{UpperCase, 0x10450, 0x10450},
	{LowerCase, 0x10450, 0x10450},
	{TitleCase, 0x10450, 0x10450},

	// Non-letters with case.
	{LowerCase, 0x2161, 0x2171},
	{UpperCase, 0x0345, 0x0399},
}

func TestIsLetter(t *testing.T) {
	for _, r := range upperTest {
		if !IsLetter(r) {
			t.Errorf("IsLetter(U+%04X) = false, want true", r)
		}
	}
	for _, r := range letterTest {
		if !IsLetter(r) {