return trimLeftASCII(trimRightASCII(s, &as), &as)
	}
	return trimLeftUnicode(trimRightUnicode(s, cutset), cutset)
}

// TrimLeft returns a subslice of s by slicing off all leading
// UTF-8-encoded code points contained in cutset.
func TrimLeft(s []byte, cutset string) []byte {
	if len(s) == 0 {
		// This is what we've historically done.
		return nil
	}
	if cutset == "" {
		return s
	}

}

func isHexes(s string) bool {
	if s == "" {
		return false
	}
	if s == "empty" {
		return true
	}
	for _, f := range strings.Split(s, " or ") {
		if f == "" || len(f)%2 != 0 || strings.TrimLeft(f, "0123456789abcdef") != "" {
			return false
		}
	}
	return true
}

// It would be nice if the error messages always began with
// the standard file:line: prefix,

	{"Trim", []byte{'a', 'b'}, "ab", nil},
	{"Trim", []byte("☺"), "☺", nil},
	{"TrimLeft", nil, "", nil},
	{"TrimLeft", []byte{}, "", nil},
	{"TrimLeft", []byte{'a'}, "a", nil},
	{"TrimLeft", []byte{'a', 'a'}, "a", nil},
	{"TrimLeft", []byte{'a'}, "ab", nil},
	{"TrimLeft", []byte{'a', 'b'}, "ab", nil},
	{"TrimLeft", []byte("☺"), "☺", nil},
	{"TrimRight", nil, "", nil},
	{"TrimRight", []byte{}, "", []byte{}},

	// Output:
	// -gopher!
	// "go-gopher!"
	// go-gopher
	// go-gopher!
}

func ExampleTrimLeft() {
	fmt.Print(string(bytes.TrimLeft([]byte("453gopher8257"), "0123456789")))
	// Output:
	// gopher8257
}

func ExampleTrimLeftFunc() {
	fmt.Println(string(bytes.TrimLeftFunc([]byte("go-gopher"), unicode.IsLetter)))

pkg bytes, func ToUpperSpecial(unicode.SpecialCase, []uint8) []uint8
pkg bytes, func Trim([]uint8, string) []uint8
pkg bytes, func TrimFunc([]uint8, func(int32) bool) []uint8
pkg bytes, func TrimLeft([]uint8, string) []uint8
pkg bytes, func TrimLeftFunc([]uint8, func(int32) bool) []uint8
pkg bytes, func TrimRight([]uint8, string) []uint8
pkg bytes, func TrimRightFunc([]uint8, func(int32) bool) []uint8