code: def _run_trainer(self, extension, expect, optimizer=None):
      if optimizer is None:
          optimizer = self.optimizer
      extension.initialize(self.trainer)
      actual = []
      for _ in expect:
          self.trainer.updater.update()
          actual.append(optimizer.x)
          if self.trigger(self.trainer):
              extension(self.trainer)
  
      testing.assert_allclose(actual[0], expect[0])
      testing.assert_allclose(actual[1], expect[1])
      testing.assert_allclose(actual[2], expect[2])
      testing.assert_allclose(actual[3], expect[3])
      testing.assert_allclose(actual[4], expect[4])
      testing.assert_allclose(actual[5], expect[5])
  
file_path: chainer/tests/chainer_tests/training_tests/extensions_tests/test_multistep_shift.py
imports: import unittest
  import mock
  from chainer import testing
  from chainer.training import extensions
  from chainer.training import util
label_desc: Use image node_id 2 for calling the TestMutistepShift obj's underlying member method code with example usage: obj._run_trainer(extension, expect, optimizer) without return types