public function triggerGroup(?array $events = [], ?array $args = null)
  {
    foreach($events as $callback) {
      if (is_callable($callback)) {
        call_user_func_array($callback, isset($args) ? $args : []);
      }
      else if (is_string($callback)) {
        $call = new $callback;
        call_user_func_array([$call, 'persist'], $args ?? []);
      }
    }
  }