def main() {
    field mut x = 2**4;
    assert(x == 16);
    x = x**2;
    assert(x == 256);
    field y = 3**3;
    assert(y == 27);
    field z = y**2;
    assert(z == 729);
    field mut a = 5**2;
    assert(a == 25);
    a = a**2;
    assert(a == 625);
    a = 5**5;
    assert(a == 3125);
    return;
}