantissa = newReserveFactorMantissa;
                  
                          emit NewReserveFactor(oldReserveFactorMantissa, newReserveFactorMantissa);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice Accrues interest and reduces reserves by transferring to admin
                       * @param reduceAmount Amount of reduction to reserves
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function _reduceReserves(uint reduceAmount) external nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted reduce reserves failed.
                              return fail(Error(error), FailureInfo.REDUCE_RESERVES_ACCRUE_INTEREST_FAILED);
                          }
                          // _reduceReservesFresh emits reserve-reduction-specific logs on errors, so we don't need to.
                          return _reduceReservesFresh(reduceAmount);
                      }
                  
                      /**
                       * @notice Reduces reserves by transferring to admin
                       * @dev Requires fresh interest accrual
                       * @param reduceAmount Amount of reduction to reserves
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function _reduceReservesFresh(uint reduceAmount) internal returns (uint) {
                          Error err;
                          // totalReserves - reduceAmount
                          uint totalReservesNew;
                  
                          // Check caller is admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.REDUCE_RESERVES_ADMIN_CHECK);
                          }
                  
                          // We fail gracefully unless market's block number equals current block number
                          if (accrualBlockNumber != getBlockNumber()) {
                              // TODO: static_assert + no error code?
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.REDUCE_RESERVES_FRESH_CHECK);
                          }
                  
                          // Fail gracefully if protocol has insufficient underlying cash
                          if (getCashPrior() < reduceAmount) {
                              return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.REDUCE_RESERVES_CASH_NOT_AVAILABLE);
                          }
                  
                          // Check reduceAmount ≤ reserves[n] (totalReserves)
                          // TODO: I'm following the spec literally here but I think we should we just use SafeMath instead and fail on an error (which would be underflow)
                          if (reduceAmount > totalReserves) {
                              return fail(Error.BAD_INPUT, FailureInfo.REDUCE_RESERVES_VALIDATION);
                          }
                  
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                  
                          totalReservesNew = totalReserves - reduceAmount;
                          // We checked reduceAmount <= totalReserves above, so this should never revert.
                          require(totalReservesNew <= totalReserves, "reduce reserves unexpected underflow");
                  
                          // Store reserves[n+1] = reserves[n] - reduceAmount
                          totalReserves = totalReservesNew;
                  
                          // invoke doTransferOut(reduceAmount, admin)
                          err = doTransferOut(admin, reduceAmount);
                          // we revert on the failure of this command
                          require(err == Error.NO_ERROR, "reduce reserves transfer out failed");
                  
                          emit ReservesReduced(admin, reduceAmount, totalReservesNew);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @notice accrues interest and updates the interest rate model using _setInterestRateModelFresh
                       * @dev Admin function to accrue interest and update the interest rate model
                       * @param newInterestRateModel the new interest rate model to use
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function _setInterestRateModel(InterestRateModel newInterestRateModel) public returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted change of interest rate model failed
                              return fail(Error(error), FailureInfo.SET_INTEREST_RATE_MODEL_ACCRUE_INTEREST_FAILED);
                          }
                          // _setInterestRateModelFresh emits interest-rate-model-update-specific logs on errors, so we don't need to.
                          return _setInterestRateModelFresh(newInterestRateModel);
                      }
                  
                      /**
                       * @notice updates the interest rate model (*requires fresh interest accrual)
                       * @dev Admin function to update the interest rate model
                       * @param newInterestRateModel the new interest rate model to use
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function _setInterestRateModelFresh(InterestRateModel newInterestRateModel) internal returns (uint) {
                  
                          // Used to store old model for use in the event that is emitted on success
                          InterestRateModel oldInterestRateModel;
                  
                          // Check caller is admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_INTEREST_RATE_MODEL_OWNER_CHECK);
                          }
                  
                          // We fail gracefully unless market's block number equals current block number
                          if (accrualBlockNumber != getBlockNumber()) {
                              // TODO: static_assert + no error code?
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.SET_INTEREST_RATE_MODEL_FRESH_CHECK);
                          }
                  
                          // Track the market's current interest rate model
                          oldInterestRateModel = interestRateModel;
                  
                          // Ensure invoke newInterestRateModel.isInterestRateModel() returns true
                          require(newInterestRateModel.isInterestRateModel(), "marker method returned false");
                  
                          // Set the interest rate model to newInterestRateModel
                          interestRateModel = newInterestRateModel;
                  
                          // Emit NewMarketInterestRateModel(oldInterestRateModel, newInterestRateModel)
                          emit NewMarketInterestRateModel(oldInterestRateModel, newInterestRateModel);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /*** Safe Token ***/
                  
                      /**
                       * @notice Gets balance of this contract in terms of the underlying
                       * @dev This excludes the value of the current message, if any
                       * @return The quantity of underlying owned by this contract
                       */
                      function getCashPrior() internal view returns (uint);
                  
                      /**
                       * @dev Checks whether or not there is sufficient allowance for this contract to move amount from `from` and
                       *      whether or not `from` has a balance of at least `amount`. Does NOT do a transfer.
                       */
                      function checkTransferIn(address from, uint amount) internal view returns (Error);
                  
                      /**
                       * @dev Performs a transfer in, ideally returning an explanatory error code upon failure rather than reverting.
                       *  If caller has not called `checkTransferIn`, this may revert due to insufficient balance or insufficient allowance.
                       *  If caller has called `checkTransferIn` successfully, this should not revert in normal conditions.
                       */
                      function doTransferIn(address from, uint amount) internal returns (Error);
                  
                      /**
                       * @dev Performs a transfer out, ideally returning an explanatory error code upon failure tather than reverting.
                       *  If caller has not called checked protocol's balance, may revert due to insufficient cash held in the contract.
                       *  If caller has checked protocol's balance, and verified it is >= amount, this should not revert in normal conditions.
                       */
                      function doTransferOut(address payable to, uint amount) internal returns (Error);
                  }
                  
                  // File: contracts/PriceOracle.sol
                  
                  pragma solidity ^0.5.8;
                  
                  
                  interface PriceOracle {
                      /**
                       * @notice Indicator that this is a PriceOracle contract (for inspection)
                       */
                      function isPriceOracle() external pure returns (bool);
                  
                      /**
                        * @notice Get the underlying price of a cToken asset
                        * @param cToken The cToken to get the underlying price of
                        * @return The underlying asset price mantissa (scaled by 1e18).
                        *  Zero means the price is unavailable.
                        */
                      function getUnderlyingPrice(CToken cToken) external view returns (uint);
                  }
                  
                  // File: contracts/ComptrollerStorage.sol
                  
                  pragma solidity ^0.5.8;
                  
                  
                  
                  contract UnitrollerAdminStorage {
                      /**
                      * @notice Administrator for this contract
                      */
                      address public admin;
                  
                      /**
                      * @notice Pending administrator for this contract
                      */
                      address public pendingAdmin;
                  
                      /**
                      * @notice Active brains of Unitroller
                      */
                      address public comptrollerImplementation;
                  
                      /**
                      * @notice Pending brains of Unitroller
                      */
                      address public pendingComptrollerImplementation;
                  }
                  
                  contract ComptrollerV1Storage is UnitrollerAdminStorage {
                  
                      /**
                       * @notice Oracle which gives the price of any given asset
                       */
                      PriceOracle public oracle;
                  
                      /**
                       * @notice Multiplier used to calculate the maximum repayAmount when liquidating a borrow
                       */
                      uint public closeFactorMantissa;
                  
                      /**
                       * @notice Multiplier representing the discount on collateral that a liquidator receives
                       */
                      uint public liquidationIncentiveMantissa;
                  
                      /**
                       * @notice Max number of assets a single account can participate in (borrow or use as collateral)
                       */
                      uint public maxAssets;
                  
                      /**
                       * @notice Per-account mapping of "assets you are in", capped by maxAssets
                       */
                      mapping(address => CToken[]) public accountAssets;
                  
                  }
                  
                  // File: contracts/Unitroller.sol
                  
                  pragma solidity ^0.5.8;
                  
                  
                  /**
                   * @title ComptrollerCore
                   * @dev storage for the comptroller will be at this address, and
                   * cTokens should reference this contract rather than a deployed implementation if
                   *
                   */
                  contract Unitroller is UnitrollerAdminStorage, ComptrollerErrorReporter {
                  
                      /**
                        * @notice Emitted when pendingComptrollerImplementation is changed
                        */
                      event NewPendingImplementation(address oldPendingImplementation, address newPendingImplementation);
                  
                      /**
                        * @notice Emitted when pendingComptrollerImplementation is accepted, which means comptroller implementation is updated
                        */
                      event NewImplementation(address oldImplementation, address newImplementation);
                  
                      /**
                        * @notice Emitted when pendingAdmin is changed
                        */
                      event NewPendingAdmin(address oldPendingAdmin, address newPendingAdmin);
                  
                      /**
                        * @notice Emitted when pendingAdmin is accepted, which means admin is updated
                        */
                      event NewAdmin(address oldAdmin, address newAdmin);
                  
                      constructor() public {
                          // Set admin to caller
                          admin = msg.sender;
                      }
                  
                      /*** Admin Functions ***/
                      function _setPendingImplementation(address newPendingImplementation) public returns (uint) {
                  
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_PENDING_IMPLEMENTATION_OWNER_CHECK);
                          }
                  
                          address oldPendingImplementation = pendingComptrollerImplementation;
                  
                          pendingComptrollerImplementation = newPendingImplementation;
                  
                          emit NewPendingImplementation(oldPendingImplementation, pendingComptrollerImplementation);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                      * @notice Accepts new implementation of comptroller. msg.sender must be pendingImplementation
                      * @dev Admin function for new implementation to accept it's role as implementation
                      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                      */
                      function _acceptImplementation() public returns (uint) {
                          // Check caller is pendingImplementation and pendingImplementation ≠ address(0)
                          if (msg.sender != pendingComptrollerImplementation || pendingComptrollerImplementation == address(0)) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.ACCEPT_PENDING_IMPLEMENTATION_ADDRESS_CHECK);
                          }
                  
                          // Save current values for inclusion in log
                          address oldImplementation = comptrollerImplementation;
                          address oldPendingImplementation = pendingComptrollerImplementation;
                  
                          comptrollerImplementation = pendingComptrollerImplementation;
                  
                          pendingComptrollerImplementation = address(0);
                  
                          emit NewImplementation(oldImplementation, comptrollerImplementation);
                          emit NewPendingImplementation(oldPendingImplementation, pendingComptrollerImplementation);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                  
                      /**
                        * @notice Begins transfer of admin rights. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
                        * @dev Admin function to begin change of admin. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
                        * @param newPendingAdmin New pending admin.
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        *
                        * TODO: Should we add a second arg to verify, like a checksum of `newAdmin` address?
                        */
                      function _setPendingAdmin(address newPendingAdmin) public returns (uint) {
                          // Check caller = admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_PENDING_ADMIN_OWNER_CHECK);
                          }
                  
                          // Save current value, if any, for inclusion in log
                          address oldPendingAdmin = pendingAdmin;
                  
                          // Store pendingAdmin with value newPendingAdmin
                          pendingAdmin = newPendingAdmin;
                  
                          // Emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin)
                          emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                        * @notice Accepts transfer of admin rights. msg.sender must be pendingAdmin
                        * @dev Admin function for pending admin to accept role and update admin
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function _acceptAdmin() public returns (uint) {
                          // Check caller is pendingAdmin and pendingAdmin ≠ address(0)
                          if (msg.sender != pendingAdmin || msg.sender == address(0)) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.ACCEPT_ADMIN_PENDING_ADMIN_CHECK);
                          }
                  
                          // Save current values for inclusion in log
                          address oldAdmin = admin;
                          address oldPendingAdmin = pendingAdmin;
                  
                          // Store admin with value pendingAdmin
                          admin = pendingAdmin;
                  
                          // Clear the pending value
                          pendingAdmin = address(0);
                  
                          emit NewAdmin(oldAdmin, admin);
                          emit NewPendingAdmin(oldPendingAdmin, pendingAdmin);
                  
                          return uint(Error.NO_ERROR);
                      }
                  
                      /**
                       * @dev Delegates execution to an implementation contract.
                       * It returns to the external caller whatever the implementation returns
                       * or forwards reverts.
                       */
                      function () payable external {
                          // delegate all other functions to current implementation
                          (bool success, ) = comptrollerImplementation.delegatecall(msg.data);
                  
                          // solium-disable-next-line security/no-inline-assembly
                          assembly {
                                let free_mem_ptr := mload(0x40)
                                returndatacopy(free_mem_ptr, 0, returndatasize)
                  
                                switch success
                                case 0 { revert(free_mem_ptr, returndatasize) }
                                default { return(free_mem_ptr, returndatasize) }
                          }
                      }
                  }
                  

