public static function boot()
    {
        parent::boot();

        self::saving(function($model)
        {
            return $model->beforeSave();
        });

        self::saved(function($model)
        {
            return $model->afterSave();
        });

        self::deleting(function($model)
        {
            return $model->beforeDelete();
        });

        self::deleted(function($model)
        {
            return $model->afterDelete();
        });
    }