public function products(Request $request)
 {
     $limit = $request->input('limit');
     $page = $request->input('page');
     //        print_r($request->input());
     //        echo(is_numeric($limit)==false);
     //        echo($limit.$page);
     if ($limit != null && $page != null && count($request->input()) == 2 && is_numeric($limit) == true && is_numeric($page) == true) {
         $todos = ProductModel::paginate($limit);
         return ['message' => 'OK', 'state' => 'list of all products', 'result' => $todos->toArray()];
     } else {
         return response('Invalid Argument', 400);
     }
 }