/**
  * Perform request
  * 
  * @param  string $url
  * @return json   
  */
 private function request($url)
 {
     $request = new Request($this->apiKey, $url);
     $request->send();
     if ($request->fails()) {
         throw new ZomatoException("cURL error: {$request->getError()}");
     }
     return $request->getResult();
 }