function modify( &$tpl, &$operatorName, &$operatorParameters, &$rootNamespace,
                     &$currentNamespace, &$operatorValue, &$namedParameters )
    {
       switch ( $operatorName )
       {
            case 'opengraph':
            {
                $operatorValue = $this->generateOpenGraphTags( $namedParameters['nodeid'] );
                break;
            }
            case 'language_code':
            {
                $operatorValue = eZLocale::instance()->httpLocaleCode();
                break;
            }
       }
    }