You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: strings.go
    path of file: ./repos/corteza/extra/server-discovery/vendor/google.golang.org/protobuf/internal/strs
    
    the code of the file until where you have to start completion: // Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package strs provides string manipulation functionality specific to protobuf.
package strs

import (
	"go/token"
	"strings"
	"unicode"
	"unicode/utf8"

	"google.golang.org/protobuf/internal/flags"
	"google.golang.org/protobuf/reflect/protoreflect"
    
func GoSanitized(s string) string {
	// Sanitize the input to the set of valid characters,
	// which must be '_' or be in the Unicode L or N categories.
	s = strings.Map(func(r rune) rune {
		if unicode.IsLetter(r) || unicode.IsDigit(r) {
			return r
		}
		return '_'
	}, s)

	// Prepend '_' in the event of a Go keyword conflict or if
	// the identifier is invalid (does not start in the Unicode L category).
	r, _ := utf8.DecodeRuneInString(s)
	if token.Lookup(s).IsKeyword() || !unicode.IsLetter(r) {
		return "_" + s
	}
	return s
}