                  File 6 of 6: Comptroller
                  pragma solidity ^0.5.16;
                  import "./ComptrollerInterface.sol";
                  import "./CTokenInterfaces.sol";
                  import "./ErrorReporter.sol";
                  import "./Exponential.sol";
                  import "./EIP20Interface.sol";
                  import "./InterestRateModel.sol";
                  /**
                   * @title Compound's CToken Contract
                   * @notice Abstract base for CTokens
                   * @author Compound
                   */
                  contract CToken is CTokenInterface, Exponential, TokenErrorReporter {
                      /**
                       * @notice Initialize the money market
                       * @param comptroller_ The address of the Comptroller
                       * @param interestRateModel_ The address of the interest rate model
                       * @param initialExchangeRateMantissa_ The initial exchange rate, scaled by 1e18
                       * @param name_ EIP-20 name of this token
                       * @param symbol_ EIP-20 symbol of this token
                       * @param decimals_ EIP-20 decimal precision of this token
                       */
                      function initialize(ComptrollerInterface comptroller_,
                                          InterestRateModel interestRateModel_,
                                          uint initialExchangeRateMantissa_,
                                          string memory name_,
                                          string memory symbol_,
                                          uint8 decimals_) public {
                          require(msg.sender == admin, "only admin may initialize the market");
                          require(accrualBlockNumber == 0 && borrowIndex == 0, "market may only be initialized once");
                          // Set initial exchange rate
                          initialExchangeRateMantissa = initialExchangeRateMantissa_;
                          require(initialExchangeRateMantissa > 0, "initial exchange rate must be greater than zero.");
                          // Set the comptroller
                          uint err = _setComptroller(comptroller_);
                          require(err == uint(Error.NO_ERROR), "setting comptroller failed");
                          // Initialize block number and borrow index (block number mocks depend on comptroller being set)
                          accrualBlockNumber = getBlockNumber();
                          borrowIndex = mantissaOne;
                          // Set the interest rate model (depends on block number / borrow index)
                          err = _setInterestRateModelFresh(interestRateModel_);
                          require(err == uint(Error.NO_ERROR), "setting interest rate model failed");
                          name = name_;
                          symbol = symbol_;
                          decimals = decimals_;
                          // The counter starts true to prevent changing it from zero to non-zero (i.e. smaller cost/refund)
                          _notEntered = true;
                      }
                      /**
                       * @notice Transfer `tokens` tokens from `src` to `dst` by `spender`
                       * @dev Called by both `transfer` and `transferFrom` internally
                       * @param spender The address of the account performing the transfer
                       * @param src The address of the source account
                       * @param dst The address of the destination account
                       * @param tokens The number of tokens to transfer
                       * @return Whether or not the transfer succeeded
                       */
                      function transferTokens(address spender, address src, address dst, uint tokens) internal returns (uint) {
                          /* Fail if transfer not allowed */
                          uint allowed = comptroller.transferAllowed(address(this), src, dst, tokens);
                          if (allowed != 0) {
                              return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.TRANSFER_COMPTROLLER_REJECTION, allowed);
                          }
                          /* Do not allow self-transfers */
                          if (src == dst) {
                              return fail(Error.BAD_INPUT, FailureInfo.TRANSFER_NOT_ALLOWED);
                          }
                          /* Get the allowance, infinite for the account owner */
                          uint startingAllowance = 0;
                          if (spender == src) {
                              startingAllowance = uint(-1);
                          } else {
                              startingAllowance = transferAllowances[src][spender];
                          }
                          /* Do the calculations, checking for {under,over}flow */
                          MathError mathErr;
                          uint allowanceNew;
                          uint srcTokensNew;
                          uint dstTokensNew;
                          (mathErr, allowanceNew) = subUInt(startingAllowance, tokens);
                          if (mathErr != MathError.NO_ERROR) {
                              return fail(Error.MATH_ERROR, FailureInfo.TRANSFER_NOT_ALLOWED);
                          }
                          (mathErr, srcTokensNew) = subUInt(accountTokens[src], tokens);
                          if (mathErr != MathError.NO_ERROR) {
                              return fail(Error.MATH_ERROR, FailureInfo.TRANSFER_NOT_ENOUGH);
                          }
                          (mathErr, dstTokensNew) = addUInt(accountTokens[dst], tokens);
                          if (mathErr != MathError.NO_ERROR) {
                              return fail(Error.MATH_ERROR, FailureInfo.TRANSFER_TOO_MUCH);
                          }
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                          accountTokens[src] = srcTokensNew;
                          accountTokens[dst] = dstTokensNew;
                          /* Eat some of the allowance (if necessary) */
                          if (startingAllowance != uint(-1)) {
                              transferAllowances[src][spender] = allowanceNew;
                          }
                          /* We emit a Transfer event */
                          emit Transfer(src, dst, tokens);
                          // unused function
                          // comptroller.transferVerify(address(this), src, dst, tokens);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                       * @notice Transfer `amount` tokens from `msg.sender` to `dst`
                       * @param dst The address of the destination account
                       * @param amount The number of tokens to transfer
                       * @return Whether or not the transfer succeeded
                       */
                      function transfer(address dst, uint256 amount) external nonReentrant returns (bool) {
                          return transferTokens(msg.sender, msg.sender, dst, amount) == uint(Error.NO_ERROR);
                      }
                      /**
                       * @notice Transfer `amount` tokens from `src` to `dst`
                       * @param src The address of the source account
                       * @param dst The address of the destination account
                       * @param amount The number of tokens to transfer
                       * @return Whether or not the transfer succeeded
                       */
                      function transferFrom(address src, address dst, uint256 amount) external nonReentrant returns (bool) {
                          return transferTokens(msg.sender, src, dst, amount) == uint(Error.NO_ERROR);
                      }
                      /**
                       * @notice Approve `spender` to transfer up to `amount` from `src`
                       * @dev This will overwrite the approval amount for `spender`
                       *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
                       * @param spender The address of the account which may transfer tokens
                       * @param amount The number of tokens that are approved (-1 means infinite)
                       * @return Whether or not the approval succeeded
                       */
                      function approve(address spender, uint256 amount) external returns (bool) {
                          address src = msg.sender;
                          transferAllowances[src][spender] = amount;
                          emit Approval(src, spender, amount);
                          return true;
                      }
                      /**
                       * @notice Get the current allowance from `owner` for `spender`
                       * @param owner The address of the account which owns the tokens to be spent
                       * @param spender The address of the account which may transfer tokens
                       * @return The number of tokens allowed to be spent (-1 means infinite)
                       */
                      function allowance(address owner, address spender) external view returns (uint256) {
                          return transferAllowances[owner][spender];
                      }
                      /**
                       * @notice Get the token balance of the `owner`
                       * @param owner The address of the account to query
                       * @return The number of tokens owned by `owner`
                       */
                      function balanceOf(address owner) external view returns (uint256) {
                          return accountTokens[owner];
                      }
                      /**
                       * @notice Get the underlying balance of the `owner`
                       * @dev This also accrues interest in a transaction
                       * @param owner The address of the account to query
                       * @return The amount of underlying owned by `owner`
                       */
                      function balanceOfUnderlying(address owner) external returns (uint) {
                          Exp memory exchangeRate = Exp({mantissa: exchangeRateCurrent()});
                          (MathError mErr, uint balance) = mulScalarTruncate(exchangeRate, accountTokens[owner]);
                          require(mErr == MathError.NO_ERROR, "balance could not be calculated");
                          return balance;
                      }
                      /**
                       * @notice Get a snapshot of the account's balances, and the cached exchange rate
                       * @dev This is used by comptroller to more efficiently perform liquidity checks.
                       * @param account Address of the account to snapshot
                       * @return (possible error, token balance, borrow balance, exchange rate mantissa)
                       */
                      function getAccountSnapshot(address account) external view returns (uint, uint, uint, uint) {
                          uint cTokenBalance = accountTokens[account];
                          uint borrowBalance;
                          uint exchangeRateMantissa;
                          MathError mErr;
                          (mErr, borrowBalance) = borrowBalanceStoredInternal(account);
                          if (mErr != MathError.NO_ERROR) {
                              return (uint(Error.MATH_ERROR), 0, 0, 0);
                          }
                          (mErr, exchangeRateMantissa) = exchangeRateStoredInternal();
                          if (mErr != MathError.NO_ERROR) {
                              return (uint(Error.MATH_ERROR), 0, 0, 0);
                          }
                          return (uint(Error.NO_ERROR), cTokenBalance, borrowBalance, exchangeRateMantissa);
                      }
                      /**
                       * @dev Function to simply retrieve block number
                       *  This exists mainly for inheriting test contracts to stub this result.
                       */
                      function getBlockNumber() internal view returns (uint) {
                          return block.number;
                      }
                      /**
                       * @notice Returns the current per-block borrow interest rate for this cToken
                       * @return The borrow interest rate per block, scaled by 1e18
                       */
                      function borrowRatePerBlock() external view returns (uint) {
                          return interestRateModel.getBorrowRate(getCashPrior(), totalBorrows, totalReserves);
                      }
                      /**
                       * @notice Returns the current per-block supply interest rate for this cToken
                       * @return The supply interest rate per block, scaled by 1e18
                       */
                      function supplyRatePerBlock() external view returns (uint) {
                          return interestRateModel.getSupplyRate(getCashPrior(), totalBorrows, totalReserves, reserveFactorMantissa);
                      }
                      /**
                       * @notice Returns the current total borrows plus accrued interest
                       * @return The total borrows with interest
                       */
                      function totalBorrowsCurrent() external nonReentrant returns (uint) {
                          require(accrueInterest() == uint(Error.NO_ERROR), "accrue interest failed");
                          return totalBorrows;
                      }
                      /**
                       * @notice Accrue interest to updated borrowIndex and then calculate account's borrow balance using the updated borrowIndex
                       * @param account The address whose balance should be calculated after updating borrowIndex
                       * @return The calculated balance
                       */
                      function borrowBalanceCurrent(address account) external nonReentrant returns (uint) {
                          require(accrueInterest() == uint(Error.NO_ERROR), "accrue interest failed");
                          return borrowBalanceStored(account);
                      }
                      /**
                       * @notice Return the borrow balance of account based on stored data
                       * @param account The address whose balance should be calculated
                       * @return The calculated balance
                       */
                      function borrowBalanceStored(address account) public view returns (uint) {
                          (MathError err, uint result) = borrowBalanceStoredInternal(account);
                          require(err == MathError.NO_ERROR, "borrowBalanceStored: borrowBalanceStoredInternal failed");
                          return result;
                      }
                      /**
                       * @notice Return the borrow balance of account based on stored data
                       * @param account The address whose balance should be calculated
                       * @return (error code, the calculated balance or 0 if error code is non-zero)
                       */
                      function borrowBalanceStoredInternal(address account) internal view returns (MathError, uint) {
                          /* Note: we do not assert that the market is up to date */
                          MathError mathErr;
                          uint principalTimesIndex;
                          uint result;
                          /* Get borrowBalance and borrowIndex */
                          BorrowSnapshot storage borrowSnapshot = accountBorrows[account];
                          /* If borrowBalance = 0 then borrowIndex is likely also 0.
                           * Rather than failing the calculation with a division by 0, we immediately return 0 in this case.
                           */
                          if (borrowSnapshot.principal == 0) {
                              return (MathError.NO_ERROR, 0);
                          }
                          /* Calculate new borrow balance using the interest index:
                           *  recentBorrowBalance = borrower.borrowBalance * market.borrowIndex / borrower.borrowIndex
                           */
                          (mathErr, principalTimesIndex) = mulUInt(borrowSnapshot.principal, borrowIndex);
                          if (mathErr != MathError.NO_ERROR) {
                              return (mathErr, 0);
                          }
                          (mathErr, result) = divUInt(principalTimesIndex, borrowSnapshot.interestIndex);
                          if (mathErr != MathError.NO_ERROR) {
                              return (mathErr, 0);
                          }
                          return (MathError.NO_ERROR, result);
                      }
                      /**
                       * @notice Accrue interest then return the up-to-date exchange rate
                       * @return Calculated exchange rate scaled by 1e18
                       */
                      function exchangeRateCurrent() public nonReentrant returns (uint) {
                          require(accrueInterest() == uint(Error.NO_ERROR), "accrue interest failed");
                          return exchangeRateStored();
                      }
                      /**
                       * @notice Calculates the exchange rate from the underlying to the CToken
                       * @dev This function does not accrue interest before calculating the exchange rate
                       * @return Calculated exchange rate scaled by 1e18
                       */
                      function exchangeRateStored() public view returns (uint) {
                          (MathError err, uint result) = exchangeRateStoredInternal();
                          require(err == MathError.NO_ERROR, "exchangeRateStored: exchangeRateStoredInternal failed");
                          return result;
                      }
                      /**
                       * @notice Calculates the exchange rate from the underlying to the CToken
                       * @dev This function does not accrue interest before calculating the exchange rate
                       * @return (error code, calculated exchange rate scaled by 1e18)
                       */
                      function exchangeRateStoredInternal() internal view returns (MathError, uint) {
                          uint _totalSupply = totalSupply;
                          if (_totalSupply == 0) {
                              /*
                               * If there are no tokens minted:
                               *  exchangeRate = initialExchangeRate
                               */
                              return (MathError.NO_ERROR, initialExchangeRateMantissa);
                          } else {
                              /*
                               * Otherwise:
                               *  exchangeRate = (totalCash + totalBorrows - totalReserves) / totalSupply
                               */
                              uint totalCash = getCashPrior();
                              uint cashPlusBorrowsMinusReserves;
                              Exp memory exchangeRate;
                              MathError mathErr;
                              (mathErr, cashPlusBorrowsMinusReserves) = addThenSubUInt(totalCash, totalBorrows, totalReserves);
                              if (mathErr != MathError.NO_ERROR) {
                                  return (mathErr, 0);
                              }
                              (mathErr, exchangeRate) = getExp(cashPlusBorrowsMinusReserves, _totalSupply);
                              if (mathErr != MathError.NO_ERROR) {
                                  return (mathErr, 0);
                              }
                              return (MathError.NO_ERROR, exchangeRate.mantissa);
                          }
                      }
                      /**
                       * @notice Get cash balance of this cToken in the underlying asset
                       * @return The quantity of underlying asset owned by this contract
                       */
                      function getCash() external view returns (uint) {
                          return getCashPrior();
                      }
                      /**
                       * @notice Applies accrued interest to total borrows and reserves
                       * @dev This calculates interest accrued from the last checkpointed block
                       *   up to the current block and writes new checkpoint to storage.
                       */
                      function accrueInterest() public returns (uint) {
                          /* Remember the initial block number */
                          uint currentBlockNumber = getBlockNumber();
                          uint accrualBlockNumberPrior = accrualBlockNumber;
                          /* Short-circuit accumulating 0 interest */
                          if (accrualBlockNumberPrior == currentBlockNumber) {
                              return uint(Error.NO_ERROR);
                          }
                          /* Read the previous values out of storage */
                          uint cashPrior = getCashPrior();
                          uint borrowsPrior = totalBorrows;
                          uint reservesPrior = totalReserves;
                          uint borrowIndexPrior = borrowIndex;
                          /* Calculate the current borrow interest rate */
                          uint borrowRateMantissa = interestRateModel.getBorrowRate(cashPrior, borrowsPrior, reservesPrior);
                          require(borrowRateMantissa <= borrowRateMaxMantissa, "borrow rate is absurdly high");
                          /* Calculate the number of blocks elapsed since the last accrual */
                          (MathError mathErr, uint blockDelta) = subUInt(currentBlockNumber, accrualBlockNumberPrior);
                          require(mathErr == MathError.NO_ERROR, "could not calculate block delta");
                          /*
                           * Calculate the interest accumulated into borrows and reserves and the new index:
                           *  simpleInterestFactor = borrowRate * blockDelta
                           *  interestAccumulated = simpleInterestFactor * totalBorrows
                           *  totalBorrowsNew = interestAccumulated + totalBorrows
                           *  totalReservesNew = interestAccumulated * reserveFactor + totalReserves
                           *  borrowIndexNew = simpleInterestFactor * borrowIndex + borrowIndex
                           */
                          Exp memory simpleInterestFactor;
                          uint interestAccumulated;
                          uint totalBorrowsNew;
                          uint totalReservesNew;
                          uint borrowIndexNew;
                          (mathErr, simpleInterestFactor) = mulScalar(Exp({mantissa: borrowRateMantissa}), blockDelta);
                          if (mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_SIMPLE_INTEREST_FACTOR_CALCULATION_FAILED, uint(mathErr));
                          }
                          (mathErr, interestAccumulated) = mulScalarTruncate(simpleInterestFactor, borrowsPrior);
                          if (mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_ACCUMULATED_INTEREST_CALCULATION_FAILED, uint(mathErr));
                          }
                          (mathErr, totalBorrowsNew) = addUInt(interestAccumulated, borrowsPrior);
                          if (mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_NEW_TOTAL_BORROWS_CALCULATION_FAILED, uint(mathErr));
                          }
                          (mathErr, totalReservesNew) = mulScalarTruncateAddUInt(Exp({mantissa: reserveFactorMantissa}), interestAccumulated, reservesPrior);
                          if (mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_NEW_TOTAL_RESERVES_CALCULATION_FAILED, uint(mathErr));
                          }
                          (mathErr, borrowIndexNew) = mulScalarTruncateAddUInt(simpleInterestFactor, borrowIndexPrior, borrowIndexPrior);
                          if (mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.ACCRUE_INTEREST_NEW_BORROW_INDEX_CALCULATION_FAILED, uint(mathErr));
                          }
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                          /* We write the previously calculated values into storage */
                          accrualBlockNumber = currentBlockNumber;
                          borrowIndex = borrowIndexNew;
                          totalBorrows = totalBorrowsNew;
                          totalReserves = totalReservesNew;
                          /* We emit an AccrueInterest event */
                          emit AccrueInterest(cashPrior, interestAccumulated, borrowIndexNew, totalBorrowsNew);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                       * @notice Sender supplies assets into the market and receives cTokens in exchange
                       * @dev Accrues interest whether or not the operation succeeds, unless reverted
                       * @param mintAmount The amount of the underlying asset to supply
                       * @return (uint, uint) An error code (0=success, otherwise a failure, see ErrorReporter.sol), and the actual mint amount.
                       */
                      function mintInternal(uint mintAmount) internal nonReentrant returns (uint, uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
                              return (fail(Error(error), FailureInfo.MINT_ACCRUE_INTEREST_FAILED), 0);
                          }
                          // mintFresh emits the actual Mint event if successful and logs on errors, so we don't need to
                          return mintFresh(msg.sender, mintAmount);
                      }
                      struct MintLocalVars {
                          Error err;
                          MathError mathErr;
                          uint exchangeRateMantissa;
                          uint mintTokens;
                          uint totalSupplyNew;
                          uint accountTokensNew;
                          uint actualMintAmount;
                      }
                      /**
                       * @notice User supplies assets into the market and receives cTokens in exchange
                       * @dev Assumes interest has already been accrued up to the current block
                       * @param minter The address of the account which is supplying the assets
                       * @param mintAmount The amount of the underlying asset to supply
                       * @return (uint, uint) An error code (0=success, otherwise a failure, see ErrorReporter.sol), and the actual mint amount.
                       */
                      function mintFresh(address minter, uint mintAmount) internal returns (uint, uint) {
                          /* Fail if mint not allowed */
                          uint allowed = comptroller.mintAllowed(address(this), minter, mintAmount);
                          if (allowed != 0) {
                              return (failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.MINT_COMPTROLLER_REJECTION, allowed), 0);
                          }
                          /* Verify market's block number equals current block number */
                          if (accrualBlockNumber != getBlockNumber()) {
                              return (fail(Error.MARKET_NOT_FRESH, FailureInfo.MINT_FRESHNESS_CHECK), 0);
                          }
                          MintLocalVars memory vars;
                          (vars.mathErr, vars.exchangeRateMantissa) = exchangeRateStoredInternal();
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return (failOpaque(Error.MATH_ERROR, FailureInfo.MINT_EXCHANGE_RATE_READ_FAILED, uint(vars.mathErr)), 0);
                          }
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                          /*
                           *  We call `doTransferIn` for the minter and the mintAmount.
                           *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
                           *  `doTransferIn` reverts if anything goes wrong, since we can't be sure if
                           *  side-effects occurred. The function returns the amount actually transferred,
                           *  in case of a fee. On success, the cToken holds an additional `actualMintAmount`
                           *  of cash.
                           */
                          vars.actualMintAmount = doTransferIn(minter, mintAmount);
                          /*
                           * We get the current exchange rate and calculate the number of cTokens to be minted:
                           *  mintTokens = actualMintAmount / exchangeRate
                           */
                          (vars.mathErr, vars.mintTokens) = divScalarByExpTruncate(vars.actualMintAmount, Exp({mantissa: vars.exchangeRateMantissa}));
                          require(vars.mathErr == MathError.NO_ERROR, "MINT_EXCHANGE_CALCULATION_FAILED");
                          /*
                           * We calculate the new total supply of cTokens and minter token balance, checking for overflow:
                           *  totalSupplyNew = totalSupply + mintTokens
                           *  accountTokensNew = accountTokens[minter] + mintTokens
                           */
                          (vars.mathErr, vars.totalSupplyNew) = addUInt(totalSupply, vars.mintTokens);
                          require(vars.mathErr == MathError.NO_ERROR, "MINT_NEW_TOTAL_SUPPLY_CALCULATION_FAILED");
                          (vars.mathErr, vars.accountTokensNew) = addUInt(accountTokens[minter], vars.mintTokens);
                          require(vars.mathErr == MathError.NO_ERROR, "MINT_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED");
                          /* We write previously calculated values into storage */
                          totalSupply = vars.totalSupplyNew;
                          accountTokens[minter] = vars.accountTokensNew;
                          /* We emit a Mint event, and a Transfer event */
                          emit Mint(minter, vars.actualMintAmount, vars.mintTokens);
                          emit Transfer(address(this), minter, vars.mintTokens);
                          /* We call the defense hook */
                          // unused function
                          // comptroller.mintVerify(address(this), minter, vars.actualMintAmount, vars.mintTokens);
                          return (uint(Error.NO_ERROR), vars.actualMintAmount);
                      }
                      /**
                       * @notice Sender redeems cTokens in exchange for the underlying asset
                       * @dev Accrues interest whether or not the operation succeeds, unless reverted
                       * @param redeemTokens The number of cTokens to redeem into underlying
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function redeemInternal(uint redeemTokens) internal nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted redeem failed
                              return fail(Error(error), FailureInfo.REDEEM_ACCRUE_INTEREST_FAILED);
                          }
                          // redeemFresh emits redeem-specific logs on errors, so we don't need to
                          return redeemFresh(msg.sender, redeemTokens, 0);
                      }
                      /**
                       * @notice Sender redeems cTokens in exchange for a specified amount of underlying asset
                       * @dev Accrues interest whether or not the operation succeeds, unless reverted
                       * @param redeemAmount The amount of underlying to receive from redeeming cTokens
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function redeemUnderlyingInternal(uint redeemAmount) internal nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted redeem failed
                              return fail(Error(error), FailureInfo.REDEEM_ACCRUE_INTEREST_FAILED);
                          }
                          // redeemFresh emits redeem-specific logs on errors, so we don't need to
                          return redeemFresh(msg.sender, 0, redeemAmount);
                      }
                      struct RedeemLocalVars {
                          Error err;
                          MathError mathErr;
                          uint exchangeRateMantissa;
                          uint redeemTokens;
                          uint redeemAmount;
                          uint totalSupplyNew;
                          uint accountTokensNew;
                      }
                      /**
                       * @notice User redeems cTokens in exchange for the underlying asset
                       * @dev Assumes interest has already been accrued up to the current block
                       * @param redeemer The address of the account which is redeeming the tokens
                       * @param redeemTokensIn The number of cTokens to redeem into underlying (only one of redeemTokensIn or redeemAmountIn may be non-zero)
                       * @param redeemAmountIn The number of underlying tokens to receive from redeeming cTokens (only one of redeemTokensIn or redeemAmountIn may be non-zero)
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function redeemFresh(address payable redeemer, uint redeemTokensIn, uint redeemAmountIn) internal returns (uint) {
                          require(redeemTokensIn == 0 || redeemAmountIn == 0, "one of redeemTokensIn or redeemAmountIn must be zero");
                          RedeemLocalVars memory vars;
                          /* exchangeRate = invoke Exchange Rate Stored() */
                          (vars.mathErr, vars.exchangeRateMantissa) = exchangeRateStoredInternal();
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_EXCHANGE_RATE_READ_FAILED, uint(vars.mathErr));
                          }
                          /* If redeemTokensIn > 0: */
                          if (redeemTokensIn > 0) {
                              /*
                               * We calculate the exchange rate and the amount of underlying to be redeemed:
                               *  redeemTokens = redeemTokensIn
                               *  redeemAmount = redeemTokensIn x exchangeRateCurrent
                               */
                              vars.redeemTokens = redeemTokensIn;
                              (vars.mathErr, vars.redeemAmount) = mulScalarTruncate(Exp({mantissa: vars.exchangeRateMantissa}), redeemTokensIn);
                              if (vars.mathErr != MathError.NO_ERROR) {
                                  return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_EXCHANGE_TOKENS_CALCULATION_FAILED, uint(vars.mathErr));
                              }
                          } else {
                              /*
                               * We get the current exchange rate and calculate the amount to be redeemed:
                               *  redeemTokens = redeemAmountIn / exchangeRate
                               *  redeemAmount = redeemAmountIn
                               */
                              (vars.mathErr, vars.redeemTokens) = divScalarByExpTruncate(redeemAmountIn, Exp({mantissa: vars.exchangeRateMantissa}));
                              if (vars.mathErr != MathError.NO_ERROR) {
                                  return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_EXCHANGE_AMOUNT_CALCULATION_FAILED, uint(vars.mathErr));
                              }
                              vars.redeemAmount = redeemAmountIn;
                          }
                          /* Fail if redeem not allowed */
                          uint allowed = comptroller.redeemAllowed(address(this), redeemer, vars.redeemTokens);
                          if (allowed != 0) {
                              return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.REDEEM_COMPTROLLER_REJECTION, allowed);
                          }
                          /* Verify market's block number equals current block number */
                          if (accrualBlockNumber != getBlockNumber()) {
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.REDEEM_FRESHNESS_CHECK);
                          }
                          /*
                           * We calculate the new total supply and redeemer balance, checking for underflow:
                           *  totalSupplyNew = totalSupply - redeemTokens
                           *  accountTokensNew = accountTokens[redeemer] - redeemTokens
                           */
                          (vars.mathErr, vars.totalSupplyNew) = subUInt(totalSupply, vars.redeemTokens);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_NEW_TOTAL_SUPPLY_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                          (vars.mathErr, vars.accountTokensNew) = subUInt(accountTokens[redeemer], vars.redeemTokens);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.REDEEM_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                          /* Fail gracefully if protocol has insufficient cash */
                          if (getCashPrior() < vars.redeemAmount) {
                              return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.REDEEM_TRANSFER_OUT_NOT_POSSIBLE);
                          }
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                          /*
                           * We invoke doTransferOut for the redeemer and the redeemAmount.
                           *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
                           *  On success, the cToken has redeemAmount less of cash.
                           *  doTransferOut reverts if anything goes wrong, since we can't be sure if side effects occurred.
                           */
                          doTransferOut(redeemer, vars.redeemAmount);
                          /* We write previously calculated values into storage */
                          totalSupply = vars.totalSupplyNew;
                          accountTokens[redeemer] = vars.accountTokensNew;
                          /* We emit a Transfer event, and a Redeem event */
                          emit Transfer(redeemer, address(this), vars.redeemTokens);
                          emit Redeem(redeemer, vars.redeemAmount, vars.redeemTokens);
                          /* We call the defense hook */
                          comptroller.redeemVerify(address(this), redeemer, vars.redeemAmount, vars.redeemTokens);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                        * @notice Sender borrows assets from the protocol to their own address
                        * @param borrowAmount The amount of the underlying asset to borrow
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function borrowInternal(uint borrowAmount) internal nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
                              return fail(Error(error), FailureInfo.BORROW_ACCRUE_INTEREST_FAILED);
                          }
