code: def __init__(self, size, step):
      self.size = size
      self.step = step
      self.counter = 0
  
file_path: pytorch-lightning/tests/tests_data/streaming/test_combined.py
imports: import pytest
  from lightning.data.streaming.combined import CombinedStreamingDataset
  from torch.utils.data import IterableDataset
label_desc: Use image node_id 1 to create a new TestStatefulDataset object  with example: obj = TestStatefulDataset(size, step)