  num a = 100;
  b  = 200;
  @c = 300;
  $d = 400;
  for (num i = 1; i < 1024; i *= 2) {
    a  += 1;
    b  += 1;
    @c += 1;
    $d += 1;
    $oa = a;
    $ob = b;
    $oc = @c;
    $od = $d;
  }

