/**
  * @param  $atts array inputs
  * @return string shortcode content
  */
 public function handleShortcode($atts)
 {
     if (!isset($atts["id"])) {
         $entries = Entry::fetchAll();
     } else {
         $entries = [Entry::find_one($atts["id"])];
     }
     $collections = $this->buildCollections($entries);
     $exportedHTML = '';
     foreach ($collections as $collection) {
         $exportedHTML .= $collection->export();
     }
     return $exportedHTML;
 }