code: def list_queues(self):
          
          lines = output_lines(
              self.exec_rabbitmqctl_list('queues', ['-p', self.vhost]))
          return [tuple(line.split(None, 1)) for line in lines]
docs: Run the ``list_queues`` command (for the default vhost) and return a
          list of tuples describing the queues.
  
          :return:
              A list of 2-element tuples. The first element is the queue name,
              the second is the current queue size.