System.Xml.Xsl.Runtime.XsltFunctions.Lang C# (CSharp) Method

        public static bool Lang(string value, XPathNavigator context)
        {
            string lang = context.XmlLang;

            if (!lang.StartsWith(value, StringComparison.OrdinalIgnoreCase))
            {
                return false;
            }
            return (lang.Length == value.Length || lang[value.Length] == '-');
        }