code: def _process_queue(self):
          '''
          If there are any message in the queue, process one of them.
          '''
          if len(self._queue):
              args, kwargs = self._queue.popleft()
              self.publish(*args, **kwargsf _process_queue(self):
          '''
          If there are any message in the queue, process one of them.
          '''
          if len(self._queue):
              args, kwargs = self._queue.popleft()
              self.publish(*args, **kwargs)
docs: If there are any message in the queue, process one of them.