code: func (logger *Logger) InitTag(tag ...string) {
  	var t string
  	var index uint64 // first index
  	if len(tag) > 0 {
  		t = tag[0]
  	} else {
  		id, err := uuid.NewV4()
  		if err != nil {
  			panic(fmt.Errorf("error generating uuid: " + err.Error()))
  		}
  		t = id.String()[0:8]
  	}
  	logger.tagMap.Store(index, t)
  }
docs: // InitTag sets the tag for the main thread.