code: def test_LongDataFrameDataset_len(long_dataset):
      assert len(long_dataset) == 2
  
imports: import io
  from typing import Callable, List, Union
  import pandas
  import numpy
  import pytest
  from gluonts.dataset import pandas
  from gluonts.testutil.equality import assert_recursively_equal
label_desc: Use image node_id 7 for calling a global function with example usage: test_LongDataFrameDataset_len(long_dataset) without return types