                          // borrowFresh emits borrow-specific logs on errors, so we don't need to
                          return borrowFresh(msg.sender, borrowAmount);
                      }
                      struct BorrowLocalVars {
                          MathError mathErr;
                          uint accountBorrows;
                          uint accountBorrowsNew;
                          uint totalBorrowsNew;
                      }
                      /**
                        * @notice Users borrow assets from the protocol to their own address
                        * @param borrowAmount The amount of the underlying asset to borrow
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function borrowFresh(address payable borrower, uint borrowAmount) internal returns (uint) {
                          /* Fail if borrow not allowed */
                          uint allowed = comptroller.borrowAllowed(address(this), borrower, borrowAmount);
                          if (allowed != 0) {
                              return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.BORROW_COMPTROLLER_REJECTION, allowed);
                          }
                          /* Verify market's block number equals current block number */
                          if (accrualBlockNumber != getBlockNumber()) {
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.BORROW_FRESHNESS_CHECK);
                          }
                          /* Fail gracefully if protocol has insufficient underlying cash */
                          if (getCashPrior() < borrowAmount) {
                              return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.BORROW_CASH_NOT_AVAILABLE);
                          }
                          BorrowLocalVars memory vars;
                          /*
                           * We calculate the new borrower and total borrow balances, failing on overflow:
                           *  accountBorrowsNew = accountBorrows + borrowAmount
                           *  totalBorrowsNew = totalBorrows + borrowAmount
                           */
                          (vars.mathErr, vars.accountBorrows) = borrowBalanceStoredInternal(borrower);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                          (vars.mathErr, vars.accountBorrowsNew) = addUInt(vars.accountBorrows, borrowAmount);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                          (vars.mathErr, vars.totalBorrowsNew) = addUInt(totalBorrows, borrowAmount);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED, uint(vars.mathErr));
                          }
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                          /*
                           * We invoke doTransferOut for the borrower and the borrowAmount.
                           *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
                           *  On success, the cToken borrowAmount less of cash.
                           *  doTransferOut reverts if anything goes wrong, since we can't be sure if side effects occurred.
                           */
                          doTransferOut(borrower, borrowAmount);
                          /* We write the previously calculated values into storage */
                          accountBorrows[borrower].principal = vars.accountBorrowsNew;
                          accountBorrows[borrower].interestIndex = borrowIndex;
                          totalBorrows = vars.totalBorrowsNew;
                          /* We emit a Borrow event */
                          emit Borrow(borrower, borrowAmount, vars.accountBorrowsNew, vars.totalBorrowsNew);
                          /* We call the defense hook */
                          // unused function
                          // comptroller.borrowVerify(address(this), borrower, borrowAmount);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                       * @notice Sender repays their own borrow
                       * @param repayAmount The amount to repay
                       * @return (uint, uint) An error code (0=success, otherwise a failure, see ErrorReporter.sol), and the actual repayment amount.
                       */
                      function repayBorrowInternal(uint repayAmount) internal nonReentrant returns (uint, uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
                              return (fail(Error(error), FailureInfo.REPAY_BORROW_ACCRUE_INTEREST_FAILED), 0);
                          }
                          // repayBorrowFresh emits repay-borrow-specific logs on errors, so we don't need to
                          return repayBorrowFresh(msg.sender, msg.sender, repayAmount);
                      }
                      /**
                       * @notice Sender repays a borrow belonging to borrower
                       * @param borrower the account with the debt being payed off
                       * @param repayAmount The amount to repay
                       * @return (uint, uint) An error code (0=success, otherwise a failure, see ErrorReporter.sol), and the actual repayment amount.
                       */
                      function repayBorrowBehalfInternal(address borrower, uint repayAmount) internal nonReentrant returns (uint, uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted borrow failed
                              return (fail(Error(error), FailureInfo.REPAY_BEHALF_ACCRUE_INTEREST_FAILED), 0);
                          }
                          // repayBorrowFresh emits repay-borrow-specific logs on errors, so we don't need to
                          return repayBorrowFresh(msg.sender, borrower, repayAmount);
                      }
                      struct RepayBorrowLocalVars {
                          Error err;
                          MathError mathErr;
                          uint repayAmount;
                          uint borrowerIndex;
                          uint accountBorrows;
                          uint accountBorrowsNew;
                          uint totalBorrowsNew;
                          uint actualRepayAmount;
                      }
                      /**
                       * @notice Borrows are repaid by another user (possibly the borrower).
                       * @param payer the account paying off the borrow
                       * @param borrower the account with the debt being payed off
                       * @param repayAmount the amount of undelrying tokens being returned
                       * @return (uint, uint) An error code (0=success, otherwise a failure, see ErrorReporter.sol), and the actual repayment amount.
                       */
                      function repayBorrowFresh(address payer, address borrower, uint repayAmount) internal returns (uint, uint) {
                          /* Fail if repayBorrow not allowed */
                          uint allowed = comptroller.repayBorrowAllowed(address(this), payer, borrower, repayAmount);
                          if (allowed != 0) {
                              return (failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.REPAY_BORROW_COMPTROLLER_REJECTION, allowed), 0);
                          }
                          /* Verify market's block number equals current block number */
                          if (accrualBlockNumber != getBlockNumber()) {
                              return (fail(Error.MARKET_NOT_FRESH, FailureInfo.REPAY_BORROW_FRESHNESS_CHECK), 0);
                          }
                          RepayBorrowLocalVars memory vars;
                          /* We remember the original borrowerIndex for verification purposes */
                          vars.borrowerIndex = accountBorrows[borrower].interestIndex;
                          /* We fetch the amount the borrower owes, with accumulated interest */
                          (vars.mathErr, vars.accountBorrows) = borrowBalanceStoredInternal(borrower);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return (failOpaque(Error.MATH_ERROR, FailureInfo.REPAY_BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED, uint(vars.mathErr)), 0);
                          }
                          /* If repayAmount == -1, repayAmount = accountBorrows */
                          if (repayAmount == uint(-1)) {
                              vars.repayAmount = vars.accountBorrows;
                          } else {
                              vars.repayAmount = repayAmount;
                          }
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                          /*
                           * We call doTransferIn for the payer and the repayAmount
                           *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
                           *  On success, the cToken holds an additional repayAmount of cash.
                           *  doTransferIn reverts if anything goes wrong, since we can't be sure if side effects occurred.
                           *   it returns the amount actually transferred, in case of a fee.
                           */
                          vars.actualRepayAmount = doTransferIn(payer, vars.repayAmount);
                          /*
                           * We calculate the new borrower and total borrow balances, failing on underflow:
                           *  accountBorrowsNew = accountBorrows - actualRepayAmount
                           *  totalBorrowsNew = totalBorrows - actualRepayAmount
                           */
                          (vars.mathErr, vars.accountBorrowsNew) = subUInt(vars.accountBorrows, vars.actualRepayAmount);
                          require(vars.mathErr == MathError.NO_ERROR, "REPAY_BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED");
                          (vars.mathErr, vars.totalBorrowsNew) = subUInt(totalBorrows, vars.actualRepayAmount);
                          require(vars.mathErr == MathError.NO_ERROR, "REPAY_BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED");
                          /* We write the previously calculated values into storage */
                          accountBorrows[borrower].principal = vars.accountBorrowsNew;
                          accountBorrows[borrower].interestIndex = borrowIndex;
                          totalBorrows = vars.totalBorrowsNew;
                          /* We emit a RepayBorrow event */
                          emit RepayBorrow(payer, borrower, vars.actualRepayAmount, vars.accountBorrowsNew, vars.totalBorrowsNew);
                          /* We call the defense hook */
                          // unused function
                          // comptroller.repayBorrowVerify(address(this), payer, borrower, vars.actualRepayAmount, vars.borrowerIndex);
                          return (uint(Error.NO_ERROR), vars.actualRepayAmount);
                      }
                      /**
                       * @notice The sender liquidates the borrowers collateral.
                       *  The collateral seized is transferred to the liquidator.
                       * @param borrower The borrower of this cToken to be liquidated
                       * @param cTokenCollateral The market in which to seize collateral from the borrower
                       * @param repayAmount The amount of the underlying borrowed asset to repay
                       * @return (uint, uint) An error code (0=success, otherwise a failure, see ErrorReporter.sol), and the actual repayment amount.
                       */
                      function liquidateBorrowInternal(address borrower, uint repayAmount, CTokenInterface cTokenCollateral) internal nonReentrant returns (uint, uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted liquidation failed
                              return (fail(Error(error), FailureInfo.LIQUIDATE_ACCRUE_BORROW_INTEREST_FAILED), 0);
                          }
                          error = cTokenCollateral.accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but we still want to log the fact that an attempted liquidation failed
                              return (fail(Error(error), FailureInfo.LIQUIDATE_ACCRUE_COLLATERAL_INTEREST_FAILED), 0);
                          }
                          // liquidateBorrowFresh emits borrow-specific logs on errors, so we don't need to
                          return liquidateBorrowFresh(msg.sender, borrower, repayAmount, cTokenCollateral);
                      }
                      /**
                       * @notice The liquidator liquidates the borrowers collateral.
                       *  The collateral seized is transferred to the liquidator.
                       * @param borrower The borrower of this cToken to be liquidated
                       * @param liquidator The address repaying the borrow and seizing collateral
                       * @param cTokenCollateral The market in which to seize collateral from the borrower
                       * @param repayAmount The amount of the underlying borrowed asset to repay
                       * @return (uint, uint) An error code (0=success, otherwise a failure, see ErrorReporter.sol), and the actual repayment amount.
                       */
                      function liquidateBorrowFresh(address liquidator, address borrower, uint repayAmount, CTokenInterface cTokenCollateral) internal returns (uint, uint) {
                          /* Fail if liquidate not allowed */
                          uint allowed = comptroller.liquidateBorrowAllowed(address(this), address(cTokenCollateral), liquidator, borrower, repayAmount);
                          if (allowed != 0) {
                              return (failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.LIQUIDATE_COMPTROLLER_REJECTION, allowed), 0);
                          }
                          /* Verify market's block number equals current block number */
                          if (accrualBlockNumber != getBlockNumber()) {
                              return (fail(Error.MARKET_NOT_FRESH, FailureInfo.LIQUIDATE_FRESHNESS_CHECK), 0);
                          }
                          /* Verify cTokenCollateral market's block number equals current block number */
                          if (cTokenCollateral.accrualBlockNumber() != getBlockNumber()) {
                              return (fail(Error.MARKET_NOT_FRESH, FailureInfo.LIQUIDATE_COLLATERAL_FRESHNESS_CHECK), 0);
                          }
                          /* Fail if borrower = liquidator */
                          if (borrower == liquidator) {
                              return (fail(Error.INVALID_ACCOUNT_PAIR, FailureInfo.LIQUIDATE_LIQUIDATOR_IS_BORROWER), 0);
                          }
                          /* Fail if repayAmount = 0 */
                          if (repayAmount == 0) {
                              return (fail(Error.INVALID_CLOSE_AMOUNT_REQUESTED, FailureInfo.LIQUIDATE_CLOSE_AMOUNT_IS_ZERO), 0);
                          }
                          /* Fail if repayAmount = -1 */
                          if (repayAmount == uint(-1)) {
                              return (fail(Error.INVALID_CLOSE_AMOUNT_REQUESTED, FailureInfo.LIQUIDATE_CLOSE_AMOUNT_IS_UINT_MAX), 0);
                          }
                          /* Fail if repayBorrow fails */
                          (uint repayBorrowError, uint actualRepayAmount) = repayBorrowFresh(liquidator, borrower, repayAmount);
                          if (repayBorrowError != uint(Error.NO_ERROR)) {
                              return (fail(Error(repayBorrowError), FailureInfo.LIQUIDATE_REPAY_BORROW_FRESH_FAILED), 0);
                          }
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                          /* We calculate the number of collateral tokens that will be seized */
                          (uint amountSeizeError, uint seizeTokens) = comptroller.liquidateCalculateSeizeTokens(address(this), address(cTokenCollateral), actualRepayAmount);
                          require(amountSeizeError == uint(Error.NO_ERROR), "LIQUIDATE_COMPTROLLER_CALCULATE_AMOUNT_SEIZE_FAILED");
                          /* Revert if borrower collateral token balance < seizeTokens */
                          require(cTokenCollateral.balanceOf(borrower) >= seizeTokens, "LIQUIDATE_SEIZE_TOO_MUCH");
                          // If this is also the collateral, run seizeInternal to avoid re-entrancy, otherwise make an external call
                          uint seizeError;
                          if (address(cTokenCollateral) == address(this)) {
                              seizeError = seizeInternal(address(this), liquidator, borrower, seizeTokens);
                          } else {
                              seizeError = cTokenCollateral.seize(liquidator, borrower, seizeTokens);
                          }
                          /* Revert if seize tokens fails (since we cannot be sure of side effects) */
                          require(seizeError == uint(Error.NO_ERROR), "token seizure failed");
                          /* We emit a LiquidateBorrow event */
                          emit LiquidateBorrow(liquidator, borrower, actualRepayAmount, address(cTokenCollateral), seizeTokens);
                          /* We call the defense hook */
                          // unused function
                          // comptroller.liquidateBorrowVerify(address(this), address(cTokenCollateral), liquidator, borrower, actualRepayAmount, seizeTokens);
                          return (uint(Error.NO_ERROR), actualRepayAmount);
                      }
                      /**
                       * @notice Transfers collateral tokens (this market) to the liquidator.
                       * @dev Will fail unless called by another cToken during the process of liquidation.
                       *  Its absolutely critical to use msg.sender as the borrowed cToken and not a parameter.
                       * @param liquidator The account receiving seized collateral
                       * @param borrower The account having collateral seized
                       * @param seizeTokens The number of cTokens to seize
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function seize(address liquidator, address borrower, uint seizeTokens) external nonReentrant returns (uint) {
                          return seizeInternal(msg.sender, liquidator, borrower, seizeTokens);
                      }
                      struct SeizeInternalLocalVars {
                          MathError mathErr;
                          uint borrowerTokensNew;
                          uint liquidatorTokensNew;
                          uint liquidatorSeizeTokens;
                          uint protocolSeizeTokens;
                          uint protocolSeizeAmount;
                          uint exchangeRateMantissa;
                          uint totalReservesNew;
                          uint totalSupplyNew;
                      }
                      /**
                       * @notice Transfers collateral tokens (this market) to the liquidator.
                       * @dev Called only during an in-kind liquidation, or by liquidateBorrow during the liquidation of another CToken.
                       *  Its absolutely critical to use msg.sender as the seizer cToken and not a parameter.
                       * @param seizerToken The contract seizing the collateral (i.e. borrowed cToken)
                       * @param liquidator The account receiving seized collateral
                       * @param borrower The account having collateral seized
                       * @param seizeTokens The number of cTokens to seize
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function seizeInternal(address seizerToken, address liquidator, address borrower, uint seizeTokens) internal returns (uint) {
                          /* Fail if seize not allowed */
                          uint allowed = comptroller.seizeAllowed(address(this), seizerToken, liquidator, borrower, seizeTokens);
                          if (allowed != 0) {
                              return failOpaque(Error.COMPTROLLER_REJECTION, FailureInfo.LIQUIDATE_SEIZE_COMPTROLLER_REJECTION, allowed);
                          }
                          /* Fail if borrower = liquidator */
                          if (borrower == liquidator) {
                              return fail(Error.INVALID_ACCOUNT_PAIR, FailureInfo.LIQUIDATE_SEIZE_LIQUIDATOR_IS_BORROWER);
                          }
                          SeizeInternalLocalVars memory vars;
                          /*
                           * We calculate the new borrower and liquidator token balances, failing on underflow/overflow:
                           *  borrowerTokensNew = accountTokens[borrower] - seizeTokens
                           *  liquidatorTokensNew = accountTokens[liquidator] + seizeTokens
                           */
                          (vars.mathErr, vars.borrowerTokensNew) = subUInt(accountTokens[borrower], seizeTokens);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.LIQUIDATE_SEIZE_BALANCE_DECREMENT_FAILED, uint(vars.mathErr));
                          }
                          vars.protocolSeizeTokens = mul_(seizeTokens, Exp({mantissa: protocolSeizeShareMantissa}));
                          vars.liquidatorSeizeTokens = sub_(seizeTokens, vars.protocolSeizeTokens);
                          (vars.mathErr, vars.exchangeRateMantissa) = exchangeRateStoredInternal();
                          require(vars.mathErr == MathError.NO_ERROR, "exchange rate math error");
                          vars.protocolSeizeAmount = mul_ScalarTruncate(Exp({mantissa: vars.exchangeRateMantissa}), vars.protocolSeizeTokens);
                          vars.totalReservesNew = add_(totalReserves, vars.protocolSeizeAmount);
                          vars.totalSupplyNew = sub_(totalSupply, vars.protocolSeizeTokens);
                          (vars.mathErr, vars.liquidatorTokensNew) = addUInt(accountTokens[liquidator], vars.liquidatorSeizeTokens);
                          if (vars.mathErr != MathError.NO_ERROR) {
                              return failOpaque(Error.MATH_ERROR, FailureInfo.LIQUIDATE_SEIZE_BALANCE_INCREMENT_FAILED, uint(vars.mathErr));
                          }
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                          /* We write the previously calculated values into storage */
                          totalReserves = vars.totalReservesNew;
                          totalSupply = vars.totalSupplyNew;
                          accountTokens[borrower] = vars.borrowerTokensNew;
                          accountTokens[liquidator] = vars.liquidatorTokensNew;
                          /* Emit a Transfer event */
                          emit Transfer(borrower, liquidator, vars.liquidatorSeizeTokens);
                          emit Transfer(borrower, address(this), vars.protocolSeizeTokens);
                          emit ReservesAdded(address(this), vars.protocolSeizeAmount, vars.totalReservesNew);
                          /* We call the defense hook */
                          // unused function
                          // comptroller.seizeVerify(address(this), seizerToken, liquidator, borrower, seizeTokens);
                          return uint(Error.NO_ERROR);
                      }
                      /*** Admin Functions ***/
                      /**
                        * @notice Begins transfer of admin rights. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
                        * @dev Admin function to begin change of admin. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
                        * @param newPendingAdmin New pending admin.
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function _setPendingAdmin(address payable newPendingAdmin) external returns (uint) {
                          // Check caller = admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_PENDING_ADMIN_OWNER_CHECK);
                          }
                          // Save current value, if any, for inclusion in log
                          address oldPendingAdmin = pendingAdmin;
                          // Store pendingAdmin with value newPendingAdmin
                          pendingAdmin = newPendingAdmin;
                          // Emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin)
                          emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                        * @notice Accepts transfer of admin rights. msg.sender must be pendingAdmin
                        * @dev Admin function for pending admin to accept role and update admin
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function _acceptAdmin() external returns (uint) {
                          // Check caller is pendingAdmin and pendingAdmin ≠ address(0)
                          if (msg.sender != pendingAdmin || msg.sender == address(0)) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.ACCEPT_ADMIN_PENDING_ADMIN_CHECK);
                          }
                          // Save current values for inclusion in log
                          address oldAdmin = admin;
                          address oldPendingAdmin = pendingAdmin;
                          // Store admin with value pendingAdmin
                          admin = pendingAdmin;
                          // Clear the pending value
                          pendingAdmin = address(0);
                          emit NewAdmin(oldAdmin, admin);
                          emit NewPendingAdmin(oldPendingAdmin, pendingAdmin);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                        * @notice Sets a new comptroller for the market
                        * @dev Admin function to set a new comptroller
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function _setComptroller(ComptrollerInterface newComptroller) public returns (uint) {
                          // Check caller is admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_COMPTROLLER_OWNER_CHECK);
                          }
                          ComptrollerInterface oldComptroller = comptroller;
                          // Ensure invoke comptroller.isComptroller() returns true
                          require(newComptroller.isComptroller(), "marker method returned false");
                          // Set market's comptroller to newComptroller
                          comptroller = newComptroller;
                          // Emit NewComptroller(oldComptroller, newComptroller)
                          emit NewComptroller(oldComptroller, newComptroller);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                        * @notice accrues interest and sets a new reserve factor for the protocol using _setReserveFactorFresh
                        * @dev Admin function to accrue interest and set a new reserve factor
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function _setReserveFactor(uint newReserveFactorMantissa) external nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted reserve factor change failed.
                              return fail(Error(error), FailureInfo.SET_RESERVE_FACTOR_ACCRUE_INTEREST_FAILED);
                          }
                          // _setReserveFactorFresh emits reserve-factor-specific logs on errors, so we don't need to.
                          return _setReserveFactorFresh(newReserveFactorMantissa);
                      }
                      /**
                        * @notice Sets a new reserve factor for the protocol (*requires fresh interest accrual)
                        * @dev Admin function to set a new reserve factor
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function _setReserveFactorFresh(uint newReserveFactorMantissa) internal returns (uint) {
                          // Check caller is admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_RESERVE_FACTOR_ADMIN_CHECK);
                          }
                          // Verify market's block number equals current block number
                          if (accrualBlockNumber != getBlockNumber()) {
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.SET_RESERVE_FACTOR_FRESH_CHECK);
                          }
                          // Check newReserveFactor ≤ maxReserveFactor
                          if (newReserveFactorMantissa > reserveFactorMaxMantissa) {
                              return fail(Error.BAD_INPUT, FailureInfo.SET_RESERVE_FACTOR_BOUNDS_CHECK);
                          }
                          uint oldReserveFactorMantissa = reserveFactorMantissa;
                          reserveFactorMantissa = newReserveFactorMantissa;
                          emit NewReserveFactor(oldReserveFactorMantissa, newReserveFactorMantissa);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                       * @notice Accrues interest and reduces reserves by transferring from msg.sender
                       * @param addAmount Amount of addition to reserves
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function _addReservesInternal(uint addAmount) internal nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted reduce reserves failed.
                              return fail(Error(error), FailureInfo.ADD_RESERVES_ACCRUE_INTEREST_FAILED);
                          }
                          // _addReservesFresh emits reserve-addition-specific logs on errors, so we don't need to.
                          (error, ) = _addReservesFresh(addAmount);
                          return error;
                      }
                      /**
                       * @notice Add reserves by transferring from caller
                       * @dev Requires fresh interest accrual
                       * @param addAmount Amount of addition to reserves
                       * @return (uint, uint) An error code (0=success, otherwise a failure (see ErrorReporter.sol for details)) and the actual amount added, net token fees
                       */
                      function _addReservesFresh(uint addAmount) internal returns (uint, uint) {
                          // totalReserves + actualAddAmount
                          uint totalReservesNew;
                          uint actualAddAmount;
                          // We fail gracefully unless market's block number equals current block number
                          if (accrualBlockNumber != getBlockNumber()) {
                              return (fail(Error.MARKET_NOT_FRESH, FailureInfo.ADD_RESERVES_FRESH_CHECK), actualAddAmount);
                          }
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                          /*
                           * We call doTransferIn for the caller and the addAmount
                           *  Note: The cToken must handle variations between ERC-20 and ETH underlying.
                           *  On success, the cToken holds an additional addAmount of cash.
                           *  doTransferIn reverts if anything goes wrong, since we can't be sure if side effects occurred.
                           *  it returns the amount actually transferred, in case of a fee.
                           */
                          actualAddAmount = doTransferIn(msg.sender, addAmount);
                          totalReservesNew = totalReserves + actualAddAmount;
                          /* Revert on overflow */
                          require(totalReservesNew >= totalReserves, "add reserves unexpected overflow");
                          // Store reserves[n+1] = reserves[n] + actualAddAmount
                          totalReserves = totalReservesNew;
                          /* Emit NewReserves(admin, actualAddAmount, reserves[n+1]) */
                          emit ReservesAdded(msg.sender, actualAddAmount, totalReservesNew);
                          /* Return (NO_ERROR, actualAddAmount) */
                          return (uint(Error.NO_ERROR), actualAddAmount);
                      }
                      /**
                       * @notice Accrues interest and reduces reserves by transferring to admin
                       * @param reduceAmount Amount of reduction to reserves
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function _reduceReserves(uint reduceAmount) external nonReentrant returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted reduce reserves failed.
                              return fail(Error(error), FailureInfo.REDUCE_RESERVES_ACCRUE_INTEREST_FAILED);
                          }
                          // _reduceReservesFresh emits reserve-reduction-specific logs on errors, so we don't need to.
                          return _reduceReservesFresh(reduceAmount);
                      }
                      /**
                       * @notice Reduces reserves by transferring to admin
                       * @dev Requires fresh interest accrual
                       * @param reduceAmount Amount of reduction to reserves
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function _reduceReservesFresh(uint reduceAmount) internal returns (uint) {
                          // totalReserves - reduceAmount
                          uint totalReservesNew;
                          // Check caller is admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.REDUCE_RESERVES_ADMIN_CHECK);
                          }
                          // We fail gracefully unless market's block number equals current block number
                          if (accrualBlockNumber != getBlockNumber()) {
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.REDUCE_RESERVES_FRESH_CHECK);
                          }
                          // Fail gracefully if protocol has insufficient underlying cash
                          if (getCashPrior() < reduceAmount) {
                              return fail(Error.TOKEN_INSUFFICIENT_CASH, FailureInfo.REDUCE_RESERVES_CASH_NOT_AVAILABLE);
                          }
                          // Check reduceAmount ≤ reserves[n] (totalReserves)
                          if (reduceAmount > totalReserves) {
                              return fail(Error.BAD_INPUT, FailureInfo.REDUCE_RESERVES_VALIDATION);
                          }
                          /////////////////////////
                          // EFFECTS & INTERACTIONS
                          // (No safe failures beyond this point)
                          totalReservesNew = totalReserves - reduceAmount;
                          // We checked reduceAmount <= totalReserves above, so this should never revert.
                          require(totalReservesNew <= totalReserves, "reduce reserves unexpected underflow");
                          // Store reserves[n+1] = reserves[n] - reduceAmount
                          totalReserves = totalReservesNew;
                          // doTransferOut reverts if anything goes wrong, since we can't be sure if side effects occurred.
                          doTransferOut(admin, reduceAmount);
                          emit ReservesReduced(admin, reduceAmount, totalReservesNew);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                       * @notice accrues interest and updates the interest rate model using _setInterestRateModelFresh
                       * @dev Admin function to accrue interest and update the interest rate model
                       * @param newInterestRateModel the new interest rate model to use
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function _setInterestRateModel(InterestRateModel newInterestRateModel) public returns (uint) {
                          uint error = accrueInterest();
                          if (error != uint(Error.NO_ERROR)) {
                              // accrueInterest emits logs on errors, but on top of that we want to log the fact that an attempted change of interest rate model failed
                              return fail(Error(error), FailureInfo.SET_INTEREST_RATE_MODEL_ACCRUE_INTEREST_FAILED);
                          }
                          // _setInterestRateModelFresh emits interest-rate-model-update-specific logs on errors, so we don't need to.
                          return _setInterestRateModelFresh(newInterestRateModel);
                      }
                      /**
                       * @notice updates the interest rate model (*requires fresh interest accrual)
                       * @dev Admin function to update the interest rate model
                       * @param newInterestRateModel the new interest rate model to use
                       * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                       */
                      function _setInterestRateModelFresh(InterestRateModel newInterestRateModel) internal returns (uint) {
                          // Used to store old model for use in the event that is emitted on success
                          InterestRateModel oldInterestRateModel;
                          // Check caller is admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_INTEREST_RATE_MODEL_OWNER_CHECK);
                          }
                          // We fail gracefully unless market's block number equals current block number
                          if (accrualBlockNumber != getBlockNumber()) {
                              return fail(Error.MARKET_NOT_FRESH, FailureInfo.SET_INTEREST_RATE_MODEL_FRESH_CHECK);
                          }
                          // Track the market's current interest rate model
                          oldInterestRateModel = interestRateModel;
                          // Ensure invoke newInterestRateModel.isInterestRateModel() returns true
                          require(newInterestRateModel.isInterestRateModel(), "marker method returned false");
                          // Set the interest rate model to newInterestRateModel
                          interestRateModel = newInterestRateModel;
                          // Emit NewMarketInterestRateModel(oldInterestRateModel, newInterestRateModel)
                          emit NewMarketInterestRateModel(oldInterestRateModel, newInterestRateModel);
                          return uint(Error.NO_ERROR);
                      }
                      /*** Safe Token ***/
                      /**
                       * @notice Gets balance of this contract in terms of the underlying
                       * @dev This excludes the value of the current message, if any
                       * @return The quantity of underlying owned by this contract
                       */
                      function getCashPrior() internal view returns (uint);
                      /**
                       * @dev Performs a transfer in, reverting upon failure. Returns the amount actually transferred to the protocol, in case of a fee.
                       *  This may revert due to insufficient balance or insufficient allowance.
                       */
                      function doTransferIn(address from, uint amount) internal returns (uint);
                      /**
                       * @dev Performs a transfer out, ideally returning an explanatory error code upon failure tather than reverting.
                       *  If caller has not called checked protocol's balance, may revert due to insufficient cash held in the contract.
                       *  If caller has checked protocol's balance, and verified it is >= amount, this should not revert in normal conditions.
                       */
                      function doTransferOut(address payable to, uint amount) internal;
                      /*** Reentrancy Guard ***/
                      /**
                       * @dev Prevents a contract from calling itself, directly or indirectly.
                       */
                      modifier nonReentrant() {
