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'\x01\x00' # ID: 256
            b'\x04' # QR: 0, OPCODE: 0, AA: 1, TC: 0, RD: 0
            b'\x00' # RA: 0, Z, RCODE: 0
            b'\x00\x00' # Query count
            b'\x00\x01' # Answer count
            b'\x00\x00' # Authorities count
            b'\x00\x00' # Additionals count
            # Answer
            b'\x00' # RR NAME (root)
            b'\x00\x01' # RR TYPE 1 (A)
            b'\x00\x01' # RR CLASS 1 (IN)
            b'\x00\x00\x00\x00' # RR TTL
            b'\x00\x04' # RDLENGTH 4
            b'\x01\x02\x03\x04' # IPv4 1.2.3.4
        )

        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