code: func (q *UniqueQueue) Add(value TimedValue) bool {
  	q.lock.Lock()
  	defer q.lock.Unlock()
  
  	if q.set.Has(value.Value) {
  		return false
  	}
  	heap.Push(&q.queue, &value)
  	q.set.Insert(value.Value)
  	return true
  }
docs: // Add a new value to the queue if it wasn't added before, or was
  // explicitly removed by the Remove call. Returns true if new value
  // was added.