docs: func (a *API) Attach(filename string) {
  	a.path = filepath.Dir(filename)
  	f, err := os.Open(filename)
  	defer f.Close()
  	if err != nil {
  		panic(err)
  	}
  	if err := json.NewDecoder(f).Decode(a); err != nil {
  		panic(fmt.Errorf("failed to decode %s, err: %v", filename, err))
  	}
  }