let test =
    let x = ref 5;
    let y = ref 0;
    while (!x >? 0) {
      x := !x - 1;
      y := !y + 1
    };
    if (!y =? 5) then {
      print_string ("This test is OK!\n")
    } else {
      print_string ("This is KO!\n")
    }