class_docstr: Utility class used to wrap a sized stream.
  
  Objects of this class will return experiences wrapped
  using class:`ExperienceWrapper`.
code: def __len__(self):
      return len(self._wrapped_stream)
  
imports: from typing import Generic, Iterable, Iterator, List, Optional, TypeVar
  from avalanche.benchmarks.scenarios.generic_scenario import CLExperience, CLScenario, CLStream, SequenceCLStream, SizedCLStream
label_desc: Use image node_id 2 for calling the SizedCLStreamWrapper obj's underlying member method code with example usage: obj.__len__() and returns: len