/**
  *
  * @param Exercise $exercise
  * @return mixed
  * @throws \Exception
  */
 public function destroy(Exercise $exercise = null)
 {
     //        if(is_null($exercise)) {
     //            return response([
     //                'error' => 'Exercise not found.',
     //                'status' => Response::HTTP_NOT_FOUND // = 404
     //            ], Response::HTTP_NOT_FOUND);
     //        }
     $exercise->delete();
     return $this->responseNoContent();
 }