code: def pattern(self, pattern):
          
          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)]
docs: Create a pattern channel.
  
          Returns ``_Sender`` object implementing
          :class:`~aioredis.abc.AbcChannel`.