code: def _test_batch_size(self, loader, expected_size=None):
      if expected_size is None:
          expected_size = self._batch_size * 2
  
      for batch in loader:
          self.assertEqual(len(batch[0]), expected_size)
  
file_path: avalanche/tests/benchmarks/utils/test_replay_loader.py
imports: import unittest
  import numpy
  from avalanche.benchmarks.classic import SplitMNIST
  from avalanche.benchmarks.utils.data_loader import ReplayDataLoader
label_desc: Use image node_id 3 for calling the TestReplayDataLoader obj's underlying member method code with example usage: obj._test_batch_size(loader, expected_size) without return types