visionmedia/express — pull request #1936 by defunctzombie (2014-02-27 00:58:56+00:00)
Title: make express.Router() return a Router function instance

Similar to how express() returns an express `app` instance which is also
a function, express.Router() returns the Router instance which is also a
function and can be easily used via another router or the app.

app.use(express.Router());