code: func (f *fetcher) deliver(ctx context.Context, ch Chunk) {
  	f.deliverOnce.Do(func() {
  		f.chunk = ch
  		// closing the deliveredC channel will terminate ongoing requests
  		close(f.deliveredC)
  		log.Trace("n.getFetcher close deliveredC", "ref", ch.Address())
  	})
  }
docs: // deliver is called by NetStore.Put to notify all pending requests