code: func (server *Server) ServeConnWithContext(conn io.ReadWriteCloser, context interface{}) {
  	buf := bufio.NewWriter(conn)
  	srv := &gobServerCodec{conn, gob.NewDecoder(conn), gob.NewEncoder(buf), buf}
  	server.ServeCodecWithContext(srv, context)
  }
docs: // ServeConnWithContext is like ServeConn but makes it possible to
  // pass a connection context to the RPC methods.