Getting webpage not available errors when trying to run Routes example code with Node

Javascript newbie here..

I've trying to run the example code given in the routes documentation.

Code:

var Router = require('routes');
var router = new Router();

router.addRoute('/admin/*?', auth);
router.addRoute('/admin/users', adminUsers);

http.createServer(function (req, res) {
  var path = url.parse(req.url).pathname;
  var match = router.match(path);
  match.fn(req, res, match);
}).listen(1337)

// authenticate the user and pass them on to
// the next route, or respond with 403.
function auth(req, res, match) {
  if (checkUser(req)) {
    match = match.next();
    if (match) match.fn(req, res, match);
    return;
  }
  res.statusCode = 403;
  res.end()
}

// render the admin.users page
function adminUsers(req, res, match) {
  // send user list
  res.statusCode = 200;
  res.end();
}

I can run this via node app.js and it starts up fine. However, when I hit http://localhost:1337/admin I get the following error:

TypeError: Cannot call method 'fn' of undefined  

To make sure I wasn't doing something wrong in the server, I reset it back to the example Node app:

http.createServer(function (req, res) {
  .write("Hello world!");
  res.end();
}).listen(1337)

And this runs fine. I can hit localhost and see it print out hello world. So why am I getting a type error when I run the routes example code?