code: def test_combined_dataset_normalizes_weights(weights, expected):
      combined_dataset = CombinedStreamingDataset(
          [[1], [2, 3]], weights=weights, seed=1
      )
      assert combined_dataset._weights == expected
  
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 3 for calling a global function with example usage: test_combined_dataset_normalizes_weights(weights, expected) without return types