def __init__(self, current_metric: TMetric):
        """
        Creates an instance of the GenericExperienceForwardTransfer metric.
        """

        super().__init__()

        self.forward_transfer = ForwardTransfer()
        """
        The general metric to compute forward transfer
        """

        self._current_metric: TMetric = current_metric
        """
        The metric the user should override
        """

        self.eval_exp_id: int = -1
        """
        The current evaluation experience id
        """

        self.train_exp_id = None
        """
        The last encountered training experience id
        """

        self.at_init = True

        Creates an instance of the GenericExperienceForwardTransfer metric.
        
avalanche/evaluation/metrics/forward_transfer.py