type Holder {
    value: ref<i32>,
}

fn replace(holder: mutref<Holder>, next: ref<i32>) -> Void {
    holder.value = next
}

pub fn main() -> Void {
    var old: i32 = 1
    let next: i32 = 2
    var other: i32 = 3
    var holder: Holder = Holder { value: &old }
    let selected: mutref<Holder> = &mut holder
    if true {
        var holder: Holder = Holder { value: &other }
        replace(selected, &next)
    }
    old = 4
}