func ContainsFunc(b []byte, f func(rune) bool) bool {
	return IndexFunc(b, f) >= 0
}

// IndexByte returns the index of the first instance of c in b, or -1 if c is not present in b.
func IndexByte(b []byte, c byte) int {
	return bytealg.IndexByte(b, c)
}

func indexBytePortable(s []byte, c byte) int {
	for i, b := range s {
		if b == c {
			return i
		}
	}
	return -1

func ParseUnverifiedStandardClaims(token []byte, claims *StandardClaims, buf []byte) (*SigningMethodHMAC, error) {
	if bytes.Count(token, []byte(".")) != 2 {
		return nil, jwtgo.ErrSignatureInvalid
	}

	i := bytes.IndexByte(token, '.')
	j := bytes.LastIndexByte(token, '.')

	n, err := base64DecodeBytes(token[:i], buf)
	if err != nil {
		return nil, &jwtgo.ValidationError{Inner: err, Errors: jwtgo.ValidationErrorMalformed}
	}

	fmt.Println(bytes.Index([]byte("chicken"), []byte("dmr")))
	// Output:
	// 4
	// -1
}

func ExampleIndexByte() {
	fmt.Println(bytes.IndexByte([]byte("chicken"), byte('k')))
	fmt.Println(bytes.IndexByte([]byte("chicken"), byte('g')))
	// Output:
	// 4
	// -1
}

func ExampleIndexFunc() {
	f := func(c rune) bool {
		return unicode.Is(unicode.Han, c)
	}

		forward := ""
		if len(opts.ForwardTo) > 0 && strings.HasPrefix(opts.ForwardTo, current) {
			forward = strings.TrimPrefix(opts.ForwardTo, current)
			// Trim further directories and trailing slash.
			if idx := strings.IndexByte(forward, '/'); idx > 0 {
				forward = forward[:idx]
			}
		}
		if contextCanceled(ctx) {
			return ctx.Err()
		}
		if opts.Limit > 0 && objsReturned >= opts.Limit {
			return nil
		}

	case []any:
		return transformInterfaceArray(v)
	case map[any]any:
		return transformInterfaceMap(v)
	default:
		return v
	}
}

func servicePortPrefixed(n string) bool {
	i := strings.IndexByte(n, '-')
	if i >= 0 {
		n = n[:i]
	}
	p := protocol.Parse(n)
	return p == protocol.Unsupported
}

func handleNamespace(istioNamespace string) string {
	if istioNamespace == "" {

			// if the revision is "default", render templates with an empty revision
			if rev == util.DefaultRevisionName {
				rev = ""
			}
			injectorAddress := centralOpts.Xds
			index := strings.IndexByte(injectorAddress, ':')
			if index != -1 {
				injectorAddress = injectorAddress[:index]
			}
			injector, meshConfig, err := setupKubeInjectParameters(cliContext, &sidecarTemplate, &valuesConfig, rev, injectorAddress)

// newline.
func ScanLines(data []byte, atEOF bool) (advance int, token []byte, err error) {
	if atEOF && len(data) == 0 {
		return 0, nil, nil
	}
	if i := bytes.IndexByte(data, '\n'); i >= 0 {
		// We have a full newline-terminated line.
		return i + 1, dropCR(data[0:i]), nil
	}
	// If we're at EOF, we have a final, non-terminated line. Return it.
	if atEOF {

	input := bufio.NewScanner(bytes.NewReader(valueBuffer.Bytes()))
	for input.Scan() {
		line := strings.TrimSpace(input.Text())
		if line == "" {
			continue
		}
		// Find first separator.
		idx := strings.IndexByte(line, trailerKVSeparator[0])
		if idx <= 0 || idx >= len(line) {
			if cr.debug {
				fmt.Printf("index, ':' not found in %q\n", line)
			}
			return errMalformedEncoding
		}
		key := line[:idx]

// ReadSlice returns err != nil if and only if line does not end in delim.
func (b *Reader) ReadSlice(delim byte) (line []byte, err error) {
	s := 0 // search start index
	for {
		// Search buffer.
		if i := bytes.IndexByte(b.buf[b.r+s:b.w], delim); i >= 0 {
			i += s
			line = b.buf[b.r : b.r+i+1]
			b.r += i + 1
			break
		}

		// Pending error?
		if b.err != nil {
			line = b.buf[b.r:b.w]
			b.r = b.w

	line = append(line, slice...)
	return line, err
}

// readSlice is like ReadBytes but returns a reference to internal buffer data.
func (b *Buffer) readSlice(delim byte) (line []byte, err error) {
	i := IndexByte(b.buf[b.off:], delim)
	end := b.off + i + 1
	if i < 0 {
		end = len(b.buf)
		err = io.EOF
	}
	line = b.buf[b.off:end]
	b.off = end
	b.lastRead = opRead
	return line, err
}