code: func (s *Server) SendTo(to *Node, m Message) error {
  	msg, err := s.serializer.Marshal(m)
  	if err != nil {
  		return fmt.Errorf("marshaling message: %v", err)
  	}
  	msg = append([]byte{getMessageType(m)}, msg...)
  	return s.defaultClient.SendMessage(context.Background(), &to.URI, msg)
  }
docs: // SendTo represents an implementation of Broadcaster.