code: def _test_checkpoint(self, optimizer_states):
      for epoch, epoch_optimizer_state in optimizer_states.items():
          filename = self.checkpoint_filename.format(epoch=epoch)
          self.model.load_optimizer_state(filename)
          saved_optimizer_state = torch_to_numpy(
              self.optimizer.state_dict()
          )
  
          self.assertEqual(epoch_optimizer_state, saved_optimizer_state)
  
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 7 for calling the OptimizerCheckpointTest obj's underlying member method code with example usage: obj._test_checkpoint(optimizer_states) without return types