code: def test_forward_missing_attributes(self):
      lin = nn.Linear(1, 1)
      m = nn.Sequential(lin, lin)
      wrapped = CheckpointWrapper(m)
      # Test indexing is forwarded
      self.assertEqual(wrapped[0], lin)
      # Test missing attributes are forwarded.
      m._foo = "bar"
      self.assertEqual(wrapped._foo, "bar")
  
file_path: pytorch/test/distributed/fsdp/test_checkpoint_wrapper.py
imports: import contextlib
  import unittest
  from copy import deepcopy
  from functools import partial
  import torch
  import torch.nn
  from torch.distributed.algorithms._checkpoint.checkpoint_wrapper import apply_activation_checkpointing, checkpoint_wrapper, CheckpointImpl, CheckpointWrapper, offload_wrapper, OffloadWrapper
  from torch.distributed.fsdp.wrap import ModuleWrapPolicy
  from torch.testing._internal.common_utils import run_tests, TestCase
  from torch.utils.checkpoint import checkpoint
label_desc: Use image node_id 5 for calling the CheckpointWrapperTest obj's underlying member method code with example usage: obj.test_forward_missing_attributes() without return types