code: def tearDown(self):
      sentinel._cache.clear()
  
file_path: zipline/tests/utils/test_sentinel.py
imports: from copy import copy, deepcopy
  from pickle import loads, dumps
  import sys
  from unittest import TestCase
  from weakref import ref
  from zipline.utils.sentinel import sentinel
label_desc: Use image node_id 1 for calling the SentinelTestCase obj's underlying member method code with example usage: obj.tearDown() without return types