notes: """
  CoffeeScript has a `for x of y` construct that compiles into JavaScript as
  `for (var x in y)`. However, there is no direct equivalent for `for (x in y)`
  without the `var` prefix.

  While using such construct is undesirable, some popular libraries use
  `for..in` without `var`, taking advantage of its side effect: using a variable in
  the higher scope.

  > ```js
  > function fn () {
  >   var x, object = { a: 2, b: 3 };
  >   console.log(x); //=> undefined
  >
  >   for (x in object) { /* ... */ }
  >   console.log(x); //=> 'b'
  > ```

  Js2coffee works around this.
"""
----
for (x in y) {
  alert(x);
}
----
for x_ of y
  `x = x_`
  alert x_
