var f;

fun f1() {
  var a = "a";
  fun f2() {
    var b = "b";
    fun f3() {
      var c = "c";
      fun f4() {
        print a;
        print b;
        print c;
      }
      f = f4;
    }
    f3();
  }
  f2();
}
f1();

f();
// out: a
// out: b
// out: c