                          require(_notEntered, "re-entered");
                          _notEntered = false;
                          _;
                          _notEntered = true; // get a gas-refund post-Istanbul
                      }
                  }
                  pragma solidity ^0.5.16;
                  import "./ComptrollerInterface.sol";
                  import "./InterestRateModel.sol";
                  import "./EIP20NonStandardInterface.sol";
                  contract CTokenStorage {
                      /**
                       * @dev Guard variable for re-entrancy checks
                       */
                      bool internal _notEntered;
                      /**
                       * @notice EIP-20 token name for this token
                       */
                      string public name;
                      /**
                       * @notice EIP-20 token symbol for this token
                       */
                      string public symbol;
                      /**
                       * @notice EIP-20 token decimals for this token
                       */
                      uint8 public decimals;
                      /**
                       * @notice Maximum borrow rate that can ever be applied (.0005% / block)
                       */
                      uint internal constant borrowRateMaxMantissa = 0.0005e16;
                      /**
                       * @notice Maximum fraction of interest that can be set aside for reserves
                       */
                      uint internal constant reserveFactorMaxMantissa = 1e18;
                      /**
                       * @notice Administrator for this contract
                       */
                      address payable public admin;
                      /**
                       * @notice Pending administrator for this contract
                       */
                      address payable public pendingAdmin;
                      /**
                       * @notice Contract which oversees inter-cToken operations
                       */
                      ComptrollerInterface public comptroller;
                      /**
                       * @notice Model which tells what the current interest rate should be
                       */
                      InterestRateModel public interestRateModel;
                      /**
                       * @notice Initial exchange rate used when minting the first CTokens (used when totalSupply = 0)
                       */
                      uint internal initialExchangeRateMantissa;
                      /**
                       * @notice Fraction of interest currently set aside for reserves
                       */
                      uint public reserveFactorMantissa;
                      /**
                       * @notice Block number that interest was last accrued at
                       */
                      uint public accrualBlockNumber;
                      /**
                       * @notice Accumulator of the total earned interest rate since the opening of the market
                       */
                      uint public borrowIndex;
                      /**
                       * @notice Total amount of outstanding borrows of the underlying in this market
                       */
                      uint public totalBorrows;
                      /**
                       * @notice Total amount of reserves of the underlying held in this market
                       */
                      uint public totalReserves;
                      /**
                       * @notice Total number of tokens in circulation
                       */
                      uint public totalSupply;
                      /**
                       * @notice Official record of token balances for each account
                       */
                      mapping (address => uint) internal accountTokens;
                      /**
                       * @notice Approved token transfer amounts on behalf of others
                       */
                      mapping (address => mapping (address => uint)) internal transferAllowances;
                      /**
                       * @notice Container for borrow balance information
                       * @member principal Total balance (with accrued interest), after applying the most recent balance-changing action
                       * @member interestIndex Global borrowIndex as of the most recent balance-changing action
                       */
                      struct BorrowSnapshot {
                          uint principal;
                          uint interestIndex;
                      }
                      /**
                       * @notice Mapping of account addresses to outstanding borrow balances
                       */
                      mapping(address => BorrowSnapshot) internal accountBorrows;
                      /**
                       * @notice Share of seized collateral that is added to reserves
                       */
                      uint public constant protocolSeizeShareMantissa = 2.8e16; //2.8%
                  }
                  contract CTokenInterface is CTokenStorage {
                      /**
                       * @notice Indicator that this is a CToken contract (for inspection)
                       */
                      bool public constant isCToken = true;
                      /*** Market Events ***/
                      /**
                       * @notice Event emitted when interest is accrued
                       */
                      event AccrueInterest(uint cashPrior, uint interestAccumulated, uint borrowIndex, uint totalBorrows);
                      /**
                       * @notice Event emitted when tokens are minted
                       */
                      event Mint(address minter, uint mintAmount, uint mintTokens);
                      /**
                       * @notice Event emitted when tokens are redeemed
                       */
                      event Redeem(address redeemer, uint redeemAmount, uint redeemTokens);
                      /**
                       * @notice Event emitted when underlying is borrowed
                       */
                      event Borrow(address borrower, uint borrowAmount, uint accountBorrows, uint totalBorrows);
                      /**
                       * @notice Event emitted when a borrow is repaid
                       */
                      event RepayBorrow(address payer, address borrower, uint repayAmount, uint accountBorrows, uint totalBorrows);
                      /**
                       * @notice Event emitted when a borrow is liquidated
                       */
                      event LiquidateBorrow(address liquidator, address borrower, uint repayAmount, address cTokenCollateral, uint seizeTokens);
                      /*** Admin Events ***/
                      /**
                       * @notice Event emitted when pendingAdmin is changed
                       */
                      event NewPendingAdmin(address oldPendingAdmin, address newPendingAdmin);
                      /**
                       * @notice Event emitted when pendingAdmin is accepted, which means admin is updated
                       */
                      event NewAdmin(address oldAdmin, address newAdmin);
                      /**
                       * @notice Event emitted when comptroller is changed
                       */
                      event NewComptroller(ComptrollerInterface oldComptroller, ComptrollerInterface newComptroller);
                      /**
                       * @notice Event emitted when interestRateModel is changed
                       */
                      event NewMarketInterestRateModel(InterestRateModel oldInterestRateModel, InterestRateModel newInterestRateModel);
                      /**
                       * @notice Event emitted when the reserve factor is changed
                       */
                      event NewReserveFactor(uint oldReserveFactorMantissa, uint newReserveFactorMantissa);
                      /**
                       * @notice Event emitted when the reserves are added
                       */
                      event ReservesAdded(address benefactor, uint addAmount, uint newTotalReserves);
                      /**
                       * @notice Event emitted when the reserves are reduced
                       */
                      event ReservesReduced(address admin, uint reduceAmount, uint newTotalReserves);
                      /**
                       * @notice EIP20 Transfer event
                       */
                      event Transfer(address indexed from, address indexed to, uint amount);
                      /**
                       * @notice EIP20 Approval event
                       */
                      event Approval(address indexed owner, address indexed spender, uint amount);
                      /**
                       * @notice Failure event
                       */
                      event Failure(uint error, uint info, uint detail);
                      /*** User Interface ***/
                      function transfer(address dst, uint amount) external returns (bool);
                      function transferFrom(address src, address dst, uint amount) external returns (bool);
                      function approve(address spender, uint amount) external returns (bool);
                      function allowance(address owner, address spender) external view returns (uint);
                      function balanceOf(address owner) external view returns (uint);
                      function balanceOfUnderlying(address owner) external returns (uint);
                      function getAccountSnapshot(address account) external view returns (uint, uint, uint, uint);
                      function borrowRatePerBlock() external view returns (uint);
                      function supplyRatePerBlock() external view returns (uint);
                      function totalBorrowsCurrent() external returns (uint);
                      function borrowBalanceCurrent(address account) external returns (uint);
                      function borrowBalanceStored(address account) public view returns (uint);
                      function exchangeRateCurrent() public returns (uint);
                      function exchangeRateStored() public view returns (uint);
                      function getCash() external view returns (uint);
                      function accrueInterest() public returns (uint);
                      function seize(address liquidator, address borrower, uint seizeTokens) external returns (uint);
                      /*** Admin Functions ***/
                      function _setPendingAdmin(address payable newPendingAdmin) external returns (uint);
                      function _acceptAdmin() external returns (uint);
                      function _setComptroller(ComptrollerInterface newComptroller) public returns (uint);
                      function _setReserveFactor(uint newReserveFactorMantissa) external returns (uint);
                      function _reduceReserves(uint reduceAmount) external returns (uint);
                      function _setInterestRateModel(InterestRateModel newInterestRateModel) public returns (uint);
                  }
                  contract CErc20Storage {
                      /**
                       * @notice Underlying asset for this CToken
                       */
                      address public underlying;
                  }
                  contract CErc20Interface is CErc20Storage {
                      /*** User Interface ***/
                      function mint(uint mintAmount) external returns (uint);
                      function redeem(uint redeemTokens) external returns (uint);
                      function redeemUnderlying(uint redeemAmount) external returns (uint);
                      function borrow(uint borrowAmount) external returns (uint);
                      function repayBorrow(uint repayAmount) external returns (uint);
                      function repayBorrowBehalf(address borrower, uint repayAmount) external returns (uint);
                      function liquidateBorrow(address borrower, uint repayAmount, CTokenInterface cTokenCollateral) external returns (uint);
                      function sweepToken(EIP20NonStandardInterface token) external;
                      /*** Admin Functions ***/
                      function _addReserves(uint addAmount) external returns (uint);
                  }
                  contract CDelegationStorage {
                      /**
                       * @notice Implementation address for this contract
                       */
                      address public implementation;
                  }
                  contract CDelegatorInterface is CDelegationStorage {
                      /**
                       * @notice Emitted when implementation is changed
                       */
                      event NewImplementation(address oldImplementation, address newImplementation);
                      /**
                       * @notice Called by the admin to update the implementation of the delegator
                       * @param implementation_ The address of the new implementation for delegation
                       * @param allowResign Flag to indicate whether to call _resignImplementation on the old implementation
                       * @param becomeImplementationData The encoded bytes data to be passed to _becomeImplementation
                       */
                      function _setImplementation(address implementation_, bool allowResign, bytes memory becomeImplementationData) public;
                  }
                  contract CDelegateInterface is CDelegationStorage {
                      /**
                       * @notice Called by the delegator on a delegate to initialize it for duty
                       * @dev Should revert if any issues arise which make it unfit for delegation
                       * @param data The encoded bytes data for any initialization
                       */
                      function _becomeImplementation(bytes memory data) public;
                      /**
                       * @notice Called by the delegator on a delegate to forfeit its responsibility
                       */
                      function _resignImplementation() public;
                  }
                  pragma solidity ^0.5.16;
                  /**
                    * @title Careful Math
                    * @author Compound
                    * @notice Derived from OpenZeppelin's SafeMath library
                    *         https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/math/SafeMath.sol
                    */
                  contract CarefulMath {
                      /**
                       * @dev Possible error codes that we can return
                       */
                      enum MathError {
                          NO_ERROR,
                          DIVISION_BY_ZERO,
                          INTEGER_OVERFLOW,
                          INTEGER_UNDERFLOW
                      }
                      /**
                      * @dev Multiplies two numbers, returns an error on overflow.
                      */
                      function mulUInt(uint a, uint b) internal pure returns (MathError, uint) {
                          if (a == 0) {
                              return (MathError.NO_ERROR, 0);
                          }
                          uint c = a * b;
                          if (c / a != b) {
                              return (MathError.INTEGER_OVERFLOW, 0);
                          } else {
                              return (MathError.NO_ERROR, c);
                          }
                      }
                      /**
                      * @dev Integer division of two numbers, truncating the quotient.
                      */
                      function divUInt(uint a, uint b) internal pure returns (MathError, uint) {
                          if (b == 0) {
                              return (MathError.DIVISION_BY_ZERO, 0);
                          }
                          return (MathError.NO_ERROR, a / b);
                      }
                      /**
                      * @dev Subtracts two numbers, returns an error on overflow (i.e. if subtrahend is greater than minuend).
                      */
                      function subUInt(uint a, uint b) internal pure returns (MathError, uint) {
                          if (b <= a) {
                              return (MathError.NO_ERROR, a - b);
                          } else {
                              return (MathError.INTEGER_UNDERFLOW, 0);
                          }
                      }
                      /**
                      * @dev Adds two numbers, returns an error on overflow.
                      */
                      function addUInt(uint a, uint b) internal pure returns (MathError, uint) {
                          uint c = a + b;
                          if (c >= a) {
                              return (MathError.NO_ERROR, c);
                          } else {
                              return (MathError.INTEGER_OVERFLOW, 0);
                          }
                      }
                      /**
                      * @dev add a and b and then subtract c
                      */
                      function addThenSubUInt(uint a, uint b, uint c) internal pure returns (MathError, uint) {
                          (MathError err0, uint sum) = addUInt(a, b);
                          if (err0 != MathError.NO_ERROR) {
                              return (err0, 0);
                          }
                          return subUInt(sum, c);
                      }
                  }pragma solidity ^0.5.16;
                  import "./CToken.sol";
                  import "./ErrorReporter.sol";
                  import "./PriceOracle.sol";
                  import "./ComptrollerInterface.sol";
                  import "./ComptrollerStorage.sol";
                  import "./Unitroller.sol";
                  import "./Governance/Comp.sol";
                  /**
                   * @title Compound's Comptroller Contract
                   * @author Compound
                   */
                  contract Comptroller is ComptrollerV7Storage, ComptrollerInterface, ComptrollerErrorReporter, ExponentialNoError {
                      /// @notice Emitted when an admin supports a market
                      event MarketListed(CToken cToken);
                      /// @notice Emitted when an account enters a market
                      event MarketEntered(CToken cToken, address account);
                      /// @notice Emitted when an account exits a market
                      event MarketExited(CToken cToken, address account);
                      /// @notice Emitted when close factor is changed by admin
                      event NewCloseFactor(uint oldCloseFactorMantissa, uint newCloseFactorMantissa);
                      /// @notice Emitted when a collateral factor is changed by admin
                      event NewCollateralFactor(CToken cToken, uint oldCollateralFactorMantissa, uint newCollateralFactorMantissa);
                      /// @notice Emitted when liquidation incentive is changed by admin
                      event NewLiquidationIncentive(uint oldLiquidationIncentiveMantissa, uint newLiquidationIncentiveMantissa);
                      /// @notice Emitted when price oracle is changed
                      event NewPriceOracle(PriceOracle oldPriceOracle, PriceOracle newPriceOracle);
                      /// @notice Emitted when pause guardian is changed
                      event NewPauseGuardian(address oldPauseGuardian, address newPauseGuardian);
                      /// @notice Emitted when an action is paused globally
                      event ActionPaused(string action, bool pauseState);
                      /// @notice Emitted when an action is paused on a market
                      event ActionPaused(CToken cToken, string action, bool pauseState);
                      /// @notice Emitted when a new borrow-side COMP speed is calculated for a market
                      event CompBorrowSpeedUpdated(CToken indexed cToken, uint newSpeed);
                      /// @notice Emitted when a new supply-side COMP speed is calculated for a market
                      event CompSupplySpeedUpdated(CToken indexed cToken, uint newSpeed);
                      /// @notice Emitted when a new COMP speed is set for a contributor
                      event ContributorCompSpeedUpdated(address indexed contributor, uint newSpeed);
                      /// @notice Emitted when COMP is distributed to a supplier
                      event DistributedSupplierComp(CToken indexed cToken, address indexed supplier, uint compDelta, uint compSupplyIndex);
                      /// @notice Emitted when COMP is distributed to a borrower
                      event DistributedBorrowerComp(CToken indexed cToken, address indexed borrower, uint compDelta, uint compBorrowIndex);
                      /// @notice Emitted when borrow cap for a cToken is changed
                      event NewBorrowCap(CToken indexed cToken, uint newBorrowCap);
                      /// @notice Emitted when borrow cap guardian is changed
                      event NewBorrowCapGuardian(address oldBorrowCapGuardian, address newBorrowCapGuardian);
                      /// @notice Emitted when COMP is granted by admin
                      event CompGranted(address recipient, uint amount);
                      /// @notice Emitted when COMP accrued for a user has been manually adjusted.
                      event CompAccruedAdjusted(address indexed user, uint oldCompAccrued, uint newCompAccrued);
                      /// @notice Emitted when COMP receivable for a user has been updated.
                      event CompReceivableUpdated(address indexed user, uint oldCompReceivable, uint newCompReceivable);
                      /// @notice The initial COMP index for a market
                      uint224 public constant compInitialIndex = 1e36;
                      // closeFactorMantissa must be strictly greater than this value
                      uint internal constant closeFactorMinMantissa = 0.05e18; // 0.05
                      // closeFactorMantissa must not exceed this value
                      uint internal constant closeFactorMaxMantissa = 0.9e18; // 0.9
                      // No collateralFactorMantissa may exceed this value
                      uint internal constant collateralFactorMaxMantissa = 0.9e18; // 0.9
                      constructor() public {
                          admin = msg.sender;
                      }
                      /*** Assets You Are In ***/
                      /**
                       * @notice Returns the assets an account has entered
                       * @param account The address of the account to pull assets for
                       * @return A dynamic list with the assets the account has entered
                       */
                      function getAssetsIn(address account) external view returns (CToken[] memory) {
                          CToken[] memory assetsIn = accountAssets[account];
                          return assetsIn;
                      }
                      /**
                       * @notice Returns whether the given account is entered in the given asset
                       * @param account The address of the account to check
                       * @param cToken The cToken to check
                       * @return True if the account is in the asset, otherwise false.
                       */
                      function checkMembership(address account, CToken cToken) external view returns (bool) {
                          return markets[address(cToken)].accountMembership[account];
                      }
                      /**
                       * @notice Add assets to be included in account liquidity calculation
                       * @param cTokens The list of addresses of the cToken markets to be enabled
                       * @return Success indicator for whether each corresponding market was entered
                       */
                      function enterMarkets(address[] memory cTokens) public returns (uint[] memory) {
                          uint len = cTokens.length;
                          uint[] memory results = new uint[](len);
                          for (uint i = 0; i < len; i++) {
                              CToken cToken = CToken(cTokens[i]);
                              results[i] = uint(addToMarketInternal(cToken, msg.sender));
                          }
                          return results;
                      }
                      /**
                       * @notice Add the market to the borrower's "assets in" for liquidity calculations
                       * @param cToken The market to enter
                       * @param borrower The address of the account to modify
                       * @return Success indicator for whether the market was entered
                       */
                      function addToMarketInternal(CToken cToken, address borrower) internal returns (Error) {
                          Market storage marketToJoin = markets[address(cToken)];
                          if (!marketToJoin.isListed) {
                              // market is not listed, cannot join
                              return Error.MARKET_NOT_LISTED;
                          }
                          if (marketToJoin.accountMembership[borrower] == true) {
                              // already joined
                              return Error.NO_ERROR;
                          }
                          // survived the gauntlet, add to list
                          // NOTE: we store these somewhat redundantly as a significant optimization
                          //  this avoids having to iterate through the list for the most common use cases
                          //  that is, only when we need to perform liquidity checks
                          //  and not whenever we want to check if an account is in a particular market
                          marketToJoin.accountMembership[borrower] = true;
                          accountAssets[borrower].push(cToken);
                          emit MarketEntered(cToken, borrower);
                          return Error.NO_ERROR;
                      }
                      /**
                       * @notice Removes asset from sender's account liquidity calculation
                       * @dev Sender must not have an outstanding borrow balance in the asset,
                       *  or be providing necessary collateral for an outstanding borrow.
                       * @param cTokenAddress The address of the asset to be removed
                       * @return Whether or not the account successfully exited the market
                       */
                      function exitMarket(address cTokenAddress) external returns (uint) {
                          CToken cToken = CToken(cTokenAddress);
                          /* Get sender tokensHeld and amountOwed underlying from the cToken */
                          (uint oErr, uint tokensHeld, uint amountOwed, ) = cToken.getAccountSnapshot(msg.sender);
                          require(oErr == 0, "exitMarket: getAccountSnapshot failed"); // semi-opaque error code
                          /* Fail if the sender has a borrow balance */
                          if (amountOwed != 0) {
                              return fail(Error.NONZERO_BORROW_BALANCE, FailureInfo.EXIT_MARKET_BALANCE_OWED);
                          }
                          /* Fail if the sender is not permitted to redeem all of their tokens */
                          uint allowed = redeemAllowedInternal(cTokenAddress, msg.sender, tokensHeld);
                          if (allowed != 0) {
                              return failOpaque(Error.REJECTION, FailureInfo.EXIT_MARKET_REJECTION, allowed);
                          }
                          Market storage marketToExit = markets[address(cToken)];
                          /* Return true if the sender is not already ‘in’ the market */
                          if (!marketToExit.accountMembership[msg.sender]) {
                              return uint(Error.NO_ERROR);
                          }
                          /* Set cToken account membership to false */
                          delete marketToExit.accountMembership[msg.sender];
                          /* Delete cToken from the account’s list of assets */
                          // load into memory for faster iteration
                          CToken[] memory userAssetList = accountAssets[msg.sender];
                          uint len = userAssetList.length;
                          uint assetIndex = len;
                          for (uint i = 0; i < len; i++) {
                              if (userAssetList[i] == cToken) {
                                  assetIndex = i;
                                  break;
                              }
                          }
                          // We *must* have found the asset in the list or our redundant data structure is broken
                          assert(assetIndex < len);
                          // copy last item in list to location of item to be removed, reduce length by 1
                          CToken[] storage storedList = accountAssets[msg.sender];
                          storedList[assetIndex] = storedList[storedList.length - 1];
                          storedList.length--;
                          emit MarketExited(cToken, msg.sender);
                          return uint(Error.NO_ERROR);
                      }
                      /*** Policy Hooks ***/
                      /**
                       * @notice Checks if the account should be allowed to mint tokens in the given market
                       * @param cToken The market to verify the mint against
                       * @param minter The account which would get the minted tokens
                       * @param mintAmount The amount of underlying being supplied to the market in exchange for tokens
                       * @return 0 if the mint is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)
                       */
                      function mintAllowed(address cToken, address minter, uint mintAmount) external returns (uint) {
                          // Pausing is a very serious situation - we revert to sound the alarms
                          require(!mintGuardianPaused[cToken], "mint is paused");
                          // Shh - currently unused
                          minter;
                          mintAmount;
                          if (!markets[cToken].isListed) {
                              return uint(Error.MARKET_NOT_LISTED);
                          }
                          // Keep the flywheel moving
                          updateCompSupplyIndex(cToken);
                          distributeSupplierComp(cToken, minter);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                       * @notice Validates mint and reverts on rejection. May emit logs.
                       * @param cToken Asset being minted
                       * @param minter The address minting the tokens
                       * @param actualMintAmount The amount of the underlying asset being minted
                       * @param mintTokens The number of tokens being minted
                       */
                      function mintVerify(address cToken, address minter, uint actualMintAmount, uint mintTokens) external {
                          // Shh - currently unused
                          cToken;
                          minter;
                          actualMintAmount;
                          mintTokens;
                          // Shh - we don't ever want this hook to be marked pure
                          if (false) {
                              maxAssets = maxAssets;
                          }
                      }
                      /**
                       * @notice Checks if the account should be allowed to redeem tokens in the given market
                       * @param cToken The market to verify the redeem against
                       * @param redeemer The account which would redeem the tokens
                       * @param redeemTokens The number of cTokens to exchange for the underlying asset in the market
                       * @return 0 if the redeem is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)
                       */
                      function redeemAllowed(address cToken, address redeemer, uint redeemTokens) external returns (uint) {
                          uint allowed = redeemAllowedInternal(cToken, redeemer, redeemTokens);
                          if (allowed != uint(Error.NO_ERROR)) {
                              return allowed;
                          }
                          // Keep the flywheel moving
                          updateCompSupplyIndex(cToken);
                          distributeSupplierComp(cToken, redeemer);
                          return uint(Error.NO_ERROR);
                      }
                      function redeemAllowedInternal(address cToken, address redeemer, uint redeemTokens) internal view returns (uint) {
                          if (!markets[cToken].isListed) {
                              return uint(Error.MARKET_NOT_LISTED);
                          }
                          /* If the redeemer is not 'in' the market, then we can bypass the liquidity check */
                          if (!markets[cToken].accountMembership[redeemer]) {
                              return uint(Error.NO_ERROR);
                          }
                          /* Otherwise, perform a hypothetical liquidity check to guard against shortfall */
                          (Error err, , uint shortfall) = getHypotheticalAccountLiquidityInternal(redeemer, CToken(cToken), redeemTokens, 0);
                          if (err != Error.NO_ERROR) {
                              return uint(err);
                          }
                          if (shortfall > 0) {
                              return uint(Error.INSUFFICIENT_LIQUIDITY);
                          }
                          return uint(Error.NO_ERROR);
                      }
                      /**
                       * @notice Validates redeem and reverts on rejection. May emit logs.
                       * @param cToken Asset being redeemed
                       * @param redeemer The address redeeming the tokens
                       * @param redeemAmount The amount of the underlying asset being redeemed
                       * @param redeemTokens The number of tokens being redeemed
                       */
                      function redeemVerify(address cToken, address redeemer, uint redeemAmount, uint redeemTokens) external {
                          // Shh - currently unused
                          cToken;
                          redeemer;
                          // Require tokens is zero or amount is also zero
                          if (redeemTokens == 0 && redeemAmount > 0) {
                              revert("redeemTokens zero");
                          }
                      }
                      /**
                       * @notice Checks if the account should be allowed to borrow the underlying asset of the given market
                       * @param cToken The market to verify the borrow against
                       * @param borrower The account which would borrow the asset
                       * @param borrowAmount The amount of underlying the account would borrow
                       * @return 0 if the borrow is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)
                       */
                      function borrowAllowed(address cToken, address borrower, uint borrowAmount) external returns (uint) {
                          // Pausing is a very serious situation - we revert to sound the alarms
                          require(!borrowGuardianPaused[cToken], "borrow is paused");
                          if (!markets[cToken].isListed) {
                              return uint(Error.MARKET_NOT_LISTED);
                          }
                          if (!markets[cToken].accountMembership[borrower]) {
                              // only cTokens may call borrowAllowed if borrower not in market
                              require(msg.sender == cToken, "sender must be cToken");
                              // attempt to add borrower to the market
                              Error err = addToMarketInternal(CToken(msg.sender), borrower);
                              if (err != Error.NO_ERROR) {
                                  return uint(err);
                              }
                              // it should be impossible to break the important invariant
                              assert(markets[cToken].accountMembership[borrower]);
                          }
                          if (oracle.getUnderlyingPrice(CToken(cToken)) == 0) {
                              return uint(Error.PRICE_ERROR);
                          }
                          uint borrowCap = borrowCaps[cToken];
                          // Borrow cap of 0 corresponds to unlimited borrowing
                          if (borrowCap != 0) {
                              uint totalBorrows = CToken(cToken).totalBorrows();
                              uint nextTotalBorrows = add_(totalBorrows, borrowAmount);
                              require(nextTotalBorrows < borrowCap, "market borrow cap reached");
                          }
                          (Error err, , uint shortfall) = getHypotheticalAccountLiquidityInternal(borrower, CToken(cToken), 0, borrowAmount);
                          if (err != Error.NO_ERROR) {
                              return uint(err);
                          }
                          if (shortfall > 0) {
                              return uint(Error.INSUFFICIENT_LIQUIDITY);
                          }
                          // Keep the flywheel moving
                          Exp memory borrowIndex = Exp({mantissa: CToken(cToken).borrowIndex()});
                          updateCompBorrowIndex(cToken, borrowIndex);
                          distributeBorrowerComp(cToken, borrower, borrowIndex);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                       * @notice Validates borrow and reverts on rejection. May emit logs.
                       * @param cToken Asset whose underlying is being borrowed
                       * @param borrower The address borrowing the underlying
                       * @param borrowAmount The amount of the underlying asset requested to borrow
                       */
                      function borrowVerify(address cToken, address borrower, uint borrowAmount) external {
                          // Shh - currently unused
                          cToken;
                          borrower;
                          borrowAmount;
                          // Shh - we don't ever want this hook to be marked pure
                          if (false) {
                              maxAssets = maxAssets;
                          }
                      }
