public static function getDebugTag( $element ) {
		if ( !$element ) {
			return '';
		} elseif ( $element instanceof Element || $element instanceof SerializerNode ) {
			return $element->getDebugTag();
		} else {
			return get_class( $element ) . '#' . substr( md5( spl_object_hash( $element ) ), 0, 8 );
		}
	}