code: public static boolean isDelayedQueue(final Jedis jedis, final String key) {
          return ZSET.equalsIgnoreCase(jedis.type(key));
      }
docs: Determines if the queue identified by the given key is a delayed queue.
  
  @param jedis
  connection to Redis
  @param key
  the key that identifies a queue
  @return true if the key identifies a delayed queue, false otherwise