anchor.diff:      tree(Rest, append_stack_child(norm({Tag, Attrs}), S));
   tree([{start_tag, Tag, Attrs, false} | Rest], S) ->
       tree(Rest, stack(norm({Tag, Attrs}), S));
  +tree([T={comment, _Comment} | Rest], S) ->
  +    tree(Rest, append_stack_child(T, S));
   tree(L=[{data, _Data, _Whitespace} | _], S) ->
       case tree_data(L, true, []) of
           {_, true, Rest} -> 
  
positive.code: test() ->
      test_destack(),
      test_tokens(),
      test_parse_tokens(),
      test_escape(),
      test_escape_attr(),
  
negative.code:     {{start_tag, Tag, Attrs, Singleton}, Rest3, S3};
  tokenize(Rest, S) ->
      tokenize_data(Rest, S, [], true).
  
  test_parse() ->
      D0 = "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01//EN\" \"http://www.w3.org/TR/html4/strict.dtd\">
  <html>
   <head>
     <meta http-equiv=\"Content-Type\" content=\"text/html; charset=UTF-8\">
     <title>Foo</title>
     <link rel=\"stylesheet\" type=\"text/css\" href=\"/static/rel/dojo/resources/dojo.css\" media=\"screen\">
     <link rel=\"stylesheet\" type=\"text/css\" href=\"/static/foo.css\" media=\"screen\">
     <!--[if lt IE 7]>
     <style type=\"text/css\">
       .no_ie { display: none; }
     </style>
     <![endif]-->
     <link rel=\"icon\" href=\"/static/images/favicon.ico\" type=\"image/x-icon\">
     <link rel=\"shortcut icon\" href=\"/static/images/favicon.ico\" type=\"image/x-icon\">
   </head>
   <body id=\"home\" class=\"tundra\">
   </body>
  </html>",
      Expect = {"html", [],
                [{"head", [],
                  [{"meta",
                    [{"http-equiv","Content-Type"},
                     {"content","text/html; charset=UTF-8"}],
                    []},
                   {"title",[],["Foo"]},
                   {"link",
                    [{"rel","stylesheet"},
                     {"type","text/css"},
                     {"href","/static/rel/dojo/resources/dojo.css"},
                     {"media","screen"}],
                    []},
                   {"link",
                    [{"rel","stylesheet"},
                     {"type","text/css"},
                     {"href","/static/foo.css"},
                     {"media","screen"}],
                    []},
                   {comment,"[if lt IE 7]>\n   <style type=\"text/css\">\n     .no_ie { display: none; }\n   </style>\n   <![endif]"},
                   {"link",
                    [{"rel","icon"},
                     {"href","/static/images/favicon.ico"},
                     {"type","image/x-icon"}],
                    []},
                   {"link",
                    [{"rel","shortcut icon"},
                     {"href","/static/images/favicon.ico"},
                     {"type","image/x-icon"}],
                    []}]},
                 {"body",
                  [{"id","home"},
                   {"class","tundra"}],
                  []}]},
      Expect = parse(D0),
      ok.
  
  test_parse_tokens() ->
      D0 = [{doctype,["HTML","PUBLIC","-//W3C//DTD HTML 4.01 Transitional//EN"]},
  