SubZZ := func(z, x, y *Int) *Int { return z.Sub(x, y) }
	for _, a := range sumZZ {
		arg := a
		testFunZZ(t, "AddZZ", AddZZ, arg)

		arg = argZZ{a.z, a.y, a.x}
		testFunZZ(t, "AddZZ symmetric", AddZZ, arg)

		arg = argZZ{a.x, a.z, a.y}
		testFunZZ(t, "SubZZ", SubZZ, arg)

		arg = argZZ{a.y, a.z, a.x}
		testFunZZ(t, "SubZZ symmetric", SubZZ, arg)
	}
}

func TestProdZZ(t *testing.T) {