                      /**
                       * @notice Checks if the account should be allowed to repay a borrow in the given market
                       * @param cToken The market to verify the repay against
                       * @param payer The account which would repay the asset
                       * @param borrower The account which would borrowed the asset
                       * @param repayAmount The amount of the underlying asset the account would repay
                       * @return 0 if the repay is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)
                       */
                      function repayBorrowAllowed(
                          address cToken,
                          address payer,
                          address borrower,
                          uint repayAmount) external returns (uint) {
                          // Shh - currently unused
                          payer;
                          borrower;
                          repayAmount;
                          if (!markets[cToken].isListed) {
                              return uint(Error.MARKET_NOT_LISTED);
                          }
                          // Keep the flywheel moving
                          Exp memory borrowIndex = Exp({mantissa: CToken(cToken).borrowIndex()});
                          updateCompBorrowIndex(cToken, borrowIndex);
                          distributeBorrowerComp(cToken, borrower, borrowIndex);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                       * @notice Validates repayBorrow and reverts on rejection. May emit logs.
                       * @param cToken Asset being repaid
                       * @param payer The address repaying the borrow
                       * @param borrower The address of the borrower
                       * @param actualRepayAmount The amount of underlying being repaid
                       */
                      function repayBorrowVerify(
                          address cToken,
                          address payer,
                          address borrower,
                          uint actualRepayAmount,
                          uint borrowerIndex) external {
                          // Shh - currently unused
                          cToken;
                          payer;
                          borrower;
                          actualRepayAmount;
                          borrowerIndex;
                          // Shh - we don't ever want this hook to be marked pure
                          if (false) {
                              maxAssets = maxAssets;
                          }
                      }
                      /**
                       * @notice Checks if the liquidation should be allowed to occur
                       * @param cTokenBorrowed Asset which was borrowed by the borrower
                       * @param cTokenCollateral Asset which was used as collateral and will be seized
                       * @param liquidator The address repaying the borrow and seizing the collateral
                       * @param borrower The address of the borrower
                       * @param repayAmount The amount of underlying being repaid
                       */
                      function liquidateBorrowAllowed(
                          address cTokenBorrowed,
                          address cTokenCollateral,
                          address liquidator,
                          address borrower,
                          uint repayAmount) external returns (uint) {
                          // Shh - currently unused
                          liquidator;
                          if (!markets[cTokenBorrowed].isListed || !markets[cTokenCollateral].isListed) {
                              return uint(Error.MARKET_NOT_LISTED);
                          }
                          uint borrowBalance = CToken(cTokenBorrowed).borrowBalanceStored(borrower);
                          /* allow accounts to be liquidated if the market is deprecated */
                          if (isDeprecated(CToken(cTokenBorrowed))) {
                              require(borrowBalance >= repayAmount, "Can not repay more than the total borrow");
                          } else {
                              /* The borrower must have shortfall in order to be liquidatable */
                              (Error err, , uint shortfall) = getAccountLiquidityInternal(borrower);
                              if (err != Error.NO_ERROR) {
                                  return uint(err);
                              }
                              if (shortfall == 0) {
                                  return uint(Error.INSUFFICIENT_SHORTFALL);
                              }
                              /* The liquidator may not repay more than what is allowed by the closeFactor */
                              uint maxClose = mul_ScalarTruncate(Exp({mantissa: closeFactorMantissa}), borrowBalance);
                              if (repayAmount > maxClose) {
                                  return uint(Error.TOO_MUCH_REPAY);
                              }
                          }
                          return uint(Error.NO_ERROR);
                      }
                      /**
                       * @notice Validates liquidateBorrow and reverts on rejection. May emit logs.
                       * @param cTokenBorrowed Asset which was borrowed by the borrower
                       * @param cTokenCollateral Asset which was used as collateral and will be seized
                       * @param liquidator The address repaying the borrow and seizing the collateral
                       * @param borrower The address of the borrower
                       * @param actualRepayAmount The amount of underlying being repaid
                       */
                      function liquidateBorrowVerify(
                          address cTokenBorrowed,
                          address cTokenCollateral,
                          address liquidator,
                          address borrower,
                          uint actualRepayAmount,
                          uint seizeTokens) external {
                          // Shh - currently unused
                          cTokenBorrowed;
                          cTokenCollateral;
                          liquidator;
                          borrower;
                          actualRepayAmount;
                          seizeTokens;
                          // Shh - we don't ever want this hook to be marked pure
                          if (false) {
                              maxAssets = maxAssets;
                          }
                      }
                      /**
                       * @notice Checks if the seizing of assets should be allowed to occur
                       * @param cTokenCollateral Asset which was used as collateral and will be seized
                       * @param cTokenBorrowed Asset which was borrowed by the borrower
                       * @param liquidator The address repaying the borrow and seizing the collateral
                       * @param borrower The address of the borrower
                       * @param seizeTokens The number of collateral tokens to seize
                       */
                      function seizeAllowed(
                          address cTokenCollateral,
                          address cTokenBorrowed,
                          address liquidator,
                          address borrower,
                          uint seizeTokens) external returns (uint) {
                          // Pausing is a very serious situation - we revert to sound the alarms
                          require(!seizeGuardianPaused, "seize is paused");
                          // Shh - currently unused
                          seizeTokens;
                          if (!markets[cTokenCollateral].isListed || !markets[cTokenBorrowed].isListed) {
                              return uint(Error.MARKET_NOT_LISTED);
                          }
                          if (CToken(cTokenCollateral).comptroller() != CToken(cTokenBorrowed).comptroller()) {
                              return uint(Error.COMPTROLLER_MISMATCH);
                          }
                          // Keep the flywheel moving
                          updateCompSupplyIndex(cTokenCollateral);
                          distributeSupplierComp(cTokenCollateral, borrower);
                          distributeSupplierComp(cTokenCollateral, liquidator);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                       * @notice Validates seize and reverts on rejection. May emit logs.
                       * @param cTokenCollateral Asset which was used as collateral and will be seized
                       * @param cTokenBorrowed Asset which was borrowed by the borrower
                       * @param liquidator The address repaying the borrow and seizing the collateral
                       * @param borrower The address of the borrower
                       * @param seizeTokens The number of collateral tokens to seize
                       */
                      function seizeVerify(
                          address cTokenCollateral,
                          address cTokenBorrowed,
                          address liquidator,
                          address borrower,
                          uint seizeTokens) external {
                          // Shh - currently unused
                          cTokenCollateral;
                          cTokenBorrowed;
                          liquidator;
                          borrower;
                          seizeTokens;
                          // Shh - we don't ever want this hook to be marked pure
                          if (false) {
                              maxAssets = maxAssets;
                          }
                      }
                      /**
                       * @notice Checks if the account should be allowed to transfer tokens in the given market
                       * @param cToken The market to verify the transfer against
                       * @param src The account which sources the tokens
                       * @param dst The account which receives the tokens
                       * @param transferTokens The number of cTokens to transfer
                       * @return 0 if the transfer is allowed, otherwise a semi-opaque error code (See ErrorReporter.sol)
                       */
                      function transferAllowed(address cToken, address src, address dst, uint transferTokens) external returns (uint) {
                          // Pausing is a very serious situation - we revert to sound the alarms
                          require(!transferGuardianPaused, "transfer is paused");
                          // Currently the only consideration is whether or not
                          //  the src is allowed to redeem this many tokens
                          uint allowed = redeemAllowedInternal(cToken, src, transferTokens);
                          if (allowed != uint(Error.NO_ERROR)) {
                              return allowed;
                          }
                          // Keep the flywheel moving
                          updateCompSupplyIndex(cToken);
                          distributeSupplierComp(cToken, src);
                          distributeSupplierComp(cToken, dst);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                       * @notice Validates transfer and reverts on rejection. May emit logs.
                       * @param cToken Asset being transferred
                       * @param src The account which sources the tokens
                       * @param dst The account which receives the tokens
                       * @param transferTokens The number of cTokens to transfer
                       */
                      function transferVerify(address cToken, address src, address dst, uint transferTokens) external {
                          // Shh - currently unused
                          cToken;
                          src;
                          dst;
                          transferTokens;
                          // Shh - we don't ever want this hook to be marked pure
                          if (false) {
                              maxAssets = maxAssets;
                          }
                      }
                      /*** Liquidity/Liquidation Calculations ***/
                      /**
                       * @dev Local vars for avoiding stack-depth limits in calculating account liquidity.
                       *  Note that `cTokenBalance` is the number of cTokens the account owns in the market,
                       *  whereas `borrowBalance` is the amount of underlying that the account has borrowed.
                       */
                      struct AccountLiquidityLocalVars {
                          uint sumCollateral;
                          uint sumBorrowPlusEffects;
                          uint cTokenBalance;
                          uint borrowBalance;
                          uint exchangeRateMantissa;
                          uint oraclePriceMantissa;
                          Exp collateralFactor;
                          Exp exchangeRate;
                          Exp oraclePrice;
                          Exp tokensToDenom;
                      }
                      /**
                       * @notice Determine the current account liquidity wrt collateral requirements
                       * @return (possible error code (semi-opaque),
                                  account liquidity in excess of collateral requirements,
                       *          account shortfall below collateral requirements)
                       */
                      function getAccountLiquidity(address account) public view returns (uint, uint, uint) {
                          (Error err, uint liquidity, uint shortfall) = getHypotheticalAccountLiquidityInternal(account, CToken(0), 0, 0);
                          return (uint(err), liquidity, shortfall);
                      }
                      /**
                       * @notice Determine the current account liquidity wrt collateral requirements
                       * @return (possible error code,
                                  account liquidity in excess of collateral requirements,
                       *          account shortfall below collateral requirements)
                       */
                      function getAccountLiquidityInternal(address account) internal view returns (Error, uint, uint) {
                          return getHypotheticalAccountLiquidityInternal(account, CToken(0), 0, 0);
                      }
                      /**
                       * @notice Determine what the account liquidity would be if the given amounts were redeemed/borrowed
                       * @param cTokenModify The market to hypothetically redeem/borrow in
                       * @param account The account to determine liquidity for
                       * @param redeemTokens The number of tokens to hypothetically redeem
                       * @param borrowAmount The amount of underlying to hypothetically borrow
                       * @return (possible error code (semi-opaque),
                                  hypothetical account liquidity in excess of collateral requirements,
                       *          hypothetical account shortfall below collateral requirements)
                       */
                      function getHypotheticalAccountLiquidity(
                          address account,
                          address cTokenModify,
                          uint redeemTokens,
                          uint borrowAmount) public view returns (uint, uint, uint) {
                          (Error err, uint liquidity, uint shortfall) = getHypotheticalAccountLiquidityInternal(account, CToken(cTokenModify), redeemTokens, borrowAmount);
                          return (uint(err), liquidity, shortfall);
                      }
                      /**
                       * @notice Determine what the account liquidity would be if the given amounts were redeemed/borrowed
                       * @param cTokenModify The market to hypothetically redeem/borrow in
                       * @param account The account to determine liquidity for
                       * @param redeemTokens The number of tokens to hypothetically redeem
                       * @param borrowAmount The amount of underlying to hypothetically borrow
                       * @dev Note that we calculate the exchangeRateStored for each collateral cToken using stored data,
                       *  without calculating accumulated interest.
                       * @return (possible error code,
                                  hypothetical account liquidity in excess of collateral requirements,
                       *          hypothetical account shortfall below collateral requirements)
                       */
                      function getHypotheticalAccountLiquidityInternal(
                          address account,
                          CToken cTokenModify,
                          uint redeemTokens,
                          uint borrowAmount) internal view returns (Error, uint, uint) {
                          AccountLiquidityLocalVars memory vars; // Holds all our calculation results
                          uint oErr;
                          // For each asset the account is in
                          CToken[] memory assets = accountAssets[account];
                          for (uint i = 0; i < assets.length; i++) {
                              CToken asset = assets[i];
                              // Read the balances and exchange rate from the cToken
                              (oErr, vars.cTokenBalance, vars.borrowBalance, vars.exchangeRateMantissa) = asset.getAccountSnapshot(account);
                              if (oErr != 0) { // semi-opaque error code, we assume NO_ERROR == 0 is invariant between upgrades
                                  return (Error.SNAPSHOT_ERROR, 0, 0);
                              }
                              vars.collateralFactor = Exp({mantissa: markets[address(asset)].collateralFactorMantissa});
                              vars.exchangeRate = Exp({mantissa: vars.exchangeRateMantissa});
                              // Get the normalized price of the asset
                              vars.oraclePriceMantissa = oracle.getUnderlyingPrice(asset);
                              if (vars.oraclePriceMantissa == 0) {
                                  return (Error.PRICE_ERROR, 0, 0);
                              }
                              vars.oraclePrice = Exp({mantissa: vars.oraclePriceMantissa});
                              // Pre-compute a conversion factor from tokens -> ether (normalized price value)
                              vars.tokensToDenom = mul_(mul_(vars.collateralFactor, vars.exchangeRate), vars.oraclePrice);
                              // sumCollateral += tokensToDenom * cTokenBalance
                              vars.sumCollateral = mul_ScalarTruncateAddUInt(vars.tokensToDenom, vars.cTokenBalance, vars.sumCollateral);
                              // sumBorrowPlusEffects += oraclePrice * borrowBalance
                              vars.sumBorrowPlusEffects = mul_ScalarTruncateAddUInt(vars.oraclePrice, vars.borrowBalance, vars.sumBorrowPlusEffects);
                              // Calculate effects of interacting with cTokenModify
                              if (asset == cTokenModify) {
                                  // redeem effect
                                  // sumBorrowPlusEffects += tokensToDenom * redeemTokens
                                  vars.sumBorrowPlusEffects = mul_ScalarTruncateAddUInt(vars.tokensToDenom, redeemTokens, vars.sumBorrowPlusEffects);
                                  // borrow effect
                                  // sumBorrowPlusEffects += oraclePrice * borrowAmount
                                  vars.sumBorrowPlusEffects = mul_ScalarTruncateAddUInt(vars.oraclePrice, borrowAmount, vars.sumBorrowPlusEffects);
                              }
                          }
                          // These are safe, as the underflow condition is checked first
                          if (vars.sumCollateral > vars.sumBorrowPlusEffects) {
                              return (Error.NO_ERROR, vars.sumCollateral - vars.sumBorrowPlusEffects, 0);
                          } else {
                              return (Error.NO_ERROR, 0, vars.sumBorrowPlusEffects - vars.sumCollateral);
                          }
                      }
                      /**
                       * @notice Calculate number of tokens of collateral asset to seize given an underlying amount
                       * @dev Used in liquidation (called in cToken.liquidateBorrowFresh)
                       * @param cTokenBorrowed The address of the borrowed cToken
                       * @param cTokenCollateral The address of the collateral cToken
                       * @param actualRepayAmount The amount of cTokenBorrowed underlying to convert into cTokenCollateral tokens
                       * @return (errorCode, number of cTokenCollateral tokens to be seized in a liquidation)
                       */
                      function liquidateCalculateSeizeTokens(address cTokenBorrowed, address cTokenCollateral, uint actualRepayAmount) external view returns (uint, uint) {
                          /* Read oracle prices for borrowed and collateral markets */
                          uint priceBorrowedMantissa = oracle.getUnderlyingPrice(CToken(cTokenBorrowed));
                          uint priceCollateralMantissa = oracle.getUnderlyingPrice(CToken(cTokenCollateral));
                          if (priceBorrowedMantissa == 0 || priceCollateralMantissa == 0) {
                              return (uint(Error.PRICE_ERROR), 0);
                          }
                          /*
                           * Get the exchange rate and calculate the number of collateral tokens to seize:
                           *  seizeAmount = actualRepayAmount * liquidationIncentive * priceBorrowed / priceCollateral
                           *  seizeTokens = seizeAmount / exchangeRate
                           *   = actualRepayAmount * (liquidationIncentive * priceBorrowed) / (priceCollateral * exchangeRate)
                           */
                          uint exchangeRateMantissa = CToken(cTokenCollateral).exchangeRateStored(); // Note: reverts on error
                          uint seizeTokens;
                          Exp memory numerator;
                          Exp memory denominator;
                          Exp memory ratio;
                          numerator = mul_(Exp({mantissa: liquidationIncentiveMantissa}), Exp({mantissa: priceBorrowedMantissa}));
                          denominator = mul_(Exp({mantissa: priceCollateralMantissa}), Exp({mantissa: exchangeRateMantissa}));
                          ratio = div_(numerator, denominator);
                          seizeTokens = mul_ScalarTruncate(ratio, actualRepayAmount);
                          return (uint(Error.NO_ERROR), seizeTokens);
                      }
                      /*** Admin Functions ***/
                      /**
                        * @notice Sets a new price oracle for the comptroller
                        * @dev Admin function to set a new price oracle
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function _setPriceOracle(PriceOracle newOracle) public returns (uint) {
                          // Check caller is admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_PRICE_ORACLE_OWNER_CHECK);
                          }
                          // Track the old oracle for the comptroller
                          PriceOracle oldOracle = oracle;
                          // Set comptroller's oracle to newOracle
                          oracle = newOracle;
                          // Emit NewPriceOracle(oldOracle, newOracle)
                          emit NewPriceOracle(oldOracle, newOracle);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                        * @notice Sets the closeFactor used when liquidating borrows
                        * @dev Admin function to set closeFactor
                        * @param newCloseFactorMantissa New close factor, scaled by 1e18
                        * @return uint 0=success, otherwise a failure
                        */
                      function _setCloseFactor(uint newCloseFactorMantissa) external returns (uint) {
                          // Check caller is admin
                      \trequire(msg.sender == admin, "only admin can set close factor");
                          uint oldCloseFactorMantissa = closeFactorMantissa;
                          closeFactorMantissa = newCloseFactorMantissa;
                          emit NewCloseFactor(oldCloseFactorMantissa, closeFactorMantissa);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                        * @notice Sets the collateralFactor for a market
                        * @dev Admin function to set per-market collateralFactor
                        * @param cToken The market to set the factor on
                        * @param newCollateralFactorMantissa The new collateral factor, scaled by 1e18
                        * @return uint 0=success, otherwise a failure. (See ErrorReporter for details)
                        */
                      function _setCollateralFactor(CToken cToken, uint newCollateralFactorMantissa) external returns (uint) {
                          // Check caller is admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_COLLATERAL_FACTOR_OWNER_CHECK);
                          }
                          // Verify market is listed
                          Market storage market = markets[address(cToken)];
                          if (!market.isListed) {
                              return fail(Error.MARKET_NOT_LISTED, FailureInfo.SET_COLLATERAL_FACTOR_NO_EXISTS);
                          }
                          Exp memory newCollateralFactorExp = Exp({mantissa: newCollateralFactorMantissa});
                          // Check collateral factor <= 0.9
                          Exp memory highLimit = Exp({mantissa: collateralFactorMaxMantissa});
                          if (lessThanExp(highLimit, newCollateralFactorExp)) {
                              return fail(Error.INVALID_COLLATERAL_FACTOR, FailureInfo.SET_COLLATERAL_FACTOR_VALIDATION);
                          }
                          // If collateral factor != 0, fail if price == 0
                          if (newCollateralFactorMantissa != 0 && oracle.getUnderlyingPrice(cToken) == 0) {
                              return fail(Error.PRICE_ERROR, FailureInfo.SET_COLLATERAL_FACTOR_WITHOUT_PRICE);
                          }
                          // Set market's collateral factor to new collateral factor, remember old value
                          uint oldCollateralFactorMantissa = market.collateralFactorMantissa;
                          market.collateralFactorMantissa = newCollateralFactorMantissa;
                          // Emit event with asset, old collateral factor, and new collateral factor
                          emit NewCollateralFactor(cToken, oldCollateralFactorMantissa, newCollateralFactorMantissa);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                        * @notice Sets liquidationIncentive
                        * @dev Admin function to set liquidationIncentive
                        * @param newLiquidationIncentiveMantissa New liquidationIncentive scaled by 1e18
                        * @return uint 0=success, otherwise a failure. (See ErrorReporter for details)
                        */
                      function _setLiquidationIncentive(uint newLiquidationIncentiveMantissa) external returns (uint) {
                          // Check caller is admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_LIQUIDATION_INCENTIVE_OWNER_CHECK);
                          }
                          // Save current value for use in log
                          uint oldLiquidationIncentiveMantissa = liquidationIncentiveMantissa;
                          // Set liquidation incentive to new incentive
                          liquidationIncentiveMantissa = newLiquidationIncentiveMantissa;
                          // Emit event with old incentive, new incentive
                          emit NewLiquidationIncentive(oldLiquidationIncentiveMantissa, newLiquidationIncentiveMantissa);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                        * @notice Add the market to the markets mapping and set it as listed
                        * @dev Admin function to set isListed and add support for the market
                        * @param cToken The address of the market (token) to list
                        * @return uint 0=success, otherwise a failure. (See enum Error for details)
                        */
                      function _supportMarket(CToken cToken) external returns (uint) {
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SUPPORT_MARKET_OWNER_CHECK);
                          }
                          if (markets[address(cToken)].isListed) {
                              return fail(Error.MARKET_ALREADY_LISTED, FailureInfo.SUPPORT_MARKET_EXISTS);
                          }
                          cToken.isCToken(); // Sanity check to make sure its really a CToken
                          // Note that isComped is not in active use anymore
                          markets[address(cToken)] = Market({isListed: true, isComped: false, collateralFactorMantissa: 0});
                          _addMarketInternal(address(cToken));
                          _initializeMarket(address(cToken));
                          emit MarketListed(cToken);
                          return uint(Error.NO_ERROR);
                      }
                      function _addMarketInternal(address cToken) internal {
                          for (uint i = 0; i < allMarkets.length; i ++) {
                              require(allMarkets[i] != CToken(cToken), "market already added");
                          }
                          allMarkets.push(CToken(cToken));
                      }
                      function _initializeMarket(address cToken) internal {
                          uint32 blockNumber = safe32(getBlockNumber(), "block number exceeds 32 bits");
                          CompMarketState storage supplyState = compSupplyState[cToken];
                          CompMarketState storage borrowState = compBorrowState[cToken];
                          /*
                           * Update market state indices
                           */
                          if (supplyState.index == 0) {
                              // Initialize supply state index with default value
                              supplyState.index = compInitialIndex;
                          }
                          if (borrowState.index == 0) {
                              // Initialize borrow state index with default value
                              borrowState.index = compInitialIndex;
                          }
                          /*
                           * Update market state block numbers
                           */
                           supplyState.block = borrowState.block = blockNumber;
                      }
                      /**
                        * @notice Set the given borrow caps for the given cToken markets. Borrowing that brings total borrows to or above borrow cap will revert.
                        * @dev Admin or borrowCapGuardian function to set the borrow caps. A borrow cap of 0 corresponds to unlimited borrowing.
                        * @param cTokens The addresses of the markets (tokens) to change the borrow caps for
                        * @param newBorrowCaps The new borrow cap values in underlying to be set. A value of 0 corresponds to unlimited borrowing.
                        */
                      function _setMarketBorrowCaps(CToken[] calldata cTokens, uint[] calldata newBorrowCaps) external {
                      \trequire(msg.sender == admin || msg.sender == borrowCapGuardian, "only admin or borrow cap guardian can set borrow caps"); 
                          uint numMarkets = cTokens.length;
                          uint numBorrowCaps = newBorrowCaps.length;
                          require(numMarkets != 0 && numMarkets == numBorrowCaps, "invalid input");
                          for(uint i = 0; i < numMarkets; i++) {
                              borrowCaps[address(cTokens[i])] = newBorrowCaps[i];
                              emit NewBorrowCap(cTokens[i], newBorrowCaps[i]);
                          }
                      }
                      /**
                       * @notice Admin function to change the Borrow Cap Guardian
                       * @param newBorrowCapGuardian The address of the new Borrow Cap Guardian
                       */
                      function _setBorrowCapGuardian(address newBorrowCapGuardian) external {
                          require(msg.sender == admin, "only admin can set borrow cap guardian");
                          // Save current value for inclusion in log
                          address oldBorrowCapGuardian = borrowCapGuardian;
                          // Store borrowCapGuardian with value newBorrowCapGuardian
                          borrowCapGuardian = newBorrowCapGuardian;
                          // Emit NewBorrowCapGuardian(OldBorrowCapGuardian, NewBorrowCapGuardian)
                          emit NewBorrowCapGuardian(oldBorrowCapGuardian, newBorrowCapGuardian);
                      }
                      /**
                       * @notice Admin function to change the Pause Guardian
                       * @param newPauseGuardian The address of the new Pause Guardian
                       * @return uint 0=success, otherwise a failure. (See enum Error for details)
                       */
                      function _setPauseGuardian(address newPauseGuardian) public returns (uint) {
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_PAUSE_GUARDIAN_OWNER_CHECK);
                          }
                          // Save current value for inclusion in log
                          address oldPauseGuardian = pauseGuardian;
                          // Store pauseGuardian with value newPauseGuardian
                          pauseGuardian = newPauseGuardian;
                          // Emit NewPauseGuardian(OldPauseGuardian, NewPauseGuardian)
                          emit NewPauseGuardian(oldPauseGuardian, pauseGuardian);
                          return uint(Error.NO_ERROR);
                      }
                      function _setMintPaused(CToken cToken, bool state) public returns (bool) {
                          require(markets[address(cToken)].isListed, "cannot pause a market that is not listed");
                          require(msg.sender == pauseGuardian || msg.sender == admin, "only pause guardian and admin can pause");
                          require(msg.sender == admin || state == true, "only admin can unpause");
                          mintGuardianPaused[address(cToken)] = state;
                          emit ActionPaused(cToken, "Mint", state);
                          return state;
                      }
                      function _setBorrowPaused(CToken cToken, bool state) public returns (bool) {
                          require(markets[address(cToken)].isListed, "cannot pause a market that is not listed");
                          require(msg.sender == pauseGuardian || msg.sender == admin, "only pause guardian and admin can pause");
                          require(msg.sender == admin || state == true, "only admin can unpause");
                          borrowGuardianPaused[address(cToken)] = state;
                          emit ActionPaused(cToken, "Borrow", state);
                          return state;
                      }
                      function _setTransferPaused(bool state) public returns (bool) {
                          require(msg.sender == pauseGuardian || msg.sender == admin, "only pause guardian and admin can pause");
                          require(msg.sender == admin || state == true, "only admin can unpause");
                          transferGuardianPaused = state;
                          emit ActionPaused("Transfer", state);
                          return state;
                      }
                      function _setSeizePaused(bool state) public returns (bool) {
                          require(msg.sender == pauseGuardian || msg.sender == admin, "only pause guardian and admin can pause");
                          require(msg.sender == admin || state == true, "only admin can unpause");
                          seizeGuardianPaused = state;
                          emit ActionPaused("Seize", state);
                          return state;
                      }
                      function _become(Unitroller unitroller) public {
                          require(msg.sender == unitroller.admin(), "only unitroller admin can change brains");
                          require(unitroller._acceptImplementation() == 0, "change not authorized");
                      }
                      /// @notice Delete this function after proposal 65 is executed
                      function fixBadAccruals(address[] calldata affectedUsers, uint[] calldata amounts) external {
                          require(msg.sender == admin, "Only admin can call this function"); // Only the timelock can call this function
                          require(!proposal65FixExecuted, "Already executed this one-off function"); // Require that this function is only called once
                          require(affectedUsers.length == amounts.length, "Invalid input");
                          // Loop variables
                          address user;
                          uint currentAccrual;
                          uint amountToSubtract;
                          uint newAccrual;
                          // Iterate through all affected users
                          for (uint i = 0; i < affectedUsers.length; ++i) {
                              user = affectedUsers[i];
                              currentAccrual = compAccrued[user];
                              amountToSubtract = amounts[i];
                              // The case where the user has claimed and received an incorrect amount of COMP.
                              // The user has less currently accrued than the amount they incorrectly received.
                              if (amountToSubtract > currentAccrual) {
                                  // Amount of COMP the user owes the protocol
                                  uint accountReceivable = amountToSubtract - currentAccrual; // Underflow safe since amountToSubtract > currentAccrual
                                  uint oldReceivable = compReceivable[user];
                                  uint newReceivable = add_(oldReceivable, accountReceivable);
                                  // Accounting: record the COMP debt for the user
                                  compReceivable[user] = newReceivable;
                                  emit CompReceivableUpdated(user, oldReceivable, newReceivable);
                                  amountToSubtract = currentAccrual;
                              }
                              
