fn guarded(value: i32) -> i32 raises [Negative] {
    if value < 0 {
        raise Negative
    }
    return value
}

pub fn main(world: World) -> Void raises {
    let value: i32 = check guarded(7)
    if value == 7 {
        check world.out.write("exceptions ok\n")
    }
}