/**
  * Gets an instance of a factory object to return on subsequent calls of getInstance.
  *
  * @param   FOFDatabaseFactory  $instance  A FOFDatabaseFactory object.
  *
  * @return  void
  *
  * @since   12.1
  */
 public static function setInstance(FOFDatabaseFactory $instance = null)
 {
     self::$_instance = $instance;
 }