public static function writeFullElement($xw, $tag, $attributes, $content)
 {
     $xw->startElement($tag);
     if (!is_null($attributes)) {
         foreach ($attributes as $name => $value) {
             $xw->writeAttribute($name, $value);
         }
     }
     if (is_array($content)) {
         foreach ($content as $values) {
             OMB_Plain_XRDS_Writer::writeFullElement($xw, $values[0], $values[1], $values[2]);
         }
     } else {
         $xw->text($content);
     }
     $xw->fullEndElement();
 }