code: func (s *Server) addResponseNodes(d krpc.Msg) {
  	if d.R == nil {
  		return
  	}
  	d.R.ForAllNodes(func(ni krpc.NodeInfo) {
  		s.getNode(NewAddr(ni.Addr.UDP()), int160FromByteArray(ni.ID), true)
  	})
  }
docs: // Add response nodes to node table.