code: func (q *queue) ExpireReceipts(timeout time.Duration) map[string]int {
  	q.lock.Lock()
  	defer q.lock.Unlock()
  
  	return q.expire(timeout, q.receiptPendPool, q.receiptTaskQueue, receiptTimeoutMeter)
  }
docs: // ExpireReceipts checks for in flight receipt requests that exceeded a timeout
  // allowance, canceling them and returning the responsible peers for penalisation.