code: def testNestedContexts(self):
      with MyContext() as ctx1:
          with DefaultMyContext() as ctx2:
              self.assertEqual(DefaultMyContext.current(), ctx2)
              self.assertEqual(MyContext.current(), ctx1)
  
file_path: pytorch/caffe2/python/context_test.py
imports: from caffe2.python import context, test_util
  from threading import Thread
label_desc: Use image node_id 6 for calling the TestContext obj's underlying member method code with example usage: obj.testNestedContexts() without return types