JavaScript: How do use instance variables
===

why doesn't this work as expected. (see expected comment)

    var Module = function () {
        var public_instance_var;
        
        function doStuff () {
            Module.doOtherStuff();
            console.log(public_instance_var); // expected: true, but logs undefined
        };
        
        function doOtherStuff() {
            public_instance_var = true;
        };

        return {
            public_instance_var: instance_var
        }
    }();

    Module.doStuff();


