/**
  * Fetches the Singleton object
  *
  * @param string $class_name
  *
  * @return Yoast_GA_Admin_Custom_Dimensions
  */
 public static function get_instance($class_name = __CLASS__)
 {
     if (is_null(self::$instance)) {
         self::$instance = new $class_name();
     }
     return self::$instance;
 }
 /**
  * Overrides instance to set with this class as class
  *
  * @param string $class_name
  *
  * @return Yoast_GA_Custom_Definitions
  */
 public static function get_instance($class_name = __CLASS__)
 {
     return parent::get_instance($class_name);
 }