How to use helpers in Express 3.x

gistfile1.txt

//helpers.js

var moment = require('moment');

var helpers = {

    nice_date: function(raw_date) {
        return moment(raw_date).format('LL');
    }

};

module.exports.load = function(app) {
    _.extend(app.locals, helpers);
};


//app.js (MAIN)
var helpers = require('./helpers.js');
var urls = require('./urls.js');

var start_server = function() {
    app.set('views', __dirname + '/views');
    app.set('view engine', 'jade');
    app.use(express.static(__dirname + '/public'));
    app.use(express.logger());
    
    helpers.load(app); // <----------
    
    urls.load(app); 

    app.listen(3000);
};

//and the in any view

p(style='font-family: Droid;') Price: <strong> € #{comic.price} </strong> - <em> #{nice_date(comic.date)} </em>