public static function config($config = []) {
		if (!$config) {
			return ['rules' => static::$_rules];
		}
		foreach ($config as $key => $val) {
			if (isset(static::${'_' . $key})) {
				static::${'_' . $key} = $val + static::${'_' . $key};
			}
		}
	}