code: func reqRaftJoin(join, raftAddr string) error {
  	resp, _, err := raftredcon.Do(join, nil, []byte("raftaddpeer"), []byte(raftAddr))
  	if err != nil {
  		return err
  	}
  	if string(resp) != "OK" {
  		return errors.New("invalid response")
  	}
  	return nil
  }
docs: // reqRaftJoin does a remote "RAFTJOIN" command at the specified address.