anchor.diff:          undefined -> MD#url_metadata.final_url;
           PrefUrl -> z_url:abs_link(PrefUrl, MD#url_metadata.final_url)
       end;
  +p(content_length, MD) ->
  +    MD#url_metadata.content_length;
  +p(content_type, MD) ->
  +    MD#url_metadata.content_type;
  +p(headers, MD) ->
  +    MD#url_metadata.headers;
   p(title, MD) ->
       case p1([<<"og:title">>, <<"twitter:title">>, mtitle, h1, title], MD) of
           undefined -> p(filename, MD);
  
positive.code:                         Acc;
                      [_] ->
                          Acc;
                      [Name, <<$=, Value/binary>>] ->
                          [{z_string:to_lower(z_string:trim(Name)),
                            unquote_header(z_string:trim(Value))} | Acc]
                  end
  
negative.code:     end;
  p(filename, MD) ->
      filename(MD#url_metadata.final_url, MD#url_metadata.headers);
  p(Ks, MD) when is_list(Ks) ->
      p1(Ks, MD);
  p(K, MD) ->
  