/**
  * Destroy the singleton instance to let a subsequent call create a new
  * one. This should NEVER be used on non CLI interface, that will throw an
  * internal error.
  */
 public static function destroySingleton()
 {
     if (PHP_SAPI !== 'cli') {
         self::error('Can not destroy singleton instance when used ' . 'with non-CLI interface');
     }
     self::$instance = null;
 }