How to set default path (route prefix) in express?

Instead of doing path + '..' foreach route - how can I prefix every route?

My route shall be

/api/v1/user

What I don't want to do

var path = '/api/v1';
app.use(path + '/user', user);

What I want to do

 var app = express();
 app.setPath('/api/v1');
 app.use(..);

Using Express 4 you can use Router

var router = express.Router();
router.use('/user', user);

app.use('/api/v1', router);