/**
  * Main Custom Product Tabs Lite Instance, ensures only one instance is/can be loaded
  *
  * @since 1.4.0
  * @see wc_custom_product_tabs_lite()
  * @return WooCommerceCustomProductTabsLite
  */
 public static function instance()
 {
     if (is_null(self::$instance)) {
         self::$instance = new self();
     }
     return self::$instance;
 }