def METHOD_NAME():
    """
    Returns a set of valid filenames that should exist
    based on the objects stored in GenerateCSVLogRequest.
    Any other files except these filenames should be removed.
    """
    valid_filenames_set = set()
    log_requests = GenerateCSVLogRequest.objects.all()
    for log_request in log_requests:
        full_path = get_filepath(
            log_request.log_type,
            log_request.facility_id,
            log_request.selected_start_date.strftime("%Y-%m-%d"),
            log_request.selected_end_date.strftime("%Y-%m-%d"),
        )
        valid_filenames_set.add(os.path.basename(full_path))
    return valid_filenames_set