code: def tearDownClass(cls):
      cls.pool.terminate()
      cls.pool.join()
      cls.pool = None
      super().tearDownClass()
  
imports: from mpi4py import MPI
  import mpi4py.util.pool
  import concurrent.futures
  import itertools
  import functools
  import warnings
  import unittest
  import time
  import sys
  import os
label_desc: Use image node_id 3 for calling the BaseTestPool obj's underlying member method code with example usage: obj.tearDownClass(cls) without return types