public function handleRequestException(AphrontRequest $request, Exception $ex)
 {
     $viewer = $this->getViewer($request);
     return id(new AphrontDialogView())->setTitle(pht('Slow Down!'))->setUser($viewer)->setErrors(array(pht('You are being rate limited.')))->appendParagraph($ex->getMessage())->appendParagraph($ex->getRateExplanation())->addCancelButton('/', pht('Okaaaaaaaaaaaaaay...'));
 }