code: def consume(self, no_ack=None):
          
          no_ack = no_ack or self.no_ack
          self.backend.declare_consumer(queue=self.queue, no_ack=no_ack,
                                        callback=self._receive_callback,
                                        consumer_tag=self.consumer_tag,
                                        nowait=True)
          self.channel_open = True
docs: Declare consumer.