    function checkSuccess(
    )
        private
        pure
        returns (bool)
    {
        uint256 returnValue = 0;
        assembly {
            switch returndatasize
            case 0x0 {
                returnValue := 1
            }
            case 0x20 {
                returndatacopy(0x0, 0x0, 0x20)
                returnValue := mload(0x0)
            }
            default { }
        }
        return returnValue != 0;
    }