var sum = 0;

for (x : [1,2,3,4]) {
  sum += x;
}

assert_equal(sum, 10)

var result = 0.0;

for (x : retro(range([1,2,3,4]))) {
  if (result == 0.0) {
    result = x;
  } else {
    result /= x;
  }
}

assert_true(result > .6 && result < .7);