def safe_no_dnn_algo_bwd(algo):
    """
    Make sure the user is not attempting to use dnn.conv.algo_bwd`.
    """
    if algo:
        raise RuntimeError(
            'The option `dnn.conv.algo_bwd` has been removed and should not be used anymore. Please use the options `dnn.conv.algo_bwd_filter` and `dnn.conv.algo_bwd_data` instead.'
            )
    return True
