anchor.diff:  %% @spec parse_tokens([html_token()]) -> html_node()
   %% @doc Transform the output of tokens(Doc) into a HTML tree.
   parse_tokens(Tokens) when is_list(Tokens) ->
  -    %% Skip over doctype
  +    %% Skip over doctype, processing instructions
       F = fun (X) ->
                   case X of
                       {start_tag, _, _, false} ->
  
positive.code:     tokenize_doctype(Rest, ?ADV_COL(S, 10), []);
  tokenize("<![CDATA[" ++ Rest, S) ->
      tokenize_cdata(Rest, ?ADV_COL(S, 9), []);
  tokenize("&" ++ Rest, S) ->
      tokenize_charref(Rest, ?INC_COL(S), []);
  tokenize("</" ++ Rest, S) ->
  
negative.code:     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={pi, _Tag, _Attrs} | Rest], S) ->
      tree(Rest, append_stack_child(T, S));
  tree([T={comment, _Comment} | Rest], S) ->
      tree(Rest, append_stack_child(T, S));
  tree(L=[{data, _Data, _Whitespace} | _], S) ->
  