type metacacheBlockWriter struct {
	wg           sync.WaitGroup
	streamErr    error
	blockEntries int
}

// newMetacacheBlockWriter provides a streaming block writer.
// Each block is the size of the capacity of the input channel.
// The caller should close to indicate the stream has ended.
func newMetacacheBlockWriter(in <-chan metaCacheEntry, nextBlock func(b *metacacheBlock) error) *metacacheBlockWriter {

				}
			}
			metaMu.Unlock()
		}
	}()

	const retryDelay = 200 * time.Millisecond
	const maxTries = 5

	// Keep destination...
	// Write results to disk.
	bw := newMetacacheBlockWriter(entries, func(b *metacacheBlock) error {
		// if the block is 0 bytes and its a first block skip it.
		// skip only this for Transient caches.
		if len(b.data) == 0 && b.n == 0 && o.Transient {
			return nil
		}