C# xml格式化输出函数

   private string FormatXml(string sUnformattedXml)        {            XmlDocument xd = new XmlDocument();            xd.LoadXml(sUnformattedXml);            StringBuilder sb = new StringBuilder();            StringWriter sw = new StringWriter(sb);            XmlTextWriter xtw = null;            try            {                xtw = new XmlTextWriter(sw);                xtw.Formatting = Formatting.Indented;                xtw.Indentation = 1;                xtw.IndentChar = '\t';                xd.WriteTo(xtw);            }            finally            {                if (xtw != null)                    xtw.Close();            }            return sb.ToString();        }