code: def declare_queue(self, queue_name):
          
          if queue_name not in self.queues:
              self.emit_before("declare_queue", queue_name)
              self.queues[queue_name] = Queue()
              self.emit_after("declare_queue", queue_name)
  
              delayed_name = dq_name(queue_name)
              self.queues[delayed_name] = Queue()
              self.delay_queues.add(delayed_name)
              self.emit_after("declare_delay_queue", delayed_name)
docs: Declare a queue.  Has no effect if a queue with the given
          name has already been declared.
  
          Parameters:
            queue_name(str): The name of the new queue.