docs: def p_queue(p):
      """
      queue : QUEUE COLON LIFO
            | QUEUE COLON FIFO
      """
      if p[3] == "LIFO":
          p[0] = {"queue": LIFO()}
  
      elif p[3] == "FIFO":
          p[0] = {"queue": FIFO()}
  
      else:
          raise RuntimeError("Queue discipline '%s' is not supported!" % p[1])