code: def test_python_data_source_is_pickable():
      source = python.PythonDataSource(length=42, getitem=getitem)
      source = pickle.loads(pickle.dumps(source))
      assert source[0] == 0
  
file_path: datasets/tensorflow_datasets/core/data_sources/python_test.py
imports: import pickle
  from unittest import mock
  from tensorflow_datasets.core.data_sources import python
  import tree
label_desc: Use image node_id 4 for calling a global function with example usage: test_python_data_source_is_pickable() without return types