private function _replace_label($full_match, $opening_tag, $label_inner, $closing_tag, $template)
 {
     $OpeningTag = new PerchXMLTag($opening_tag);
     $attrs = array();
     $attrs['id'] = $OpeningTag->id();
     $attrs['class'] = $OpeningTag->class();
     $attrs['for'] = $this->field_prefix . $OpeningTag->for();
     $new_opening_tag = PerchXMLTag::create('label', 'opening', $attrs);
     $template = str_replace($opening_tag, $new_opening_tag, $template);
     $new_closing_tag = PerchXMLTag::create('label', 'closing');
     $template = str_replace($closing_tag, $new_closing_tag, $template);
     return $template;
 }