code: def test_elapsed_time_serialization(self):
      self.trainer.run()
      serialized_time = self.trainer.elapsed_time
  
      new_trainer = self._create_mock_trainer(5)
      testing.save_and_load_npz(self.trainer, new_trainer)
  
      new_trainer.run()
      self.assertGreater(new_trainer.elapsed_time, serialized_time)
  
imports: import time
  import traceback
  import unittest
  from chainer import testing
  from chainer import training
label_desc: Use image node_id 4 for calling the TestTrainer obj's underlying member method code with example usage: obj.test_elapsed_time_serialization() without return types