public function sendToDevice($deviceId, $openId, $content)
    {
        $params = [
            'device_type' => $this->deviceType,
            'device_id' => $deviceId,
            'open_id' => $openId,
            'content' => base64_encode($content),
        ];

        return $this->parseJSON('json', [self::API_TRANS_MSG, $params]);
    }