code: def tearDownClass(cls):
      cls.sc.stop()
  
imports: import pyspark
  from pyspark import SparkContext
  from absl.testing import parameterized
  from unittest.mock import patch
  import unittest
  import sys
  import collections
  import pipeline_dp
  from pipeline_dp import aggregate_params
  from pipeline_dp import budget_accounting, private_spark
label_desc: Use image node_id 23 for calling the PrivateRDDTest obj's underlying member method code with example usage: obj.tearDownClass(cls) without return types