Mounting sub apps with express

_app.js

var express = require('express'),
    app = express();

var api = require('./api.js'),
    embeds = require('./sub-app-2.js');

app.use(api);
app.use(embeds);

app.listen(3000);

api.js

var express = require('express'),
    app = express();
    
app.get('/api', function(req, res) {
  res.send('hello from api');
});

module.exports = app;

embeds.js

var express = require('express'),
    app = express();
    
app.get('/embeds', function(req, res) {
  res.send('hello from embeds');
});

module.exports = app;