fn numberAfterA(text: Span<u8>) -> u32 {
    var value: u32 = 0
    var i: usize = 1
    while i < std.mem.len(text) {
        value = value * 10 + (text[i] - 48) as u32
        i = i + 1
    }
    return value
}

pub fn main(world: World) -> Void raises {
    if numberAfterA(std.mem.span("a2")) < numberAfterA(std.mem.span("a10")) {
        check world.out.write("natural sort ok\n")
    }
}