c := s[i]
			if 'a' <= c && c <= 'z' {
				c -= 'a' - 'A'
			}
			b[i] = c
		}
		return b
	}
	return Map(unicode.ToUpper, s)
}

// ToLower returns a copy of the byte slice s with all Unicode letters mapped to
// their lower case.
func ToLower(s []byte) []byte {
	isASCII, hasUpper := true, false
	for i := 0; i < len(s); i++ {
		c := s[i]
		if c >= utf8.RuneSelf {
			isASCII = false
			break
		}

func ExampleToLower() {
	fmt.Printf("%s", bytes.ToLower([]byte("Gopher")))
	// Output: gopher
}

func ExampleToLowerSpecial() {
	str := []byte("AHOJ VÝVOJÁRİ GOLANG")
	totitle := bytes.ToLowerSpecial(unicode.AzeriCase, str)
	fmt.Println("Original : " + string(str))
	fmt.Println("ToLower : " + string(totitle))
	// Output:
	// Original : AHOJ VÝVOJÁRİ GOLANG
	// ToLower : ahoj vývojári golang
}

		t.Errorf("invalidRune: expected %q got %q", expect, m)
	}
}

func TestToUpper(t *testing.T) { runStringTests(t, ToUpper, "ToUpper", upperTests) }

func TestToLower(t *testing.T) { runStringTests(t, ToLower, "ToLower", lowerTests) }

func BenchmarkToUpper(b *testing.B) {
	for _, tc := range upperTests {
		tin := []byte(tc.in)
		b.Run(tc.in, func(b *testing.B) {
			for i := 0; i < b.N; i++ {

pkg unicode, func IsUpper(int32) bool
pkg unicode, func SimpleFold(int32) int32
pkg unicode, func To(int, int32) int32
pkg unicode, func ToLower(int32) int32
pkg unicode, func ToTitle(int32) int32
pkg unicode, func ToUpper(int32) int32
pkg unicode, method (SpecialCase) ToLower(int32) int32
pkg unicode, method (SpecialCase) ToTitle(int32) int32
pkg unicode, method (SpecialCase) ToUpper(int32) int32