code: func NewHolder() *Holder {
  	return &Holder{
  		indexes: make(map[string]*Index),
  		closing: make(chan struct{}),
  
  		opened: lockedChan{ch: make(chan struct{})},
  
  		translateFile:            NewTranslateFile(),
  		NewPrimaryTranslateStore: newNopTranslateStore,
  
  		broadcaster: NopBroadcaster,
  		Stats:       stats.NopStatsClient,
  
  		NewAttrStore: newNopAttrStore,
  
  		cacheFlushInterval: defaultCacheFlushInterval,
  
  		Logger: logger.NopLogger,
  	}
  }
docs: // NewHolder returns a new instance of Holder.