protected function _meta($features = null, array $options = []) {
        if ($features) {
            $features = join(',', array_map(function($item) {
                        return '_' . strtolower(trim($item, '_'));
                    }, is_scalar($features) ? explode(",", $features) : $features));
        }
        $options = ['index' => $this->index()] + $options + ($features ? ['feature' => $features] : []);
        $result = $this->client->indices()->get($options);
        $result = array_pop($result);
        return $result;
    }