def classes_in_experience(
        self,
    ) -> Mapping[str, Sequence[Optional[Set[int]]]]:
        """
        A dictionary mapping each stream (by name) to a list.

        Each element of the list is a set describing the classes included in
        that experience (identified by its index).

        In previous releases this field contained the list of sets for the
        training stream (that is, there was no way to obtain the list for other
        streams). That behavior is deprecated and support for that usage way
        will be removed in the future.
        """
        pass

        A dictionary mapping each stream (by name) to a list.

        Each element of the list is a set describing the classes included in
        that experience (identified by its index).

        In previous releases this field contained the list of sets for the
        training stream (that is, there was no way to obtain the list for other
        streams). That behavior is deprecated and support for that usage way
        will be removed in the future.
        
avalanche/benchmarks/scenarios/deprecated/dataset_scenario.py