public function init()
{
parent::init();
$this->on(self::EVENT_BEFORE_INSERT, [$this, 'beforeSaveTree']);
$this->on(self::EVENT_BEFORE_UPDATE, [$this, 'beforeSaveTree']);
$this->on(self::EVENT_AFTER_UPDATE, [$this, 'afterUpdateTree']);
$this->on(self::EVENT_BEFORE_DELETE, [$this, 'beforeDeleteTree']);
$this->on(self::EVENT_AFTER_DELETE, [$this, 'afterDeleteTree']);
}