protected function post($endpoint, array $params = [], $fileUpload = false)
    {
        if ($fileUpload) {
            $params = ['multipart' => $params];
        } else {

            if (array_key_exists('reply_markup', $params)) {
                $params['reply_markup'] = (string)$params['reply_markup'];
            }

            $params = ['form_params' => $params];
        }

        return $this->sendRequest(
            'POST',
            $endpoint,
            $params
        );
    }