code: func New(maxBytes int64, cache, origin blobserver.Storage) *Storage {
  	sto := &Storage{
  		origin:        origin,
  		cache:         cache,
  		lru:           lru.NewUnlocked(0),
  		maxCacheBytes: maxBytes,
  	}
  	return sto
  }
docs: // New returns a proxycache blob storage that reads from cache,
  // then origin, populating cache as needed, up to a total of maxBytes.