def decode(self, strio, length=None):
        """
        Load the bytes which are part of this record from the stream and store
        them unparsed and unmodified.
        """
        if length is None:
            raise Exception('must know length for unknown record types')
        self.data = readPrecisely(strio, length)

        Load the bytes which are part of this record from the stream and store
        them unparsed and unmodified.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/names/dns.py