Returns tuple with download progress (for optional DLCs):

            (bytes_downloaded, bytes_total)

        :rtype: tuple

def get_download_progress(self):
        """Returns tuple with download progress (for optional DLCs):

            (bytes_downloaded, bytes_total)

        :rtype: tuple
        """
        downloaded = CRef.cint()
        total = CRef.cint()

        result = self._iface.get_dlc_download_progress(self.app_id, downloaded, total)

        if not result:
            return 0, 0

        return int(downloaded), int(total)