code: def read(self, count=None, block=None, consumer=None):
          
          if consumer is None: consumer = self._consumer
          return self.database.xreadgroup(self.name, consumer, self._read_keys,
                                          count, block)
docs: Read unseen messages from all streams in the consumer group. Wrapper
          for :py:class:`Database.xreadgroup` method.
  
          :param int count: limit number of messages returned
          :param int block: milliseconds to block, 0 for indefinitely.
          :param consumer: consumer name
          :returns: a list of (stream key, messages) tuples, where messages is
              a list of (message id, data) 2-tuples.