fn shrink(bytes: Span<u8>, n: usize) -> Bool {
    if n == 0 {
        return true
    }
    if n == 1 {
        let tail: Bool = shrink(bytes, n - 1)
        return tail
    }
    let skip: Bool = shrink(bytes, n - 2)
    return skip
}

pub fn main(world: World) -> Void raises {
    let bytes: Span<u8> = std.mem.span("zero")
    if shrink(bytes, 5) && shrink(bytes, 4) {
        check world.out.write("recursive multi call ok\n")
    }
}