public function removeSubscribers($subscribers)
    {
        $subscribers = AnConfig::unbox($subscribers);

        if (is($subscribers, 'AnDomainEntityAbstract')) {
            $subscribers = array($subscribers);
        } else {
            $subscribers = (array) $subscribers;
        }

        $ids = $this->subscriberIds->toArray();

        foreach ($subscribers as $subscriber) {
            $id = is($subscriber, 'AnDomainEntityAbstract') ? $subscriber->id : $subscriber;
            unset($ids[$id]);
        }

        $this->set('subscriberIds', AnDomainAttribute::getInstance('set')->setData($ids));

        //if there are no more subscriber then delete the notification
        if (empty($ids)) {
            $this->delete();
        }

        return $this;
    }