static void trimWhitespace(XmlDocumentFragment fragment)
        {
            while (fragment.FirstChild != null && fragment.FirstChild.NodeType == XmlNodeType.Whitespace)
                fragment.RemoveChild(fragment.FirstChild);

            while (fragment.LastChild != null && fragment.LastChild.NodeType == XmlNodeType.Whitespace)
                fragment.RemoveChild(fragment.LastChild);
        }