choice Event {
    key: i32,
    quit,
}

pub fn main(world: World) -> Void raises {
    let event: Event = Event.quit
    match event {
        .key(code) {
            if code == 1 {
                check world.out.write("unexpected key\n")
            }
        }
        _ {
            check world.out.write("choice fallback ok\n")
        }
    }
}