code: def _create_mock_trainer(self, iterations):
      trainer = testing.get_trainer_with_mock_updater(
          (iterations, "iteration")
      )
      trainer.updater.update_core = lambda: time.sleep(0.001)
      return trainer
  
imports: import time
  import traceback
  import unittest
  from chainer import testing
  from chainer import training
label_desc: Use image node_id 2 for calling the TestTrainer obj's underlying member method code with example usage: obj._create_mock_trainer(iterations) and returns: trainer