Prints some download progress information
        :param blocknum:
        :param blocksize:
        :param totalsize:
        :return:

def __on_download_progress_update(self, blocknum, blocksize, totalsize):
        """
        Prints some download progress information
        :param blocknum:
        :param blocksize:
        :param totalsize:
        :return:
        """
        if not self.__show_download_progress:
            return

        readsofar = blocknum * blocksize
        if totalsize > 0:
            s = "\r%s / %s" % (size(readsofar), size(totalsize))
            sys.stdout.write(s)
            if readsofar >= totalsize:  # near the end
                sys.stderr.write("\r")
        else:  # total size is unknown
            sys.stdout.write("\rread %s" % (size(readsofar)))