NodeJS Modularization with Callback

callback.js

//module example.js
var exports = {};
exports.search = function(firstName, lastName, callback) {
    this.thedude = {};
    this.thedude.name = firstName + ' ' + lastName;
    callback(this.thedude.name);
};
module.exports = exports;
//end of example.js


//module whatever.js
var module_example = require('./example.js');

module_example.search('Big', 'Lebowski', function(err, data){
  console.log(err, data); // « 'Big Lebowski'
});
//end of whatever.js