public function info($mchBillno)
    {
        $params = is_array($mchBillno) ? $mchBillno : ['mch_billno' => $mchBillno];
        $base = [
            'appid' => $this->app['config']->app_id,
            'bill_type' => 'MCHT',
        ];

        return $this->safeRequest('mmpaymkttransfers/gethbinfo', array_merge($base, $params));
    }