code: func (q *UniqueQueue) Get() (TimedValue, bool) {
  	q.lock.Lock()
  	defer q.lock.Unlock()
  	if len(q.queue) == 0 {
  		return TimedValue{}, false
  	}
  	result := heap.Pop(&q.queue).(*TimedValue)
  	q.set.Delete(result.Value)
  	return *result, true
  }
docs: // Get returns the oldest added value that wasn't returned yet.