fn err_call(ok bool) ?int {
    if ok {
        return 42
    }
    return none
}

fn test_if_opt() {
    if val := err_call(true) {
        eprintln('  val should be available here: ${val}')
        assert val == 42
    }
    assert true
}

fn test_simple_else_if_guard() {
    if false {
        assert false
    } else if val := err_call(true) {
        assert val == 42
    } else {
        assert false
    }
}

fn test_multiple_else_if_guard() {
    if _ := err_call(false) {
        assert false
    } else if val := err_call(false) {
        assert val == 0 // assert false
    } else if val := err_call(true) {
        assert val == 42
    } else {
        assert false
    }
}

fn test_opt_with_fall_through() {
    mut x := 1
    err_call(false) or {
        eprintln('  this *should* be an error: ${err}')
        x++
        assert true
    }
    assert x == 2
}