Modx Revolution - Article 7.1 Addone - issue: how to remove / at end of the url

$string = $modx->getOption('string',$scriptProperties,'');
$delimiter = $modx->getOption('delimiter',$scriptProperties,',');
$tpl = $modx->getOption('tpl',$scriptProperties,'articlerssitem');
$outputSeparator = $modx->getOption('outputSeparator',$scriptProperties,"\n");
$outputSeparator = str_replace('\\n',"\n",$outputSeparator);
$toPlaceholder = $modx->getOption('toPlaceholder',$scriptProperties,'');

$items = explode($delimiter,$string);
$items = array_unique($items);
$list = array();
foreach ($items as $item) {
    $list[] = $modx->getChunk($tpl,array(
        'item' => $item,
    ));
}

$output = implode($outputSeparator,$list);
if (!empty($toPlaceholder)) {
    $modx->setPlaceholder($toPlaceholder,$output);
    return '';
}
return $output;

$modx->lexicon->load('articles:frontend');

$container = $modx->getOption('container',$scriptProperties,0);
if (empty($container)) return '';
/** @var ArticlesContainer $container */
$container = $modx->getObject('ArticlesContainer',$container);
if (empty($container)) return '';

$placeholderPrefix = $modx->getOption('placeholderPrefix',$scriptProperties,'');

$container->getPostListingCall($placeholderPrefix);
$container->getArchivistCall($placeholderPrefix);
$container->getTagListerCall($placeholderPrefix);
$container->getLatestPostsCall($placeholderPrefix);
$settings = $container->getContainerSettings();
if ($modx->getOption('commentsEnabled',$settings,true)) {
    $container->getLatestCommentsCall($placeholderPrefix);
    $modx->setPlaceholder($placeholderPrefix.'comments_enabled',1);
} else {
    $modx->s