C# Normalize Newline

Newline.cs

using System.Text.RegularExpressions;

public static class StringHelpers {
    private const char _cr = '\u000D';
    private const char _lf = '\u000A';

    private const string _crlf = _cr + _lf;
    private static Regex _crlfRegex = new Regex(_cr + '|' + _lf + '|' +  _crlf);

    public static string NormalizeNewline(this string str){
        return _crlfRegex.Replace(str, "\n");
    }
}