/**
* Implements the Singleton pattern for this clas
*
* @staticvar extensionUpdateHelper $instance The static object instance
* @return extensionUpdateHelper
*/
public static function getInstance($extension = null, $target = null, $updateFrequency = null)
{
if (!isset(self::$instance)) {
self::$instance = new extensionUpdateHelper($extension, $target, $updateFrequency);
}
return self::$instance;
}
