code: func (w *wsRPCDialer) DialRPC(id enode.ID) (*rpc.Client, error) {
  	addr, ok := w.addrs[id.String()]
  	if !ok {
  		return nil, fmt.Errorf("unknown node: %s", id)
  	}
  	return rpc.DialWebsocket(context.Background(), addr, "http://localhost")
  }
docs: // DialRPC implements the RPCDialer interface by creating a WebSocket RPC
  // client of the given node