public static function singleton()
	{
		if (!isset(self::$instance)) {
			$className = __CLASS__;
			self::$instance = new $className;
		}
		return self::$instance;
	}
 public static function singleton($salidaTipo = '', $lenguaje = '')
 {
     if (!isset(self::$instance)) {
         $className = __CLASS__;
         self::$instance = new $className($salidaTipo, $lenguaje);
     }
     return self::$instance;
 }