code: func backupName(name string, local bool) string {
  	dir := filepath.Dir(name)
  	filename := filepath.Base(name)
  	ext := filepath.Ext(filename)
  	prefix := filename[:len(filename)-len(ext)]
  	t := currentTime()
  	if !local {
  		t = t.UTC()
  	}
  
  	timestamp := t.Format(backupTimeFormat)
  	return filepath.Join(dir, fmt.Sprintf("%s-%s%s", prefix, timestamp, ext))
  }
docs: // backupName creates a new filename from the given name, inserting a timestamp
  // between the filename and the extension, using the local time if requested
  // (otherwise UTC).