code: func ExpandConfigPath(path, defaultPath string) (string, error) {
  	if path != "" {
  		return ExpandPath(path, false)
  	}
  
  	configHome := lookupConfigHome()
  	if configHome != "" {
  		return filepath.Join(configHome, defaultPath), nil
  	}
  
  	return ExpandPath(fmt.Sprintf("~/.config/%s", defaultPath), false)
  }
docs: // ExpandConfigPath returns a copy of path expanded as with ExpandPath.  If the
  // path is empty, the default path is looked up inside $XDG_CONFIG_HOME, or
  // ~/.config if that is not set.