Hello I would like to inherit JavaScript file gantt.js in web_gantt module.

My code is like that

openerp.mrp_smart_planning = function(instance){
    var module = instance.web_gantt;
    module.GanttView.include({
        init : function(){
            alert('Hello!');
            module._super();
        },
    });
};

(in file named mrp_smart_planning.js)

After reloading webpage, when I want to see gantt view "Hello" alert appear, but after shows windows with text below: Uncaught TypeError: Cannot read property '_model' of undefined