def bytes(cls):
        """
        Bytes which are expected when encoding an instance constructed using
        C{kwargs} and which are expected to result in an identical instance when
        decoded.

        @return: The L{bytes} of a wire encoded message.
        """
        return (
            b'\x00\x00'
            b'\x00'
            b'\x0c' # RA: 0, Z, RCODE: 12
            b'\x00\x00'
            b'\x00\x00'
            b'\x00\x00'
            b'\x00\x01' # 1 additionals

            # Additional OPT record
            b'\x00'
            b'\x00\x29'
            b'\x10\x00'
            b'\xab' # Extended RCODE: 171
            b'\x00'
            b'\x00\x00'
            b'\x00\x00'
        )

        Bytes which are expected when encoding an instance constructed using
        C{kwargs} and which are expected to result in an identical instance when
        decoded.

        @return: The L{bytes} of a wire encoded message.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/names/test/test_dns.py