code: func NewEtcdGroupService(conf *config.Config, clientOrNil *clientv3.Client) (*EtcdGroupService, error) {
  	err := initClientInstance(conf, clientOrNil)
  	if err != nil {
  		return nil, err
  	}
  	return &EtcdGroupService{}, err
  }
docs: // NewEtcdGroupService returns a new group instance