code: func (m *ownerManager) GetOwnerID(ctx context.Context) (string, error) {
  	resp, err := m.etcdCli.Get(ctx, m.key, clientv3.WithFirstCreate()...)
  	if err != nil {
  		return "", errors.Trace(err)
  	}
  	if len(resp.Kvs) == 0 {
  		return "", concurrency.ErrElectionNoLeader
  	}
  	return string(resp.Kvs[0].Value), nil
  }
docs: // GetOwnerID implements Manager.GetOwnerID interface.