router 使用的时候没有此方法，求知道

app.use(express.router(routes));
                ^
TypeError: Object function createApplication() {
  var app = connect();
  utils.merge(app, proto);
  app.request = { __proto__: req, app: app };
  app.response = { __proto__: res, app: app };
  app.init();
  return app;
} has no method 'router'