/**
  * Gets tags from this group
  *
  * @return array
  */
 public function get_tags()
 {
     if (!is_array($this->tags)) {
         require_once dirname(__FILE__) . '/Tags.class.php';
         $tags_list = new Tags_list();
         $this->tags = $tags_list->get_tags_by_group_id($this->id);
         if (!is_array($this->tags)) {
             $this->tags = array();
         }
     }
     return $this->tags;
 }