anchor.diff:                  end,
               case classify(URL, Hostname, IsIP) of
                   {ok, ClassName} ->
  -                    case get_class_redirect_url(ClassName) of
  -                        {ok, RedirectURL} ->
  -                            {ok, ClassName, RedirectURL};
  -                        _ -> undefined
  -                    end;
  +                    {ok, ClassName,
  +                     get_class_redirect_url(ClassName)};
                   _ -> undefined
               end;
           _ -> undefined
  
positive.code: 
  get_class_redirect_url(ClassName) ->
      case ets:lookup(?FAC_DOMAINS, {url, ClassName}) of
          [{_, [_ | _] = URL}] -> {ok, URL};
          _ -> undefined
      end.
  
  
negative.code:         _ -> undefined
      end;
  classify_(_URL, Domain, _IsIP = false) ->
      classify_domain(string:tokens(Domain, ".")).
  
  classify_domain([_ | Tail] = Tokens) ->
      Domain = string:join(Tokens, "."),
      case ets:lookup(?FAC_DOMAINS, Domain) of
          [{_, ClassName}] -> {ok, ClassName};
          _ -> classify_domain(Tail)
  