function foo(){

            var a = 2;

            function bar(){

                console.log(a);

            }

            return bar;

        }

        var baz = foo();

        baz();

function once(fn) {

                let called = false

                return function() {

                    if (!called) {

                        called = true

                        fn.apply(this, arguments)

                    }

                }

            }