code: func New(config types.Config, embededStorage bool) (*Mercury, error) {
  	var cliv3 *clientv3.Client
  	var err error
  	if embededStorage {
  		cliv3 = embeded.NewCluster()
  		log.Info("[Mercury] use embeded cluster")
  	} else if cliv3, err = clientv3.New(clientv3.Config{Endpoints: config.Etcd.Machines}); err != nil {
  		return nil, err
  	}
  	return &Mercury{cliv3: cliv3, config: config}, nil
  }
docs: // New for create a Mercury instance