code: func (q *RateLimitedTimedQueue) Add(value string, uid interface{}) bool {
  	now := now()
  	return q.queue.Add(TimedValue{
  		Value:     value,
  		UID:       uid,
  		AddedAt:   now,
  		ProcessAt: now,
  	})
  }
docs: // Add value to the queue to be processed. Won't add the same
  // value(comparison by value) a second time if it was already added
  // and not removed.