def _to_human_readable_size(bytes_, units=None):
    """Convert bytes to a human readable size."""
    units = [" bytes", "KB", "MB", "GB", "TB"] if units is None else units
    return (
        str(bytes_) + units[0]
        if bytes_ < 1024
        else _to_human_readable_size(bytes_ >> 10, units[1:])
    )