code: func NewNetStore(store SyncChunkStore, nnf NewNetFetcherFunc) (*NetStore, error) {
  	fetchers, err := lru.New(defaultChunkRequestsCacheCapacity)
  	if err != nil {
  		return nil, err
  	}
  	return &NetStore{
  		store:             store,
  		fetchers:          fetchers,
  		NewNetFetcherFunc: nnf,
  		closeC:            make(chan struct{}),
  	}, nil
  }
docs: // NewNetStore creates a new NetStore object using the given local store. newFetchFunc is a
  // constructor function that can create a fetch function for a specific chunk address.