fn nextPrime(after: u32) -> u32 {
    var n: u32 = after + 1
    while true {
        if std.math.isPrimeU32(n) {
            return n
        }
        n = n + 1
    }
    return 0
}

pub fn main(world: World) -> Void raises {
    if nextPrime(30) == 31 {
        check world.out.write("prime generator ok\n")
    }
}