```js
const albums = require('express').Router();
const tracks = require('./tracks').Router();

//...

// Our root route to /albums
albums.get('/', function(req, res, next) {
  // res.send() our response here
});

// A route to handle requests to any individual album, identified by an album id
albums.get('/:albumId', function(req, res, next) {
  let albumId = req.params.albumId;
  // retrieve album from database using albumId
  // res.send() response with album data
});

// Note, this route represents /albums/:albumId/tracks because our top-level router is already forwarding /albums to our Albums router!
albums.use('/:albumId/tracks', tracks);

//...

module.exports = albums;
```