                              if (amountToSubtract > 0) {
                                  // Subtract the bad accrual amount from what they have accrued.
                                  // Users will keep whatever they have correctly accrued.
                                  compAccrued[user] = newAccrual = sub_(currentAccrual, amountToSubtract);
                                  emit CompAccruedAdjusted(user, currentAccrual, newAccrual);
                              }
                          }
                          proposal65FixExecuted = true; // Makes it so that this function cannot be called again
                      }
                      /**
                       * @notice Checks caller is admin, or this contract is becoming the new implementation
                       */
                      function adminOrInitializing() internal view returns (bool) {
                          return msg.sender == admin || msg.sender == comptrollerImplementation;
                      }
                      /*** Comp Distribution ***/
                      /**
                       * @notice Set COMP speed for a single market
                       * @param cToken The market whose COMP speed to update
                       * @param supplySpeed New supply-side COMP speed for market
                       * @param borrowSpeed New borrow-side COMP speed for market
                       */
                      function setCompSpeedInternal(CToken cToken, uint supplySpeed, uint borrowSpeed) internal {
                          Market storage market = markets[address(cToken)];
                          require(market.isListed, "comp market is not listed");
                          if (compSupplySpeeds[address(cToken)] != supplySpeed) {
                              // Supply speed updated so let's update supply state to ensure that
                              //  1. COMP accrued properly for the old speed, and
                              //  2. COMP accrued at the new speed starts after this block.
                              updateCompSupplyIndex(address(cToken));
                              // Update speed and emit event
                              compSupplySpeeds[address(cToken)] = supplySpeed;
                              emit CompSupplySpeedUpdated(cToken, supplySpeed);
                          }
                          if (compBorrowSpeeds[address(cToken)] != borrowSpeed) {
                              // Borrow speed updated so let's update borrow state to ensure that
                              //  1. COMP accrued properly for the old speed, and
                              //  2. COMP accrued at the new speed starts after this block.
                              Exp memory borrowIndex = Exp({mantissa: cToken.borrowIndex()});
                              updateCompBorrowIndex(address(cToken), borrowIndex);
                              // Update speed and emit event
                              compBorrowSpeeds[address(cToken)] = borrowSpeed;
                              emit CompBorrowSpeedUpdated(cToken, borrowSpeed);
                          }
                      }
                      /**
                       * @notice Accrue COMP to the market by updating the supply index
                       * @param cToken The market whose supply index to update
                       * @dev Index is a cumulative sum of the COMP per cToken accrued.
                       */
                      function updateCompSupplyIndex(address cToken) internal {
                          CompMarketState storage supplyState = compSupplyState[cToken];
                          uint supplySpeed = compSupplySpeeds[cToken];
                          uint32 blockNumber = safe32(getBlockNumber(), "block number exceeds 32 bits");
                          uint deltaBlocks = sub_(uint(blockNumber), uint(supplyState.block));
                          if (deltaBlocks > 0 && supplySpeed > 0) {
                              uint supplyTokens = CToken(cToken).totalSupply();
                              uint compAccrued = mul_(deltaBlocks, supplySpeed);
                              Double memory ratio = supplyTokens > 0 ? fraction(compAccrued, supplyTokens) : Double({mantissa: 0});
                              supplyState.index = safe224(add_(Double({mantissa: supplyState.index}), ratio).mantissa, "new index exceeds 224 bits");
                              supplyState.block = blockNumber;
                          } else if (deltaBlocks > 0) {
                              supplyState.block = blockNumber;
                          }
                      }
                      /**
                       * @notice Accrue COMP to the market by updating the borrow index
                       * @param cToken The market whose borrow index to update
                       * @dev Index is a cumulative sum of the COMP per cToken accrued.
                       */
                      function updateCompBorrowIndex(address cToken, Exp memory marketBorrowIndex) internal {
                          CompMarketState storage borrowState = compBorrowState[cToken];
                          uint borrowSpeed = compBorrowSpeeds[cToken];
                          uint32 blockNumber = safe32(getBlockNumber(), "block number exceeds 32 bits");
                          uint deltaBlocks = sub_(uint(blockNumber), uint(borrowState.block));
                          if (deltaBlocks > 0 && borrowSpeed > 0) {
                              uint borrowAmount = div_(CToken(cToken).totalBorrows(), marketBorrowIndex);
                              uint compAccrued = mul_(deltaBlocks, borrowSpeed);
                              Double memory ratio = borrowAmount > 0 ? fraction(compAccrued, borrowAmount) : Double({mantissa: 0});
                              borrowState.index = safe224(add_(Double({mantissa: borrowState.index}), ratio).mantissa, "new index exceeds 224 bits");
                              borrowState.block = blockNumber;
                          } else if (deltaBlocks > 0) {
                              borrowState.block = blockNumber;
                          }
                      }
                      /**
                       * @notice Calculate COMP accrued by a supplier and possibly transfer it to them
                       * @param cToken The market in which the supplier is interacting
                       * @param supplier The address of the supplier to distribute COMP to
                       */
                      function distributeSupplierComp(address cToken, address supplier) internal {
                          // TODO: Don't distribute supplier COMP if the user is not in the supplier market.
                          // This check should be as gas efficient as possible as distributeSupplierComp is called in many places.
                          // - We really don't want to call an external contract as that's quite expensive.
                          CompMarketState storage supplyState = compSupplyState[cToken];
                          uint supplyIndex = supplyState.index;
                          uint supplierIndex = compSupplierIndex[cToken][supplier];
                          // Update supplier's index to the current index since we are distributing accrued COMP
                          compSupplierIndex[cToken][supplier] = supplyIndex;
                          if (supplierIndex == 0 && supplyIndex >= compInitialIndex) {
                              // Covers the case where users supplied tokens before the market's supply state index was set.
                              // Rewards the user with COMP accrued from the start of when supplier rewards were first
                              // set for the market.
                              supplierIndex = compInitialIndex;
                          }
                          // Calculate change in the cumulative sum of the COMP per cToken accrued
                          Double memory deltaIndex = Double({mantissa: sub_(supplyIndex, supplierIndex)});
                          uint supplierTokens = CToken(cToken).balanceOf(supplier);
                          // Calculate COMP accrued: cTokenAmount * accruedPerCToken
                          uint supplierDelta = mul_(supplierTokens, deltaIndex);
                          uint supplierAccrued = add_(compAccrued[supplier], supplierDelta);
                          compAccrued[supplier] = supplierAccrued;
                          emit DistributedSupplierComp(CToken(cToken), supplier, supplierDelta, supplyIndex);
                      }
                      /**
                       * @notice Calculate COMP accrued by a borrower and possibly transfer it to them
                       * @dev Borrowers will not begin to accrue until after the first interaction with the protocol.
                       * @param cToken The market in which the borrower is interacting
                       * @param borrower The address of the borrower to distribute COMP to
                       */
                      function distributeBorrowerComp(address cToken, address borrower, Exp memory marketBorrowIndex) internal {
                          // TODO: Don't distribute supplier COMP if the user is not in the borrower market.
                          // This check should be as gas efficient as possible as distributeBorrowerComp is called in many places.
                          // - We really don't want to call an external contract as that's quite expensive.
                          CompMarketState storage borrowState = compBorrowState[cToken];
                          uint borrowIndex = borrowState.index;
                          uint borrowerIndex = compBorrowerIndex[cToken][borrower];
                          // Update borrowers's index to the current index since we are distributing accrued COMP
                          compBorrowerIndex[cToken][borrower] = borrowIndex;
                          if (borrowerIndex == 0 && borrowIndex >= compInitialIndex) {
                              // Covers the case where users borrowed tokens before the market's borrow state index was set.
                              // Rewards the user with COMP accrued from the start of when borrower rewards were first
                              // set for the market.
                              borrowerIndex = compInitialIndex;
                          }
                          // Calculate change in the cumulative sum of the COMP per borrowed unit accrued
                          Double memory deltaIndex = Double({mantissa: sub_(borrowIndex, borrowerIndex)});
                          uint borrowerAmount = div_(CToken(cToken).borrowBalanceStored(borrower), marketBorrowIndex);
                          
