public function getElementsBy($property, $value)
 {
     $elems_a = parent::getElementsBy($property, $value);
     foreach ($this->_elements as $element) {
         $sub_elems_a = $element->getElementsBy($property, $value);
         foreach ($sub_elems_a as $match) {
             $elems_a[] = $match;
         }
     }
     return $elems_a;
 }