def toString(self):
        """
        Implement L{IKnownHostEntry.toString} by recording the comma-separated
        hostnames, key type, and base-64 encoded key.

        @return: The string representation of this entry, with unhashed hostname
            information.
        @rtype: L{bytes}
        """
        fields = [b','.join(self._hostnames),
                  self.keyType,
                  _b64encode(self.publicKey.blob())]
        if self.comment is not None:
            fields.append(self.comment)
        return b' '.join(fields)

        Implement L{IKnownHostEntry.toString} by recording the comma-separated
        hostnames, key type, and base-64 encoded key.

        @return: The string representation of this entry, with unhashed hostname
            information.
        @rtype: L{bytes}
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/client/knownhosts.py