public function prependEmpty($text=NULL) {
		
		$t = Translator::getInstance();
		
		$option			= new \stdClass();
		$option->value	= '';
		$option->text	= is_null($text) ? $t->get('SELECT_NULL_VALUE') : $text;

		$this->list = array_merge(array($option), $this->list);
		
		return $this;
		
	}