dep.js

define([], function () {
    /** @class DepClassName */
    var exports = {
        helloWorld: function() {
            console.log("Hello world");
        }
    };
    return exports;
});

primary.js

define(['./dep'], function (/** DepClassName */dep) {
    var exports = {
        sayHello: function() {
            dep.helloWorld(); // helloWorld() will be compeled here after 'dep.'
        }
    };
    return exports;
});