                          // Calculate COMP accrued: cTokenAmount * accruedPerBorrowedUnit
                          uint borrowerDelta = mul_(borrowerAmount, deltaIndex);
                          uint borrowerAccrued = add_(compAccrued[borrower], borrowerDelta);
                          compAccrued[borrower] = borrowerAccrued;
                          emit DistributedBorrowerComp(CToken(cToken), borrower, borrowerDelta, borrowIndex);
                      }
                      /**
                       * @notice Calculate additional accrued COMP for a contributor since last accrual
                       * @param contributor The address to calculate contributor rewards for
                       */
                      function updateContributorRewards(address contributor) public {
                          uint compSpeed = compContributorSpeeds[contributor];
                          uint blockNumber = getBlockNumber();
                          uint deltaBlocks = sub_(blockNumber, lastContributorBlock[contributor]);
                          if (deltaBlocks > 0 && compSpeed > 0) {
                              uint newAccrued = mul_(deltaBlocks, compSpeed);
                              uint contributorAccrued = add_(compAccrued[contributor], newAccrued);
                              compAccrued[contributor] = contributorAccrued;
                              lastContributorBlock[contributor] = blockNumber;
                          }
                      }
                      /**
                       * @notice Claim all the comp accrued by holder in all markets
                       * @param holder The address to claim COMP for
                       */
                      function claimComp(address holder) public {
                          return claimComp(holder, allMarkets);
                      }
                      /**
                       * @notice Claim all the comp accrued by holder in the specified markets
                       * @param holder The address to claim COMP for
                       * @param cTokens The list of markets to claim COMP in
                       */
                      function claimComp(address holder, CToken[] memory cTokens) public {
                          address[] memory holders = new address[](1);
                          holders[0] = holder;
                          claimComp(holders, cTokens, true, true);
                      }
                      /**
                       * @notice Claim all comp accrued by the holders
                       * @param holders The addresses to claim COMP for
                       * @param cTokens The list of markets to claim COMP in
                       * @param borrowers Whether or not to claim COMP earned by borrowing
                       * @param suppliers Whether or not to claim COMP earned by supplying
                       */
                      function claimComp(address[] memory holders, CToken[] memory cTokens, bool borrowers, bool suppliers) public {
                          for (uint i = 0; i < cTokens.length; i++) {
                              CToken cToken = cTokens[i];
                              require(markets[address(cToken)].isListed, "market must be listed");
                              if (borrowers == true) {
                                  Exp memory borrowIndex = Exp({mantissa: cToken.borrowIndex()});
                                  updateCompBorrowIndex(address(cToken), borrowIndex);
                                  for (uint j = 0; j < holders.length; j++) {
                                      distributeBorrowerComp(address(cToken), holders[j], borrowIndex);
                                  }
                              }
                              if (suppliers == true) {
                                  updateCompSupplyIndex(address(cToken));
                                  for (uint j = 0; j < holders.length; j++) {
                                      distributeSupplierComp(address(cToken), holders[j]);
                                  }
                              }
                          }
                          for (uint j = 0; j < holders.length; j++) {
                              compAccrued[holders[j]] = grantCompInternal(holders[j], compAccrued[holders[j]]);
                          }
                      }
                      /**
                       * @notice Transfer COMP to the user
                       * @dev Note: If there is not enough COMP, we do not perform the transfer all.
                       * @param user The address of the user to transfer COMP to
                       * @param amount The amount of COMP to (possibly) transfer
                       * @return The amount of COMP which was NOT transferred to the user
                       */
                      function grantCompInternal(address user, uint amount) internal returns (uint) {
                          Comp comp = Comp(getCompAddress());
                          uint compRemaining = comp.balanceOf(address(this));
                          if (amount > 0 && amount <= compRemaining) {
                              comp.transfer(user, amount);
                              return 0;
                          }
                          return amount;
                      }
                      /*** Comp Distribution Admin ***/
                      /**
                       * @notice Transfer COMP to the recipient
                       * @dev Note: If there is not enough COMP, we do not perform the transfer all.
                       * @param recipient The address of the recipient to transfer COMP to
                       * @param amount The amount of COMP to (possibly) transfer
                       */
                      function _grantComp(address recipient, uint amount) public {
                          require(adminOrInitializing(), "only admin can grant comp");
                          uint amountLeft = grantCompInternal(recipient, amount);
                          require(amountLeft == 0, "insufficient comp for grant");
                          emit CompGranted(recipient, amount);
                      }
                      /**
                       * @notice Set COMP borrow and supply speeds for the specified markets.
                       * @param cTokens The markets whose COMP speed to update.
                       * @param supplySpeeds New supply-side COMP speed for the corresponding market.
                       * @param borrowSpeeds New borrow-side COMP speed for the corresponding market.
                       */
                      function _setCompSpeeds(CToken[] memory cTokens, uint[] memory supplySpeeds, uint[] memory borrowSpeeds) public {
                          require(adminOrInitializing(), "only admin can set comp speed");
                          uint numTokens = cTokens.length;
                          require(numTokens == supplySpeeds.length && numTokens == borrowSpeeds.length, "Comptroller::_setCompSpeeds invalid input");
                          for (uint i = 0; i < numTokens; ++i) {
                              setCompSpeedInternal(cTokens[i], supplySpeeds[i], borrowSpeeds[i]);
                          }
                      }
                      /**
                       * @notice Set COMP speed for a single contributor
                       * @param contributor The contributor whose COMP speed to update
                       * @param compSpeed New COMP speed for contributor
                       */
                      function _setContributorCompSpeed(address contributor, uint compSpeed) public {
                          require(adminOrInitializing(), "only admin can set comp speed");
                          // note that COMP speed could be set to 0 to halt liquidity rewards for a contributor
                          updateContributorRewards(contributor);
                          if (compSpeed == 0) {
                              // release storage
                              delete lastContributorBlock[contributor];
                          } else {
                              lastContributorBlock[contributor] = getBlockNumber();
                          }
                          compContributorSpeeds[contributor] = compSpeed;
                          emit ContributorCompSpeedUpdated(contributor, compSpeed);
                      }
                      /**
                       * @notice Return all of the markets
                       * @dev The automatic getter may be used to access an individual market.
                       * @return The list of market addresses
                       */
                      function getAllMarkets() public view returns (CToken[] memory) {
                          return allMarkets;
                      }
                      /**
                       * @notice Returns true if the given cToken market has been deprecated
                       * @dev All borrows in a deprecated cToken market can be immediately liquidated
                       * @param cToken The market to check if deprecated
                       */
                      function isDeprecated(CToken cToken) public view returns (bool) {
                          return
                              markets[address(cToken)].collateralFactorMantissa == 0 && 
                              borrowGuardianPaused[address(cToken)] == true && 
                              cToken.reserveFactorMantissa() == 1e18
                          ;
                      }
                      function getBlockNumber() public view returns (uint) {
                          return block.number;
                      }
                      /**
                       * @notice Return the address of the COMP token
                       * @return The address of COMP
                       */
                      function getCompAddress() public view returns (address) {
                          return 0xc00e94Cb662C3520282E6f5717214004A7f26888;
                      }
                  }
                  pragma solidity ^0.5.16;
                  contract ComptrollerInterface {
                      /// @notice Indicator that this is a Comptroller contract (for inspection)
                      bool public constant isComptroller = true;
                      /*** Assets You Are In ***/
                      function enterMarkets(address[] calldata cTokens) external returns (uint[] memory);
                      function exitMarket(address cToken) external returns (uint);
                      /*** Policy Hooks ***/
                      function mintAllowed(address cToken, address minter, uint mintAmount) external returns (uint);
                      function mintVerify(address cToken, address minter, uint mintAmount, uint mintTokens) external;
                      function redeemAllowed(address cToken, address redeemer, uint redeemTokens) external returns (uint);
                      function redeemVerify(address cToken, address redeemer, uint redeemAmount, uint redeemTokens) external;
                      function borrowAllowed(address cToken, address borrower, uint borrowAmount) external returns (uint);
                      function borrowVerify(address cToken, address borrower, uint borrowAmount) external;
                      function repayBorrowAllowed(
                          address cToken,
                          address payer,
                          address borrower,
                          uint repayAmount) external returns (uint);
                      function repayBorrowVerify(
                          address cToken,
                          address payer,
                          address borrower,
                          uint repayAmount,
                          uint borrowerIndex) external;
                      function liquidateBorrowAllowed(
                          address cTokenBorrowed,
                          address cTokenCollateral,
                          address liquidator,
                          address borrower,
                          uint repayAmount) external returns (uint);
                      function liquidateBorrowVerify(
                          address cTokenBorrowed,
                          address cTokenCollateral,
                          address liquidator,
                          address borrower,
                          uint repayAmount,
                          uint seizeTokens) external;
                      function seizeAllowed(
                          address cTokenCollateral,
                          address cTokenBorrowed,
                          address liquidator,
                          address borrower,
                          uint seizeTokens) external returns (uint);
                      function seizeVerify(
                          address cTokenCollateral,
                          address cTokenBorrowed,
                          address liquidator,
                          address borrower,
                          uint seizeTokens) external;
                      function transferAllowed(address cToken, address src, address dst, uint transferTokens) external returns (uint);
                      function transferVerify(address cToken, address src, address dst, uint transferTokens) external;
                      /*** Liquidity/Liquidation Calculations ***/
                      function liquidateCalculateSeizeTokens(
                          address cTokenBorrowed,
                          address cTokenCollateral,
                          uint repayAmount) external view returns (uint, uint);
                  }
                  pragma solidity ^0.5.16;
                  import "./CToken.sol";
                  import "./PriceOracle.sol";
                  contract UnitrollerAdminStorage {
                      /**
                      * @notice Administrator for this contract
                      */
                      address public admin;
                      /**
                      * @notice Pending administrator for this contract
                      */
                      address public pendingAdmin;
                      /**
                      * @notice Active brains of Unitroller
                      */
                      address public comptrollerImplementation;
                      /**
                      * @notice Pending brains of Unitroller
                      */
                      address public pendingComptrollerImplementation;
                  }
                  contract ComptrollerV1Storage is UnitrollerAdminStorage {
                      /**
                       * @notice Oracle which gives the price of any given asset
                       */
                      PriceOracle public oracle;
                      /**
                       * @notice Multiplier used to calculate the maximum repayAmount when liquidating a borrow
                       */
                      uint public closeFactorMantissa;
                      /**
                       * @notice Multiplier representing the discount on collateral that a liquidator receives
                       */
                      uint public liquidationIncentiveMantissa;
                      /**
                       * @notice Max number of assets a single account can participate in (borrow or use as collateral)
                       */
                      uint public maxAssets;
                      /**
                       * @notice Per-account mapping of "assets you are in", capped by maxAssets
                       */
                      mapping(address => CToken[]) public accountAssets;
                  }
                  contract ComptrollerV2Storage is ComptrollerV1Storage {
                      struct Market {
                          /// @notice Whether or not this market is listed
                          bool isListed;
                          /**
                           * @notice Multiplier representing the most one can borrow against their collateral in this market.
                           *  For instance, 0.9 to allow borrowing 90% of collateral value.
                           *  Must be between 0 and 1, and stored as a mantissa.
                           */
                          uint collateralFactorMantissa;
                          /// @notice Per-market mapping of "accounts in this asset"
                          mapping(address => bool) accountMembership;
                          /// @notice Whether or not this market receives COMP
                          bool isComped;
                      }
                      /**
                       * @notice Official mapping of cTokens -> Market metadata
                       * @dev Used e.g. to determine if a market is supported
                       */
                      mapping(address => Market) public markets;
                      /**
                       * @notice The Pause Guardian can pause certain actions as a safety mechanism.
                       *  Actions which allow users to remove their own assets cannot be paused.
                       *  Liquidation / seizing / transfer can only be paused globally, not by market.
                       */
                      address public pauseGuardian;
                      bool public _mintGuardianPaused;
                      bool public _borrowGuardianPaused;
                      bool public transferGuardianPaused;
                      bool public seizeGuardianPaused;
                      mapping(address => bool) public mintGuardianPaused;
                      mapping(address => bool) public borrowGuardianPaused;
                  }
                  contract ComptrollerV3Storage is ComptrollerV2Storage {
                      struct CompMarketState {
                          /// @notice The market's last updated compBorrowIndex or compSupplyIndex
                          uint224 index;
                          /// @notice The block number the index was last updated at
                          uint32 block;
                      }
                      /// @notice A list of all markets
                      CToken[] public allMarkets;
                      /// @notice The rate at which the flywheel distributes COMP, per block
                      uint public compRate;
                      /// @notice The portion of compRate that each market currently receives
                      mapping(address => uint) public compSpeeds;
                      /// @notice The COMP market supply state for each market
                      mapping(address => CompMarketState) public compSupplyState;
                      /// @notice The COMP market borrow state for each market
                      mapping(address => CompMarketState) public compBorrowState;
                      /// @notice The COMP borrow index for each market for each supplier as of the last time they accrued COMP
                      mapping(address => mapping(address => uint)) public compSupplierIndex;
                      /// @notice The COMP borrow index for each market for each borrower as of the last time they accrued COMP
                      mapping(address => mapping(address => uint)) public compBorrowerIndex;
                      /// @notice The COMP accrued but not yet transferred to each user
                      mapping(address => uint) public compAccrued;
                  }
                  contract ComptrollerV4Storage is ComptrollerV3Storage {
                      // @notice The borrowCapGuardian can set borrowCaps to any number for any market. Lowering the borrow cap could disable borrowing on the given market.
                      address public borrowCapGuardian;
                      // @notice Borrow caps enforced by borrowAllowed for each cToken address. Defaults to zero which corresponds to unlimited borrowing.
                      mapping(address => uint) public borrowCaps;
                  }
                  contract ComptrollerV5Storage is ComptrollerV4Storage {
                      /// @notice The portion of COMP that each contributor receives per block
                      mapping(address => uint) public compContributorSpeeds;
                      /// @notice Last block at which a contributor's COMP rewards have been allocated
                      mapping(address => uint) public lastContributorBlock;
                  }
                  contract ComptrollerV6Storage is ComptrollerV5Storage {
                      /// @notice The rate at which comp is distributed to the corresponding borrow market (per block)
                      mapping(address => uint) public compBorrowSpeeds;
                      /// @notice The rate at which comp is distributed to the corresponding supply market (per block)
                      mapping(address => uint) public compSupplySpeeds;
                  }
                  contract ComptrollerV7Storage is ComptrollerV6Storage {
                      /// @notice Flag indicating whether the function to fix COMP accruals has been executed (RE: proposal 62 bug)
                      bool public proposal65FixExecuted;
                      /// @notice Accounting storage mapping account addresses to how much COMP they owe the protocol.
                      mapping(address => uint) public compReceivable;
                  }
                  pragma solidity ^0.5.16;
                  /**
                   * @title ERC 20 Token Standard Interface
                   *  https://eips.ethereum.org/EIPS/eip-20
                   */
                  interface EIP20Interface {
                      function name() external view returns (string memory);
                      function symbol() external view returns (string memory);
                      function decimals() external view returns (uint8);
                      /**
                        * @notice Get the total number of tokens in circulation
                        * @return The supply of tokens
                        */
                      function totalSupply() external view returns (uint256);
                      /**
                       * @notice Gets the balance of the specified address
                       * @param owner The address from which the balance will be retrieved
                       * @return The balance
                       */
                      function balanceOf(address owner) external view returns (uint256 balance);
                      /**
                        * @notice Transfer `amount` tokens from `msg.sender` to `dst`
                        * @param dst The address of the destination account
                        * @param amount The number of tokens to transfer
                        * @return Whether or not the transfer succeeded
                        */
                      function transfer(address dst, uint256 amount) external returns (bool success);
                      /**
                        * @notice Transfer `amount` tokens from `src` to `dst`
                        * @param src The address of the source account
                        * @param dst The address of the destination account
                        * @param amount The number of tokens to transfer
                        * @return Whether or not the transfer succeeded
                        */
                      function transferFrom(address src, address dst, uint256 amount) external returns (bool success);
                      /**
                        * @notice Approve `spender` to transfer up to `amount` from `src`
                        * @dev This will overwrite the approval amount for `spender`
                        *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
                        * @param spender The address of the account which may transfer tokens
                        * @param amount The number of tokens that are approved (-1 means infinite)
                        * @return Whether or not the approval succeeded
                        */
                      function approve(address spender, uint256 amount) external returns (bool success);
                      /**
                        * @notice Get the current allowance from `owner` for `spender`
                        * @param owner The address of the account which owns the tokens to be spent
                        * @param spender The address of the account which may transfer tokens
                        * @return The number of tokens allowed to be spent (-1 means infinite)
                        */
                      function allowance(address owner, address spender) external view returns (uint256 remaining);
                      event Transfer(address indexed from, address indexed to, uint256 amount);
                      event Approval(address indexed owner, address indexed spender, uint256 amount);
                  }
                  pragma solidity ^0.5.16;
                  /**
                   * @title EIP20NonStandardInterface
                   * @dev Version of ERC20 with no return values for `transfer` and `transferFrom`
                   *  See https://medium.com/coinmonks/missing-return-value-bug-at-least-130-tokens-affected-d67bf08521ca
                   */
                  interface EIP20NonStandardInterface {
                      /**
                       * @notice Get the total number of tokens in circulation
                       * @return The supply of tokens
                       */
                      function totalSupply() external view returns (uint256);
                      /**
                       * @notice Gets the balance of the specified address
                       * @param owner The address from which the balance will be retrieved
                       * @return The balance
                       */
                      function balanceOf(address owner) external view returns (uint256 balance);
                      ///
                      /// !!!!!!!!!!!!!!
                      /// !!! NOTICE !!! `transfer` does not return a value, in violation of the ERC-20 specification
                      /// !!!!!!!!!!!!!!
                      ///
                      /**
                        * @notice Transfer `amount` tokens from `msg.sender` to `dst`
                        * @param dst The address of the destination account
                        * @param amount The number of tokens to transfer
                        */
                      function transfer(address dst, uint256 amount) external;
                      ///
                      /// !!!!!!!!!!!!!!
                      /// !!! NOTICE !!! `transferFrom` does not return a value, in violation of the ERC-20 specification
                      /// !!!!!!!!!!!!!!
                      ///
                      /**
                        * @notice Transfer `amount` tokens from `src` to `dst`
                        * @param src The address of the source account
                        * @param dst The address of the destination account
                        * @param amount The number of tokens to transfer
                        */
                      function transferFrom(address src, address dst, uint256 amount) external;
                      /**
                        * @notice Approve `spender` to transfer up to `amount` from `src`
                        * @dev This will overwrite the approval amount for `spender`
                        *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
                        * @param spender The address of the account which may transfer tokens
                        * @param amount The number of tokens that are approved
                        * @return Whether or not the approval succeeded
                        */
                      function approve(address spender, uint256 amount) external returns (bool success);
                      /**
                        * @notice Get the current allowance from `owner` for `spender`
                        * @param owner The address of the account which owns the tokens to be spent
                        * @param spender The address of the account which may transfer tokens
                        * @return The number of tokens allowed to be spent
                        */
                      function allowance(address owner, address spender) external view returns (uint256 remaining);
                      event Transfer(address indexed from, address indexed to, uint256 amount);
                      event Approval(address indexed owner, address indexed spender, uint256 amount);
                  }
                  pragma solidity ^0.5.16;
                  contract ComptrollerErrorReporter {
                      enum Error {
                          NO_ERROR,
                          UNAUTHORIZED,
                          COMPTROLLER_MISMATCH,
                          INSUFFICIENT_SHORTFALL,
                          INSUFFICIENT_LIQUIDITY,
                          INVALID_CLOSE_FACTOR,
                          INVALID_COLLATERAL_FACTOR,
                          INVALID_LIQUIDATION_INCENTIVE,
                          MARKET_NOT_ENTERED, // no longer possible
                          MARKET_NOT_LISTED,
                          MARKET_ALREADY_LISTED,
                          MATH_ERROR,
                          NONZERO_BORROW_BALANCE,
                          PRICE_ERROR,
                          REJECTION,
                          SNAPSHOT_ERROR,
                          TOO_MANY_ASSETS,
                          TOO_MUCH_REPAY
                      }
                      enum FailureInfo {
                          ACCEPT_ADMIN_PENDING_ADMIN_CHECK,
                          ACCEPT_PENDING_IMPLEMENTATION_ADDRESS_CHECK,
                          EXIT_MARKET_BALANCE_OWED,
                          EXIT_MARKET_REJECTION,
                          SET_CLOSE_FACTOR_OWNER_CHECK,
                          SET_CLOSE_FACTOR_VALIDATION,
                          SET_COLLATERAL_FACTOR_OWNER_CHECK,
                          SET_COLLATERAL_FACTOR_NO_EXISTS,
                          SET_COLLATERAL_FACTOR_VALIDATION,
                          SET_COLLATERAL_FACTOR_WITHOUT_PRICE,
                          SET_IMPLEMENTATION_OWNER_CHECK,
                          SET_LIQUIDATION_INCENTIVE_OWNER_CHECK,
                          SET_LIQUIDATION_INCENTIVE_VALIDATION,
                          SET_MAX_ASSETS_OWNER_CHECK,
                          SET_PENDING_ADMIN_OWNER_CHECK,
                          SET_PENDING_IMPLEMENTATION_OWNER_CHECK,
                          SET_PRICE_ORACLE_OWNER_CHECK,
                          SUPPORT_MARKET_EXISTS,
                          SUPPORT_MARKET_OWNER_CHECK,
                          SET_PAUSE_GUARDIAN_OWNER_CHECK
                      }
                      /**
                        * @dev `error` corresponds to enum Error; `info` corresponds to enum FailureInfo, and `detail` is an arbitrary
                        * contract-specific code that enables us to report opaque error codes from upgradeable contracts.
                        **/
                      event Failure(uint error, uint info, uint detail);
                      /**
                        * @dev use this when reporting a known error from the money market or a non-upgradeable collaborator
                        */
                      function fail(Error err, FailureInfo info) internal returns (uint) {
                          emit Failure(uint(err), uint(info), 0);
                          return uint(err);
                      }
                      /**
                        * @dev use this when reporting an opaque error from an upgradeable collaborator contract
                        */
                      function failOpaque(Error err, FailureInfo info, uint opaqueError) internal returns (uint) {
                          emit Failure(uint(err), uint(info), opaqueError);
                          return uint(err);
                      }
                  }
                  contract TokenErrorReporter {
                      enum Error {
                          NO_ERROR,
                          UNAUTHORIZED,
                          BAD_INPUT,
                          COMPTROLLER_REJECTION,
                          COMPTROLLER_CALCULATION_ERROR,
                          INTEREST_RATE_MODEL_ERROR,
                          INVALID_ACCOUNT_PAIR,
                          INVALID_CLOSE_AMOUNT_REQUESTED,
                          INVALID_COLLATERAL_FACTOR,
                          MATH_ERROR,
                          MARKET_NOT_FRESH,
                          MARKET_NOT_LISTED,
                          TOKEN_INSUFFICIENT_ALLOWANCE,
                          TOKEN_INSUFFICIENT_BALANCE,
                          TOKEN_INSUFFICIENT_CASH,
                          TOKEN_TRANSFER_IN_FAILED,
                          TOKEN_TRANSFER_OUT_FAILED
                      }
                      /*
                       * Note: FailureInfo (but not Error) is kept in alphabetical order
                       *       This is because FailureInfo grows significantly faster, and
                       *       the order of Error has some meaning, while the order of FailureInfo
                       *       is entirely arbitrary.
                       */
                      enum FailureInfo {
                          ACCEPT_ADMIN_PENDING_ADMIN_CHECK,
                          ACCRUE_INTEREST_ACCUMULATED_INTEREST_CALCULATION_FAILED,
                          ACCRUE_INTEREST_BORROW_RATE_CALCULATION_FAILED,
                          ACCRUE_INTEREST_NEW_BORROW_INDEX_CALCULATION_FAILED,
                          ACCRUE_INTEREST_NEW_TOTAL_BORROWS_CALCULATION_FAILED,
                          ACCRUE_INTEREST_NEW_TOTAL_RESERVES_CALCULATION_FAILED,
                          ACCRUE_INTEREST_SIMPLE_INTEREST_FACTOR_CALCULATION_FAILED,
                          BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED,
                          BORROW_ACCRUE_INTEREST_FAILED,
                          BORROW_CASH_NOT_AVAILABLE,
                          BORROW_FRESHNESS_CHECK,
                          BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED,
                          BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED,
                          BORROW_MARKET_NOT_LISTED,
                          BORROW_COMPTROLLER_REJECTION,
                          LIQUIDATE_ACCRUE_BORROW_INTEREST_FAILED,
                          LIQUIDATE_ACCRUE_COLLATERAL_INTEREST_FAILED,
                          LIQUIDATE_COLLATERAL_FRESHNESS_CHECK,
                          LIQUIDATE_COMPTROLLER_REJECTION,
                          LIQUIDATE_COMPTROLLER_CALCULATE_AMOUNT_SEIZE_FAILED,
                          LIQUIDATE_CLOSE_AMOUNT_IS_UINT_MAX,
                          LIQUIDATE_CLOSE_AMOUNT_IS_ZERO,
                          LIQUIDATE_FRESHNESS_CHECK,
                          LIQUIDATE_LIQUIDATOR_IS_BORROWER,
                          LIQUIDATE_REPAY_BORROW_FRESH_FAILED,
                          LIQUIDATE_SEIZE_BALANCE_INCREMENT_FAILED,
                          LIQUIDATE_SEIZE_BALANCE_DECREMENT_FAILED,
                          LIQUIDATE_SEIZE_COMPTROLLER_REJECTION,
                          LIQUIDATE_SEIZE_LIQUIDATOR_IS_BORROWER,
                          LIQUIDATE_SEIZE_TOO_MUCH,
                          MINT_ACCRUE_INTEREST_FAILED,
                          MINT_COMPTROLLER_REJECTION,
                          MINT_EXCHANGE_CALCULATION_FAILED,
                          MINT_EXCHANGE_RATE_READ_FAILED,
                          MINT_FRESHNESS_CHECK,
                          MINT_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED,
                          MINT_NEW_TOTAL_SUPPLY_CALCULATION_FAILED,
                          MINT_TRANSFER_IN_FAILED,
                          MINT_TRANSFER_IN_NOT_POSSIBLE,
                          REDEEM_ACCRUE_INTEREST_FAILED,
                          REDEEM_COMPTROLLER_REJECTION,
                          REDEEM_EXCHANGE_TOKENS_CALCULATION_FAILED,
                          REDEEM_EXCHANGE_AMOUNT_CALCULATION_FAILED,
                          REDEEM_EXCHANGE_RATE_READ_FAILED,
                          REDEEM_FRESHNESS_CHECK,
                          REDEEM_NEW_ACCOUNT_BALANCE_CALCULATION_FAILED,
                          REDEEM_NEW_TOTAL_SUPPLY_CALCULATION_FAILED,
                          REDEEM_TRANSFER_OUT_NOT_POSSIBLE,
                          REDUCE_RESERVES_ACCRUE_INTEREST_FAILED,
                          REDUCE_RESERVES_ADMIN_CHECK,
                          REDUCE_RESERVES_CASH_NOT_AVAILABLE,
                          REDUCE_RESERVES_FRESH_CHECK,
                          REDUCE_RESERVES_VALIDATION,
                          REPAY_BEHALF_ACCRUE_INTEREST_FAILED,
                          REPAY_BORROW_ACCRUE_INTEREST_FAILED,
                          REPAY_BORROW_ACCUMULATED_BALANCE_CALCULATION_FAILED,
                          REPAY_BORROW_COMPTROLLER_REJECTION,
                          REPAY_BORROW_FRESHNESS_CHECK,
                          REPAY_BORROW_NEW_ACCOUNT_BORROW_BALANCE_CALCULATION_FAILED,
                          REPAY_BORROW_NEW_TOTAL_BALANCE_CALCULATION_FAILED,
                          REPAY_BORROW_TRANSFER_IN_NOT_POSSIBLE,
                          SET_COLLATERAL_FACTOR_OWNER_CHECK,
                          SET_COLLATERAL_FACTOR_VALIDATION,
                          SET_COMPTROLLER_OWNER_CHECK,
                          SET_INTEREST_RATE_MODEL_ACCRUE_INTEREST_FAILED,
                          SET_INTEREST_RATE_MODEL_FRESH_CHECK,
                          SET_INTEREST_RATE_MODEL_OWNER_CHECK,
                          SET_MAX_ASSETS_OWNER_CHECK,
                          SET_ORACLE_MARKET_NOT_LISTED,
                          SET_PENDING_ADMIN_OWNER_CHECK,
                          SET_RESERVE_FACTOR_ACCRUE_INTEREST_FAILED,
                          SET_RESERVE_FACTOR_ADMIN_CHECK,
                          SET_RESERVE_FACTOR_FRESH_CHECK,
                          SET_RESERVE_FACTOR_BOUNDS_CHECK,
                          TRANSFER_COMPTROLLER_REJECTION,
                          TRANSFER_NOT_ALLOWED,
                          TRANSFER_NOT_ENOUGH,
                          TRANSFER_TOO_MUCH,
                          ADD_RESERVES_ACCRUE_INTEREST_FAILED,
                          ADD_RESERVES_FRESH_CHECK,
                          ADD_RESERVES_TRANSFER_IN_NOT_POSSIBLE
                      }
                      /**
                        * @dev `error` corresponds to enum Error; `info` corresponds to enum FailureInfo, and `detail` is an arbitrary
                        * contract-specific code that enables us to report opaque error codes from upgradeable contracts.
                        **/
                      event Failure(uint error, uint info, uint detail);
                      /**
                        * @dev use this when reporting a known error from the money market or a non-upgradeable collaborator
                        */
                      function fail(Error err, FailureInfo info) internal returns (uint) {
                          emit Failure(uint(err), uint(info), 0);
                          return uint(err);
                      }
                      /**
                        * @dev use this when reporting an opaque error from an upgradeable collaborator contract
                        */
                      function failOpaque(Error err, FailureInfo info, uint opaqueError) internal returns (uint) {
                          emit Failure(uint(err), uint(info), opaqueError);
                          return uint(err);
                      }
                  }pragma solidity ^0.5.16;
                  import "./CarefulMath.sol";
                  import "./ExponentialNoError.sol";
                  /**
                   * @title Exponential module for storing fixed-precision decimals
                   * @author Compound
                   * @dev Legacy contract for compatibility reasons with existing contracts that still use MathError
                   * @notice Exp is a struct which stores decimals with a fixed precision of 18 decimal places.
                   *         Thus, if we wanted to store the 5.1, mantissa would store 5.1e18. That is:
                   *         `Exp({mantissa: 5100000000000000000})`.
                   */
                  contract Exponential is CarefulMath, ExponentialNoError {
                      /**
                       * @dev Creates an exponential from numerator and denominator values.
                       *      Note: Returns an error if (`num` * 10e18) > MAX_INT,
                       *            or if `denom` is zero.
                       */
                      function getExp(uint num, uint denom) pure internal returns (MathError, Exp memory) {
                          (MathError err0, uint scaledNumerator) = mulUInt(num, expScale);
                          if (err0 != MathError.NO_ERROR) {
                              return (err0, Exp({mantissa: 0}));
                          }
                          (MathError err1, uint rational) = divUInt(scaledNumerator, denom);
                          if (err1 != MathError.NO_ERROR) {
                              return (err1, Exp({mantissa: 0}));
                          }
                          return (MathError.NO_ERROR, Exp({mantissa: rational}));
                      }
                      /**
                       * @dev Adds two exponentials, returning a new exponential.
                       */
                      function addExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
                          (MathError error, uint result) = addUInt(a.mantissa, b.mantissa);
                          return (error, Exp({mantissa: result}));
                      }
                      /**
                       * @dev Subtracts two exponentials, returning a new exponential.
                       */
                      function subExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
                          (MathError error, uint result) = subUInt(a.mantissa, b.mantissa);
                          return (error, Exp({mantissa: result}));
                      }
                      /**
                       * @dev Multiply an Exp by a scalar, returning a new Exp.
                       */
                      function mulScalar(Exp memory a, uint scalar) pure internal returns (MathError, Exp memory) {
                          (MathError err0, uint scaledMantissa) = mulUInt(a.mantissa, scalar);
