anchor.diff:      lists:reverse(Acc);
   to_html([{'=', Content} | Rest], Acc) ->
       to_html(Rest, [Content | Acc]);
  +to_html([{pi, Tag, Attrs} | Rest], Acc) ->
  +    Open = ["<?" ++ Tag,
  +            attrs_to_html(Attrs, []),
  +            "?>"],
  +    to_html(Rest, [Open | Acc]);
   to_html([{comment, Comment} | Rest], Acc) ->
       to_html(Rest, [["<!--" ++ Comment, "-->"] | Acc]);
   to_html([{doctype, Parts} | Rest], Acc) ->
  
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:     {lists:reverse(Acc), [], S};
  tokenize_attributes(Rest=">" ++ _, S, Acc) ->
      {lists:reverse(Acc), Rest, S};
  tokenize_attributes(Rest="?>" ++ _, S, Acc) ->
      {lists:reverse(Acc), Rest, S};
  tokenize_attributes(Rest="/" ++ _, S, Acc) ->
      {lists:reverse(Acc), Rest, S};
  tokenize_attributes([C | Rest], S, Acc) when ?IS_WHITESPACE(C) ->
  