def bwt_metrics(*, experience=False, stream=False) -> List[PluginMetric]:
    """
    Helper method that can be used to obtain the desired set of
    plugin metrics.

    :param experience: If True, will return a metric able to log
        the backward transfer on each evaluation experience.
    :param stream: If True, will return a metric able to log
        the backward transfer averaged over the evaluation stream experiences
        which have been observed during training.
    :return: A list of plugin metrics.
    """

    metrics: List[PluginMetric] = []

    if experience:
        metrics.append(ExperienceBWT())

    if stream:
        metrics.append(StreamBWT())

    return metrics

    Helper method that can be used to obtain the desired set of
    plugin metrics.

    :param experience: If True, will return a metric able to log
        the backward transfer on each evaluation experience.
    :param stream: If True, will return a metric able to log
        the backward transfer averaged over the evaluation stream experiences
        which have been observed during training.
    :return: A list of plugin metrics.
    
avalanche/evaluation/metrics/forgetting_bwt.py