                          if (err0 != MathError.NO_ERROR) {
                              return (err0, Exp({mantissa: 0}));
                          }
                          return (MathError.NO_ERROR, Exp({mantissa: scaledMantissa}));
                      }
                      /**
                       * @dev Multiply an Exp by a scalar, then truncate to return an unsigned integer.
                       */
                      function mulScalarTruncate(Exp memory a, uint scalar) pure internal returns (MathError, uint) {
                          (MathError err, Exp memory product) = mulScalar(a, scalar);
                          if (err != MathError.NO_ERROR) {
                              return (err, 0);
                          }
                          return (MathError.NO_ERROR, truncate(product));
                      }
                      /**
                       * @dev Multiply an Exp by a scalar, truncate, then add an to an unsigned integer, returning an unsigned integer.
                       */
                      function mulScalarTruncateAddUInt(Exp memory a, uint scalar, uint addend) pure internal returns (MathError, uint) {
                          (MathError err, Exp memory product) = mulScalar(a, scalar);
                          if (err != MathError.NO_ERROR) {
                              return (err, 0);
                          }
                          return addUInt(truncate(product), addend);
                      }
                      /**
                       * @dev Divide an Exp by a scalar, returning a new Exp.
                       */
                      function divScalar(Exp memory a, uint scalar) pure internal returns (MathError, Exp memory) {
                          (MathError err0, uint descaledMantissa) = divUInt(a.mantissa, scalar);
                          if (err0 != MathError.NO_ERROR) {
                              return (err0, Exp({mantissa: 0}));
                          }
                          return (MathError.NO_ERROR, Exp({mantissa: descaledMantissa}));
                      }
                      /**
                       * @dev Divide a scalar by an Exp, returning a new Exp.
                       */
                      function divScalarByExp(uint scalar, Exp memory divisor) pure internal returns (MathError, Exp memory) {
                          /*
                            We are doing this as:
                            getExp(mulUInt(expScale, scalar), divisor.mantissa)
                            How it works:
                            Exp = a / b;
                            Scalar = s;
                            `s / (a / b)` = `b * s / a` and since for an Exp `a = mantissa, b = expScale`
                          */
                          (MathError err0, uint numerator) = mulUInt(expScale, scalar);
                          if (err0 != MathError.NO_ERROR) {
                              return (err0, Exp({mantissa: 0}));
                          }
                          return getExp(numerator, divisor.mantissa);
                      }
                      /**
                       * @dev Divide a scalar by an Exp, then truncate to return an unsigned integer.
                       */
                      function divScalarByExpTruncate(uint scalar, Exp memory divisor) pure internal returns (MathError, uint) {
                          (MathError err, Exp memory fraction) = divScalarByExp(scalar, divisor);
                          if (err != MathError.NO_ERROR) {
                              return (err, 0);
                          }
                          return (MathError.NO_ERROR, truncate(fraction));
                      }
                      /**
                       * @dev Multiplies two exponentials, returning a new exponential.
                       */
                      function mulExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
                          (MathError err0, uint doubleScaledProduct) = mulUInt(a.mantissa, b.mantissa);
                          if (err0 != MathError.NO_ERROR) {
                              return (err0, Exp({mantissa: 0}));
                          }
                          // We add half the scale before dividing so that we get rounding instead of truncation.
                          //  See "Listing 6" and text above it at https://accu.org/index.php/journals/1717
                          // Without this change, a result like 6.6...e-19 will be truncated to 0 instead of being rounded to 1e-18.
                          (MathError err1, uint doubleScaledProductWithHalfScale) = addUInt(halfExpScale, doubleScaledProduct);
                          if (err1 != MathError.NO_ERROR) {
                              return (err1, Exp({mantissa: 0}));
                          }
                          (MathError err2, uint product) = divUInt(doubleScaledProductWithHalfScale, expScale);
                          // The only error `div` can return is MathError.DIVISION_BY_ZERO but we control `expScale` and it is not zero.
                          assert(err2 == MathError.NO_ERROR);
                          return (MathError.NO_ERROR, Exp({mantissa: product}));
                      }
                      /**
                       * @dev Multiplies two exponentials given their mantissas, returning a new exponential.
                       */
                      function mulExp(uint a, uint b) pure internal returns (MathError, Exp memory) {
                          return mulExp(Exp({mantissa: a}), Exp({mantissa: b}));
                      }
                      /**
                       * @dev Multiplies three exponentials, returning a new exponential.
                       */
                      function mulExp3(Exp memory a, Exp memory b, Exp memory c) pure internal returns (MathError, Exp memory) {
                          (MathError err, Exp memory ab) = mulExp(a, b);
                          if (err != MathError.NO_ERROR) {
                              return (err, ab);
                          }
                          return mulExp(ab, c);
                      }
                      /**
                       * @dev Divides two exponentials, returning a new exponential.
                       *     (a/scale) / (b/scale) = (a/scale) * (scale/b) = a/b,
                       *  which we can scale as an Exp by calling getExp(a.mantissa, b.mantissa)
                       */
                      function divExp(Exp memory a, Exp memory b) pure internal returns (MathError, Exp memory) {
                          return getExp(a.mantissa, b.mantissa);
                      }
                  }
                  pragma solidity ^0.5.16;
                  /**
                   * @title Exponential module for storing fixed-precision decimals
                   * @author Compound
                   * @notice Exp is a struct which stores decimals with a fixed precision of 18 decimal places.
                   *         Thus, if we wanted to store the 5.1, mantissa would store 5.1e18. That is:
                   *         `Exp({mantissa: 5100000000000000000})`.
                   */
                  contract ExponentialNoError {
                      uint constant expScale = 1e18;
                      uint constant doubleScale = 1e36;
                      uint constant halfExpScale = expScale/2;
                      uint constant mantissaOne = expScale;
                      struct Exp {
                          uint mantissa;
                      }
                      struct Double {
                          uint mantissa;
                      }
                      /**
                       * @dev Truncates the given exp to a whole number value.
                       *      For example, truncate(Exp{mantissa: 15 * expScale}) = 15
                       */
                      function truncate(Exp memory exp) pure internal returns (uint) {
                          // Note: We are not using careful math here as we're performing a division that cannot fail
                          return exp.mantissa / expScale;
                      }
                      /**
                       * @dev Multiply an Exp by a scalar, then truncate to return an unsigned integer.
                       */
                      function mul_ScalarTruncate(Exp memory a, uint scalar) pure internal returns (uint) {
                          Exp memory product = mul_(a, scalar);
                          return truncate(product);
                      }
                      /**
                       * @dev Multiply an Exp by a scalar, truncate, then add an to an unsigned integer, returning an unsigned integer.
                       */
                      function mul_ScalarTruncateAddUInt(Exp memory a, uint scalar, uint addend) pure internal returns (uint) {
                          Exp memory product = mul_(a, scalar);
                          return add_(truncate(product), addend);
                      }
                      /**
                       * @dev Checks if first Exp is less than second Exp.
                       */
                      function lessThanExp(Exp memory left, Exp memory right) pure internal returns (bool) {
                          return left.mantissa < right.mantissa;
                      }
                      /**
                       * @dev Checks if left Exp <= right Exp.
                       */
                      function lessThanOrEqualExp(Exp memory left, Exp memory right) pure internal returns (bool) {
                          return left.mantissa <= right.mantissa;
                      }
                      /**
                       * @dev Checks if left Exp > right Exp.
                       */
                      function greaterThanExp(Exp memory left, Exp memory right) pure internal returns (bool) {
                          return left.mantissa > right.mantissa;
                      }
                      /**
                       * @dev returns true if Exp is exactly zero
                       */
                      function isZeroExp(Exp memory value) pure internal returns (bool) {
                          return value.mantissa == 0;
                      }
                      function safe224(uint n, string memory errorMessage) pure internal returns (uint224) {
                          require(n < 2**224, errorMessage);
                          return uint224(n);
                      }
                      function safe32(uint n, string memory errorMessage) pure internal returns (uint32) {
                          require(n < 2**32, errorMessage);
                          return uint32(n);
                      }
                      function add_(Exp memory a, Exp memory b) pure internal returns (Exp memory) {
                          return Exp({mantissa: add_(a.mantissa, b.mantissa)});
                      }
                      function add_(Double memory a, Double memory b) pure internal returns (Double memory) {
                          return Double({mantissa: add_(a.mantissa, b.mantissa)});
                      }
                      function add_(uint a, uint b) pure internal returns (uint) {
                          return add_(a, b, "addition overflow");
                      }
                      function add_(uint a, uint b, string memory errorMessage) pure internal returns (uint) {
                          uint c = a + b;
                          require(c >= a, errorMessage);
                          return c;
                      }
                      function sub_(Exp memory a, Exp memory b) pure internal returns (Exp memory) {
                          return Exp({mantissa: sub_(a.mantissa, b.mantissa)});
                      }
                      function sub_(Double memory a, Double memory b) pure internal returns (Double memory) {
                          return Double({mantissa: sub_(a.mantissa, b.mantissa)});
                      }
                      function sub_(uint a, uint b) pure internal returns (uint) {
                          return sub_(a, b, "subtraction underflow");
                      }
                      function sub_(uint a, uint b, string memory errorMessage) pure internal returns (uint) {
                          require(b <= a, errorMessage);
                          return a - b;
                      }
                      function mul_(Exp memory a, Exp memory b) pure internal returns (Exp memory) {
                          return Exp({mantissa: mul_(a.mantissa, b.mantissa) / expScale});
                      }
                      function mul_(Exp memory a, uint b) pure internal returns (Exp memory) {
                          return Exp({mantissa: mul_(a.mantissa, b)});
                      }
                      function mul_(uint a, Exp memory b) pure internal returns (uint) {
                          return mul_(a, b.mantissa) / expScale;
                      }
                      function mul_(Double memory a, Double memory b) pure internal returns (Double memory) {
                          return Double({mantissa: mul_(a.mantissa, b.mantissa) / doubleScale});
                      }
                      function mul_(Double memory a, uint b) pure internal returns (Double memory) {
                          return Double({mantissa: mul_(a.mantissa, b)});
                      }
                      function mul_(uint a, Double memory b) pure internal returns (uint) {
                          return mul_(a, b.mantissa) / doubleScale;
                      }
                      function mul_(uint a, uint b) pure internal returns (uint) {
                          return mul_(a, b, "multiplication overflow");
                      }
                      function mul_(uint a, uint b, string memory errorMessage) pure internal returns (uint) {
                          if (a == 0 || b == 0) {
                              return 0;
                          }
                          uint c = a * b;
                          require(c / a == b, errorMessage);
                          return c;
                      }
                      function div_(Exp memory a, Exp memory b) pure internal returns (Exp memory) {
                          return Exp({mantissa: div_(mul_(a.mantissa, expScale), b.mantissa)});
                      }
                      function div_(Exp memory a, uint b) pure internal returns (Exp memory) {
                          return Exp({mantissa: div_(a.mantissa, b)});
                      }
                      function div_(uint a, Exp memory b) pure internal returns (uint) {
                          return div_(mul_(a, expScale), b.mantissa);
                      }
                      function div_(Double memory a, Double memory b) pure internal returns (Double memory) {
                          return Double({mantissa: div_(mul_(a.mantissa, doubleScale), b.mantissa)});
                      }
                      function div_(Double memory a, uint b) pure internal returns (Double memory) {
                          return Double({mantissa: div_(a.mantissa, b)});
                      }
                      function div_(uint a, Double memory b) pure internal returns (uint) {
                          return div_(mul_(a, doubleScale), b.mantissa);
                      }
                      function div_(uint a, uint b) pure internal returns (uint) {
                          return div_(a, b, "divide by zero");
                      }
                      function div_(uint a, uint b, string memory errorMessage) pure internal returns (uint) {
                          require(b > 0, errorMessage);
                          return a / b;
                      }
                      function fraction(uint a, uint b) pure internal returns (Double memory) {
                          return Double({mantissa: div_(mul_(a, doubleScale), b)});
                      }
                  }
                  pragma solidity ^0.5.16;
                  pragma experimental ABIEncoderV2;
                  contract Comp {
                      /// @notice EIP-20 token name for this token
                      string public constant name = "Compound";
                      /// @notice EIP-20 token symbol for this token
                      string public constant symbol = "COMP";
                      /// @notice EIP-20 token decimals for this token
                      uint8 public constant decimals = 18;
                      /// @notice Total number of tokens in circulation
                      uint public constant totalSupply = 10000000e18; // 10 million Comp
                      /// @notice Allowance amounts on behalf of others
                      mapping (address => mapping (address => uint96)) internal allowances;
                      /// @notice Official record of token balances for each account
                      mapping (address => uint96) internal balances;
                      /// @notice A record of each accounts delegate
                      mapping (address => address) public delegates;
                      /// @notice A checkpoint for marking number of votes from a given block
                      struct Checkpoint {
                          uint32 fromBlock;
                          uint96 votes;
                      }
                      /// @notice A record of votes checkpoints for each account, by index
                      mapping (address => mapping (uint32 => Checkpoint)) public checkpoints;
                      /// @notice The number of checkpoints for each account
                      mapping (address => uint32) public numCheckpoints;
                      /// @notice The EIP-712 typehash for the contract's domain
                      bytes32 public constant DOMAIN_TYPEHASH = keccak256("EIP712Domain(string name,uint256 chainId,address verifyingContract)");
                      /// @notice The EIP-712 typehash for the delegation struct used by the contract
                      bytes32 public constant DELEGATION_TYPEHASH = keccak256("Delegation(address delegatee,uint256 nonce,uint256 expiry)");
                      /// @notice A record of states for signing / validating signatures
                      mapping (address => uint) public nonces;
                      /// @notice An event thats emitted when an account changes its delegate
                      event DelegateChanged(address indexed delegator, address indexed fromDelegate, address indexed toDelegate);
                      /// @notice An event thats emitted when a delegate account's vote balance changes
                      event DelegateVotesChanged(address indexed delegate, uint previousBalance, uint newBalance);
                      /// @notice The standard EIP-20 transfer event
                      event Transfer(address indexed from, address indexed to, uint256 amount);
                      /// @notice The standard EIP-20 approval event
                      event Approval(address indexed owner, address indexed spender, uint256 amount);
                      /**
                       * @notice Construct a new Comp token
                       * @param account The initial account to grant all the tokens
                       */
                      constructor(address account) public {
                          balances[account] = uint96(totalSupply);
                          emit Transfer(address(0), account, totalSupply);
                      }
                      /**
                       * @notice Get the number of tokens `spender` is approved to spend on behalf of `account`
                       * @param account The address of the account holding the funds
                       * @param spender The address of the account spending the funds
                       * @return The number of tokens approved
                       */
                      function allowance(address account, address spender) external view returns (uint) {
                          return allowances[account][spender];
                      }
                      /**
                       * @notice Approve `spender` to transfer up to `amount` from `src`
                       * @dev This will overwrite the approval amount for `spender`
                       *  and is subject to issues noted [here](https://eips.ethereum.org/EIPS/eip-20#approve)
                       * @param spender The address of the account which may transfer tokens
                       * @param rawAmount The number of tokens that are approved (2^256-1 means infinite)
                       * @return Whether or not the approval succeeded
                       */
                      function approve(address spender, uint rawAmount) external returns (bool) {
                          uint96 amount;
                          if (rawAmount == uint(-1)) {
                              amount = uint96(-1);
                          } else {
                              amount = safe96(rawAmount, "Comp::approve: amount exceeds 96 bits");
                          }
                          allowances[msg.sender][spender] = amount;
                          emit Approval(msg.sender, spender, amount);
                          return true;
                      }
                      /**
                       * @notice Get the number of tokens held by the `account`
                       * @param account The address of the account to get the balance of
                       * @return The number of tokens held
                       */
                      function balanceOf(address account) external view returns (uint) {
                          return balances[account];
                      }
                      /**
                       * @notice Transfer `amount` tokens from `msg.sender` to `dst`
                       * @param dst The address of the destination account
                       * @param rawAmount The number of tokens to transfer
                       * @return Whether or not the transfer succeeded
                       */
                      function transfer(address dst, uint rawAmount) external returns (bool) {
                          uint96 amount = safe96(rawAmount, "Comp::transfer: amount exceeds 96 bits");
                          _transferTokens(msg.sender, dst, amount);
                          return true;
                      }
                      /**
                       * @notice Transfer `amount` tokens from `src` to `dst`
                       * @param src The address of the source account
                       * @param dst The address of the destination account
                       * @param rawAmount The number of tokens to transfer
                       * @return Whether or not the transfer succeeded
                       */
                      function transferFrom(address src, address dst, uint rawAmount) external returns (bool) {
                          address spender = msg.sender;
                          uint96 spenderAllowance = allowances[src][spender];
                          uint96 amount = safe96(rawAmount, "Comp::approve: amount exceeds 96 bits");
                          if (spender != src && spenderAllowance != uint96(-1)) {
                              uint96 newAllowance = sub96(spenderAllowance, amount, "Comp::transferFrom: transfer amount exceeds spender allowance");
                              allowances[src][spender] = newAllowance;
                              emit Approval(src, spender, newAllowance);
                          }
                          _transferTokens(src, dst, amount);
                          return true;
                      }
                      /**
                       * @notice Delegate votes from `msg.sender` to `delegatee`
                       * @param delegatee The address to delegate votes to
                       */
                      function delegate(address delegatee) public {
                          return _delegate(msg.sender, delegatee);
                      }
                      /**
                       * @notice Delegates votes from signatory to `delegatee`
                       * @param delegatee The address to delegate votes to
                       * @param nonce The contract state required to match the signature
                       * @param expiry The time at which to expire the signature
                       * @param v The recovery byte of the signature
                       * @param r Half of the ECDSA signature pair
                       * @param s Half of the ECDSA signature pair
                       */
                      function delegateBySig(address delegatee, uint nonce, uint expiry, uint8 v, bytes32 r, bytes32 s) public {
                          bytes32 domainSeparator = keccak256(abi.encode(DOMAIN_TYPEHASH, keccak256(bytes(name)), getChainId(), address(this)));
                          bytes32 structHash = keccak256(abi.encode(DELEGATION_TYPEHASH, delegatee, nonce, expiry));
                          bytes32 digest = keccak256(abi.encodePacked("\\x19\\x01", domainSeparator, structHash));
                          address signatory = ecrecover(digest, v, r, s);
                          require(signatory != address(0), "Comp::delegateBySig: invalid signature");
                          require(nonce == nonces[signatory]++, "Comp::delegateBySig: invalid nonce");
                          require(now <= expiry, "Comp::delegateBySig: signature expired");
                          return _delegate(signatory, delegatee);
                      }
                      /**
                       * @notice Gets the current votes balance for `account`
                       * @param account The address to get votes balance
                       * @return The number of current votes for `account`
                       */
                      function getCurrentVotes(address account) external view returns (uint96) {
                          uint32 nCheckpoints = numCheckpoints[account];
                          return nCheckpoints > 0 ? checkpoints[account][nCheckpoints - 1].votes : 0;
                      }
                      /**
                       * @notice Determine the prior number of votes for an account as of a block number
                       * @dev Block number must be a finalized block or else this function will revert to prevent misinformation.
                       * @param account The address of the account to check
                       * @param blockNumber The block number to get the vote balance at
                       * @return The number of votes the account had as of the given block
                       */
                      function getPriorVotes(address account, uint blockNumber) public view returns (uint96) {
                          require(blockNumber < block.number, "Comp::getPriorVotes: not yet determined");
                          uint32 nCheckpoints = numCheckpoints[account];
                          if (nCheckpoints == 0) {
                              return 0;
                          }
                          // First check most recent balance
                          if (checkpoints[account][nCheckpoints - 1].fromBlock <= blockNumber) {
                              return checkpoints[account][nCheckpoints - 1].votes;
                          }
                          // Next check implicit zero balance
                          if (checkpoints[account][0].fromBlock > blockNumber) {
                              return 0;
                          }
                          uint32 lower = 0;
                          uint32 upper = nCheckpoints - 1;
                          while (upper > lower) {
                              uint32 center = upper - (upper - lower) / 2; // ceil, avoiding overflow
                              Checkpoint memory cp = checkpoints[account][center];
                              if (cp.fromBlock == blockNumber) {
                                  return cp.votes;
                              } else if (cp.fromBlock < blockNumber) {
                                  lower = center;
                              } else {
                                  upper = center - 1;
                              }
                          }
                          return checkpoints[account][lower].votes;
                      }
                      function _delegate(address delegator, address delegatee) internal {
                          address currentDelegate = delegates[delegator];
                          uint96 delegatorBalance = balances[delegator];
                          delegates[delegator] = delegatee;
                          emit DelegateChanged(delegator, currentDelegate, delegatee);
                          _moveDelegates(currentDelegate, delegatee, delegatorBalance);
                      }
                      function _transferTokens(address src, address dst, uint96 amount) internal {
                          require(src != address(0), "Comp::_transferTokens: cannot transfer from the zero address");
                          require(dst != address(0), "Comp::_transferTokens: cannot transfer to the zero address");
                          balances[src] = sub96(balances[src], amount, "Comp::_transferTokens: transfer amount exceeds balance");
                          balances[dst] = add96(balances[dst], amount, "Comp::_transferTokens: transfer amount overflows");
                          emit Transfer(src, dst, amount);
                          _moveDelegates(delegates[src], delegates[dst], amount);
                      }
                      function _moveDelegates(address srcRep, address dstRep, uint96 amount) internal {
                          if (srcRep != dstRep && amount > 0) {
                              if (srcRep != address(0)) {
                                  uint32 srcRepNum = numCheckpoints[srcRep];
                                  uint96 srcRepOld = srcRepNum > 0 ? checkpoints[srcRep][srcRepNum - 1].votes : 0;
                                  uint96 srcRepNew = sub96(srcRepOld, amount, "Comp::_moveVotes: vote amount underflows");
                                  _writeCheckpoint(srcRep, srcRepNum, srcRepOld, srcRepNew);
                              }
                              if (dstRep != address(0)) {
                                  uint32 dstRepNum = numCheckpoints[dstRep];
                                  uint96 dstRepOld = dstRepNum > 0 ? checkpoints[dstRep][dstRepNum - 1].votes : 0;
                                  uint96 dstRepNew = add96(dstRepOld, amount, "Comp::_moveVotes: vote amount overflows");
                                  _writeCheckpoint(dstRep, dstRepNum, dstRepOld, dstRepNew);
                              }
                          }
                      }
                      function _writeCheckpoint(address delegatee, uint32 nCheckpoints, uint96 oldVotes, uint96 newVotes) internal {
                        uint32 blockNumber = safe32(block.number, "Comp::_writeCheckpoint: block number exceeds 32 bits");
                        if (nCheckpoints > 0 && checkpoints[delegatee][nCheckpoints - 1].fromBlock == blockNumber) {
                            checkpoints[delegatee][nCheckpoints - 1].votes = newVotes;
                        } else {
                            checkpoints[delegatee][nCheckpoints] = Checkpoint(blockNumber, newVotes);
                            numCheckpoints[delegatee] = nCheckpoints + 1;
                        }
                        emit DelegateVotesChanged(delegatee, oldVotes, newVotes);
                      }
                      function safe32(uint n, string memory errorMessage) internal pure returns (uint32) {
                          require(n < 2**32, errorMessage);
                          return uint32(n);
                      }
                      function safe96(uint n, string memory errorMessage) internal pure returns (uint96) {
                          require(n < 2**96, errorMessage);
                          return uint96(n);
                      }
                      function add96(uint96 a, uint96 b, string memory errorMessage) internal pure returns (uint96) {
                          uint96 c = a + b;
                          require(c >= a, errorMessage);
                          return c;
                      }
                      function sub96(uint96 a, uint96 b, string memory errorMessage) internal pure returns (uint96) {
                          require(b <= a, errorMessage);
                          return a - b;
                      }
                      function getChainId() internal pure returns (uint) {
                          uint256 chainId;
                          assembly { chainId := chainid() }
                          return chainId;
                      }
                  }
                  pragma solidity ^0.5.16;
                  /**
                    * @title Compound's InterestRateModel Interface
                    * @author Compound
                    */
                  contract InterestRateModel {
                      /// @notice Indicator that this is an InterestRateModel contract (for inspection)
                      bool public constant isInterestRateModel = true;
                      /**
                        * @notice Calculates the current borrow interest rate per block
                        * @param cash The total amount of cash the market has
                        * @param borrows The total amount of borrows the market has outstanding
                        * @param reserves The total amount of reserves the market has
                        * @return The borrow rate per block (as a percentage, and scaled by 1e18)
                        */
                      function getBorrowRate(uint cash, uint borrows, uint reserves) external view returns (uint);
                      /**
                        * @notice Calculates the current supply interest rate per block
                        * @param cash The total amount of cash the market has
                        * @param borrows The total amount of borrows the market has outstanding
                        * @param reserves The total amount of reserves the market has
                        * @param reserveFactorMantissa The current reserve factor the market has
                        * @return The supply rate per block (as a percentage, and scaled by 1e18)
                        */
                      function getSupplyRate(uint cash, uint borrows, uint reserves, uint reserveFactorMantissa) external view returns (uint);
                  }
                  pragma solidity ^0.5.16;
                  import "./CToken.sol";
                  contract PriceOracle {
                      /// @notice Indicator that this is a PriceOracle contract (for inspection)
                      bool public constant isPriceOracle = true;
                      /**
                        * @notice Get the underlying price of a cToken asset
                        * @param cToken The cToken to get the underlying price of
                        * @return The underlying asset price mantissa (scaled by 1e18).
                        *  Zero means the price is unavailable.
                        */
                      function getUnderlyingPrice(CToken cToken) external view returns (uint);
                  }
                  pragma solidity ^0.5.16;
                  import "./ErrorReporter.sol";
                  import "./ComptrollerStorage.sol";
                  /**
                   * @title ComptrollerCore
                   * @dev Storage for the comptroller is at this address, while execution is delegated to the `comptrollerImplementation`.
                   * CTokens should reference this contract as their comptroller.
                   */
                  contract Unitroller is UnitrollerAdminStorage, ComptrollerErrorReporter {
                      /**
                        * @notice Emitted when pendingComptrollerImplementation is changed
                        */
                      event NewPendingImplementation(address oldPendingImplementation, address newPendingImplementation);
                      /**
                        * @notice Emitted when pendingComptrollerImplementation is accepted, which means comptroller implementation is updated
                        */
                      event NewImplementation(address oldImplementation, address newImplementation);
                      /**
                        * @notice Emitted when pendingAdmin is changed
                        */
                      event NewPendingAdmin(address oldPendingAdmin, address newPendingAdmin);
                      /**
                        * @notice Emitted when pendingAdmin is accepted, which means admin is updated
                        */
                      event NewAdmin(address oldAdmin, address newAdmin);
                      constructor() public {
                          // Set admin to caller
                          admin = msg.sender;
                      }
                      /*** Admin Functions ***/
                      function _setPendingImplementation(address newPendingImplementation) public returns (uint) {
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_PENDING_IMPLEMENTATION_OWNER_CHECK);
                          }
                          address oldPendingImplementation = pendingComptrollerImplementation;
                          pendingComptrollerImplementation = newPendingImplementation;
                          emit NewPendingImplementation(oldPendingImplementation, pendingComptrollerImplementation);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                      * @notice Accepts new implementation of comptroller. msg.sender must be pendingImplementation
                      * @dev Admin function for new implementation to accept it's role as implementation
                      * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                      */
                      function _acceptImplementation() public returns (uint) {
                          // Check caller is pendingImplementation and pendingImplementation ≠ address(0)
                          if (msg.sender != pendingComptrollerImplementation || pendingComptrollerImplementation == address(0)) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.ACCEPT_PENDING_IMPLEMENTATION_ADDRESS_CHECK);
                          }
                          // Save current values for inclusion in log
                          address oldImplementation = comptrollerImplementation;
                          address oldPendingImplementation = pendingComptrollerImplementation;
                          comptrollerImplementation = pendingComptrollerImplementation;
                          pendingComptrollerImplementation = address(0);
                          emit NewImplementation(oldImplementation, comptrollerImplementation);
                          emit NewPendingImplementation(oldPendingImplementation, pendingComptrollerImplementation);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                        * @notice Begins transfer of admin rights. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
                        * @dev Admin function to begin change of admin. The newPendingAdmin must call `_acceptAdmin` to finalize the transfer.
                        * @param newPendingAdmin New pending admin.
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function _setPendingAdmin(address newPendingAdmin) public returns (uint) {
                          // Check caller = admin
                          if (msg.sender != admin) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.SET_PENDING_ADMIN_OWNER_CHECK);
                          }
                          // Save current value, if any, for inclusion in log
                          address oldPendingAdmin = pendingAdmin;
                          // Store pendingAdmin with value newPendingAdmin
                          pendingAdmin = newPendingAdmin;
                          // Emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin)
                          emit NewPendingAdmin(oldPendingAdmin, newPendingAdmin);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                        * @notice Accepts transfer of admin rights. msg.sender must be pendingAdmin
                        * @dev Admin function for pending admin to accept role and update admin
                        * @return uint 0=success, otherwise a failure (see ErrorReporter.sol for details)
                        */
                      function _acceptAdmin() public returns (uint) {
                          // Check caller is pendingAdmin and pendingAdmin ≠ address(0)
                          if (msg.sender != pendingAdmin || msg.sender == address(0)) {
                              return fail(Error.UNAUTHORIZED, FailureInfo.ACCEPT_ADMIN_PENDING_ADMIN_CHECK);
                          }
                          // Save current values for inclusion in log
                          address oldAdmin = admin;
                          address oldPendingAdmin = pendingAdmin;
                          // Store admin with value pendingAdmin
                          admin = pendingAdmin;
                          // Clear the pending value
                          pendingAdmin = address(0);
                          emit NewAdmin(oldAdmin, admin);
                          emit NewPendingAdmin(oldPendingAdmin, pendingAdmin);
                          return uint(Error.NO_ERROR);
                      }
                      /**
                       * @dev Delegates execution to an implementation contract.
                       * It returns to the external caller whatever the implementation returns
                       * or forwards reverts.
                       */
                      function () payable external {
                          // delegate all other functions to current implementation
                          (bool success, ) = comptrollerImplementation.delegatecall(msg.data);
                          assembly {
                                let free_mem_ptr := mload(0x40)
                                returndatacopy(free_mem_ptr, 0, returndatasize)
                                switch success
                                case 0 { revert(free_mem_ptr, returndatasize) }
                                default { return(free_mem_ptr, returndatasize) }
                          }
                      }
                  }