code: def tearDownClass(cls):
      cls._stack.close()
  
file_path: catalyst/tests/pipeline/test_column.py
imports: from contextlib2 import ExitStack
  from unittest import TestCase
  from pandas import date_range, DataFrame
  from pandas.util.testing import assert_frame_equal
  from catalyst.lib.labelarray import LabelArray
  from catalyst.pipeline import Pipeline
  from catalyst.pipeline.data.testing import TestingDataSet
  from catalyst.testing import chrange, temp_pipeline_engine
  from catalyst.utils.pandas_utils import ignore_pandas_nan_categorical_warning
label_desc: Use image node_id 2 for calling the LatestTestCase obj's underlying member method code with example usage: obj.tearDownClass(cls) without return types