// out 参数测试 — 引用传递
fn swap(out x: i64, out y: i64) -> void {
    let t = x;
    x = y;
    y = t;
}

fn increment(out x: i64) -> void {
    x = x + 1;
}

fn main() -> void {
    let a = 10;
    let b = 20;
    print_i64(a);
    print_i64(b);
    swap(a, b);
    print_i64(a);
    print_i64(b);
    increment(a);
    print_i64(a);
}