code: def test_integration(self):
      train_gen = some_data_generator(
          OptimizerCheckpointTest.batch_size
      )
      valid_gen = some_data_generator(
          OptimizerCheckpointTest.batch_size
      )
      checkpointer = OptimizerCheckpoint(
          self.checkpoint_filename, period=1
      )
      self.model.fit_generator(
          train_gen,
          valid_gen,
          epochs=OptimizerCheckpointTest.epochs,
          steps_per_epoch=5,
          callbacks=[checkpointer],
      )
  
file_path: poutyne/tests/framework/callbacks/test_optimizer_checkpoint.py
imports: import os
  import unittest
  from tempfile import TemporaryDirectory
  from unittest import TestCase
  import torch
  import torch.nn
  from poutyne import Model, OptimizerCheckpoint, torch_to_numpy
  from tests.framework.tools import some_data_generator
label_desc: Use image node_id 3 for calling the OptimizerCheckpointTest obj's underlying member method code with example usage: obj.test_integration() without return types