code: def test_add_callable_class_extension(self):
      dummy_callable_class = DummyCallableClass(self)
      self.trainer.extend(dummy_callable_class)
      self.trainer.run()
      self.assertTrue(dummy_callable_class.is_called)
      self.assertTrue(dummy_callable_class.is_finalized)
  
imports: import time
  import traceback
  import unittest
  from chainer import testing
  from chainer import training
label_desc: Use image node_id 6 for calling the TestTrainer obj's underlying member method code with example usage: obj.test_add_callable_class_extension() without return types