/**
  * Create a new subitems collection with a single subitem
  * for the specified collection with the specified HTML and page number.
  *
  * @static
  * @param Carbon_Pagination_Collection $collection Collection of the original item.
  * @param string $html HTML of the new subitem.
  * @param int $page_number The number of the page to link the subitem to.
  * @return Carbon_Pagination_Collection $subitems_collection The new subitems collection.
  */
 public static function generate_single_subitem_collection($collection, $html, $page_number)
 {
     $page_item = new Carbon_Pagination_Item_Page($collection);
     $page_item->set_html($html);
     $page_item->set_page_number($page_number);
     // create and assign the subitems collection
     $subitems_collection = new Carbon_Pagination_Collection($collection->get_pagination(), false);
     $subitems_collection->set_items(array($page_item));
     return $subitems_collection;
 }