code: func (c *EtcdGroupService) GroupRemoveMember(ctx context.Context, groupName, uid string) error {
  	ctxT, cancel := context.WithTimeout(ctx, transactionTimeout)
  	defer cancel()
  	etcdRes, err := clientInstance.Txn(ctxT).
  		If(clientv3.Compare(clientv3.CreateRevision(memberKey(groupName, uid)), ">", 0)).
  		Then(clientv3.OpDelete(memberKey(groupName, uid))).
  		Commit()
  
  	if err != nil {
  		return err
  	}
  	if !etcdRes.Succeeded {
  		return constants.ErrMemberNotFound
  	}
  	return nil
  }
docs: // GroupRemoveMember removes specified UID from group