def pattern(self, pattern):
        """Create a pattern channel.

        Returns ``_Sender`` object implementing
        :class:`~aioredis.abc.AbcChannel`.
        """
        enc_pattern = _converters[type(pattern)](pattern)
        if (enc_pattern, True) not in self._refs:
            ch = _Sender(self, enc_pattern,
                         is_pattern=True)
            self._refs[(enc_pattern, True)] = ch
        return self._refs[(enc_pattern, True)]