}
		// equal is symmetric
		x, y = y, x
		if got := x.equal(y); got != want {
			t.Errorf("%v.equal(%v) = %v; want %v", x, y, got, want)
		}
	}
}

func TestTermUnion(t *testing.T) {
	for _, test := range []string{
		"∅ ∅ ∅ ∅",
		"∅ 𝓤 𝓤 ∅",
		"∅ int int ∅",
		"∅ ~int ~int ∅",
		"∅ myInt myInt ∅",
		"𝓤 𝓤 𝓤 ∅",
		"𝓤 int 𝓤 ∅",
		"𝓤 ~int 𝓤 ∅",
		"𝓤 myInt 𝓤 ∅",

		}
		// equal is symmetric
		x, y = y, x
		if got := x.equal(y); got != want {
			t.Errorf("%v.equal(%v) = %v; want %v", x, y, got, want)
		}
	}
}

func TestTermUnion(t *testing.T) {
	for _, test := range []string{
		"∅ ∅ ∅ ∅",
		"∅ 𝓤 𝓤 ∅",
		"∅ int int ∅",
		"∅ ~int ~int ∅",
		"∅ myInt myInt ∅",
		"𝓤 𝓤 𝓤 ∅",
		"𝓤 int 𝓤 ∅",
		"𝓤 ~int 𝓤 ∅",
		"𝓤 myInt 𝓤 ∅",