// this code does not need to be flattened
def main(field x, field y, field z) -> field {
    field a = x + 3 * y - z * 2 - x * 12;
    assert(3*y - z * 2 - x * 12 == a - x);
    assert((x + y) - ((z + 3*x) - y) == (x - y) + ((2*x - 4*y) + (4*y - 2*z)));
    return x;
}