public ResponseModel <GroupModel> GetById(int id)
        {
            var resp = new ResponseModel <GroupModel>();

            try
            {
                var app = AppRepo.GetGroupModelById(id);

                if (app != null)
                {
                    resp.Data        = app;
                    resp.Status      = 200;
                    resp.Description = "OK";
                }
                else
                {
                    resp.Status      = 200;
                    resp.Data        = null;
                    resp.Description = "Group not found";
                }
            }
            catch (Exception ex)
            {
                resp.Status      = 500;
                resp.Description = $"Error: {ex.Message}";
                resp.Data        = null;
            }

            return(resp);
        }