def METHOD_NAME(days=None):
    """
    Upload all thumbnail and original files for preview entries to object
    storage.
    """
    query = PreviewFile.query
    if days is not None:
        limit_date = date_helpers.get_date_from_now(int(days))
        query = query.filter(PreviewFile.updated_at >= limit_date)
    for preview_file in query.all():
        upload_preview(preview_file)