code: func GetHub(storage interface{}) BlobHub {
  	if h, ok := getHub(storage); ok {
  		return h
  	}
  	hubmu.Lock()
  	defer hubmu.Unlock()
  	h, ok := stohub[storage]
  	if ok {
  		return h
  	}
  	h = new(memHub)
  	stohub[storage] = h
  	return h
  }
docs: // GetHub return a BlobHub for the given storage implementation.