fn opt_0_10_20(x int) ?int {
    if x < 0 || (x >= 10 && x <= 20) {
        return none
    }
    return x
}

fn test_options_in_for_loop_break() {
    mut sum := 0
    mut nbreaks := 0
    for i := 5; i < 15; i++ {
        x := opt_0_10_20(i) or {
            nbreaks++
            break
        }
        sum += x
        // println('i: ${i:3} | sum: ${sum:3}')
    }
    assert nbreaks == 1
    assert sum == 35
}

fn test_options_in_for_loop_continue() {
    mut sum := 0
    mut ncontinue := 0
    for i := -5; i < 30; i++ {
        x := opt_0_10_20(i) or {
            ncontinue++
            continue
        }
        sum += x
        // println('i: ${i:3} | sum: ${sum:3}')
    }
    assert ncontinue == 16
    assert sum == 270
}