public function actionNext()
 {
     $params = Yii::$app->getRequest()->getBodyParams();
     $testId = $params['testId'];
     $result = ['word' => '', 'translations' => [], 'language' => '', 'success' => false];
     $test = Test::findOne($testId);
     if (!$test) {
         // The client supplied a wrong test ID!
         $result['message'] = 'The test was not found';
         return $result;
     }
     $next = Dictionary::next($testId);
     if (!count($next)) {
         return $result;
     }
     $next['success'] = true;
     return $next;
 }