Hello, I am trying to inheriting var Pos from point_of_sale from openerp 6.1 module to override get_app_data() function please help me. Here is my code for referance which gives error "module is undefined": This is my inherited js file:

openerp.my_pos = function(instance){

instance.my_pos = {};

var module = instance.point_of_sale;

var _super_ = module.Pos.prototype.get_app_data;

module.Pos.prototype.get_app_data = function(){
     console.log('Hello!');
     _super_.call(this);
};

};