library AddressUtils {
    /**
     * @dev Returns whether the target address is a contract.
     * @param _addr Address to check.
     * @return addressCheck True if _addr is a contract, false if not.
     */
    function isContract(address _addr)
        internal
        view
        returns (bool addressCheck)
    {
        // This method relies in extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        assembly {
            codehash := extcodehash(_addr)
        } // solhint-disable-line
        addressCheck = (codehash != 0x0 && codehash != accountHash);
    }
}
/**
 * @notice Based on:
 * https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/utils/Address.sol
 * Requires EIP-1052.
 * @dev Utility library of inline functions on addresses.
 */
function isContract(address _addr)
        internal
        view
        returns (bool addressCheck)
    {
        // This method relies in extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        // According to EIP-1052, 0x0 is the value returned for not-yet created accounts
        // and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
        // for accounts without code, i.e. `keccak256('')`
        bytes32 codehash;
        bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
        assembly {
            codehash := extcodehash(_addr)
        } // solhint-disable-line
        addressCheck = (codehash != 0x0 && codehash != accountHash);
    }
/**
 * @dev Returns whether the target address is a contract.
 * @param _addr Address to check.
 * @return addressCheck True if _addr is a contract, false if not.
 */