code: func (q *queue) ShouldThrottleReceipts() bool {
  	q.lock.Lock()
  	defer q.lock.Unlock()
  
  	return q.resultSlots(q.receiptPendPool, q.receiptDonePool) <= 0
  }
docs: // ShouldThrottleReceipts checks if the download should be throttled (active receipt
  // fetches exceed block cache).