private static string MakeLinksAbsolute(HtmlParser parser, HtmlMarkupFormatter formatter, IExecutionContext context, string value)
 {
     if (!string.IsNullOrEmpty(value))
     {
         IHtmlDocument          dom      = parser.Parse(string.Empty);
         INodeList              nodes    = parser.ParseFragment(value, dom.Body);
         IEnumerable <IElement> elements = nodes.SelectMany(x => x.Descendents <IElement>().Where(y => y.HasAttribute("href") || y.HasAttribute("src")));
         bool replaced = false;
         foreach (IElement element in elements)
         {
             replaced = MakeLinkAbsolute(element, "href", context) || replaced;
             replaced = MakeLinkAbsolute(element, "src", context) || replaced;
         }
         if (replaced)
         {
             using (StringWriter writer = new StringWriter())
             {
                 nodes.ToHtml(writer, formatter);
                 return(writer.ToString());
             }
         }
     }
     return(null);
 }