code: func SetConfigValue(section, key, val string) error {
  	Cfg.SetValue(section, key, val)
  	if err := goconfig.SaveConfigFile(Cfg, ConfigFile); err != nil {
  		return fmt.Errorf("fail to set config value(%s:%s=%s): %v", section, key, val, err)
  	}
  	return nil
  }
docs: // SetConfigValue sets and saves gopm configuration.