code: func (n *Node) doRaftAddPeer(conn redcon.Conn, cmd redcon.Command) (interface{}, error) {
  	if len(cmd.Args) != 2 {
  		return nil, ErrWrongNumberOfArguments
  	}
  	n.log.Noticef("Received add peer request from %v", string(cmd.Args[1]))
  	f := n.raft.AddPeer(string(cmd.Args[1]))
  	if f.Error() != nil {
  		return nil, f.Error()
  	}
  	n.log.Noticef("Node %v added successfully", string(cmd.Args[1]))
  	conn.WriteString("OK")
  	return nil, nil
  }
docs: // doRaftAddPeer handles a "RAFTADDPEER address" client command.