code: def test_LongDataFrameDataset_iter(long_dataset):
      for i in long_dataset:
          assert isinstance(i, dict)
          assert "start" in i
          assert "target" in i
          assert "feat_dynamic_real" in i
  
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 6 for calling a global function with example usage: test_LongDataFrameDataset_iter(long_dataset) without return types