// upper case using the case mapping specified by c.
func ToUpperSpecial(c unicode.SpecialCase, s string) string {
	return Map(c.ToUpper, s)
}

// ToLowerSpecial returns a copy of the string s with all Unicode letters mapped to their
// lower case using the case mapping specified by c.
func ToLowerSpecial(c unicode.SpecialCase, s string) string {
	return Map(c.ToLower, s)
}