def after_training_exp(self, strategy, **kwargs):
        """
        Save a copy of the model after each experience
        and freeze the prev model and freeze the last layer of current model
        """

        self.prev_model = copy.deepcopy(strategy.model)

        freeze_everything(self.prev_model)

        last_fc_name, last_fc = get_last_fc_layer(strategy.model)

        for param in last_fc.parameters():
            param.requires_grad = False

        Save a copy of the model after each experience
        and freeze the prev model and freeze the last layer of current model
        
avalanche/training/plugins/lfl.py