// only using sub, no need to flatten
def main(field x) -> field {
    field a = 5;
    field b = 7;
    field c = a == b ? 4 : 3;
    assert(c == 3);
    field d = a == 5 ? 1 : 2;
    assert(d == 1);
    field e = a < b ? 5 : 6;
    assert(e == 5);
    field f = b < a ? 7 : 8;
    assert(f == 8);
    return x;
}