code: def _slice_collate(
      classes_in_exps: Iterable[Optional[Iterable[int]]],
  ) -> Optional[Tuple[Set[int], ...]]:
      result: List[Set[int]] = []
      for x in classes_in_exps:
          if x is None:
              return None
          result.append(set(x))
  
      return tuple(result)
  
imports: from typing import Callable, TypeVar, Union, Sequence, Optional, Iterable, List, Set, Tuple, Mapping, overload, TYPE_CHECKING
  import warnings
  from avalanche.benchmarks.scenarios.deprecated import AbstractClassTimelineExperience
  from avalanche.benchmarks.scenarios.deprecated.dataset_scenario import ClassesTimelineCLScenario, FactoryBasedStream, TStreamsUserDict
  from avalanche.benchmarks.utils.dataset_utils import manage_advanced_indexing
label_desc: Use image node_id 8 for calling the _LazyClassesInClassificationExps obj's underlying member method code with example usage: obj._slice_collate(classes_in_exps) and returns: tuple, None