code: def _publisher_callback(self, publish_ack):
          
          logging.debug("ack received: " + str(publish_ack).replace('\n', ' '))
          self._rx_queue.append(publish_ack)
docs: publisher callback that grpc and web socket can pass messages to
          address the received message onto the queue
          :param publish_ack: EventHub_pb2.Ack the ack received from either wss or grpc
          :return: None