code: def test_post_forward_hook_is_executed(self):
      test_model = ModelForTest()
      x = torch.randn(2, 3)
      output = test_model(x)
  
      test_hook = PostForwardHook()
      add_hook_to_module(test_model, test_hook)
      output1 = test_model(x)
      self.assertTrue(torch.allclose(output1, output + 1, atol=1e-5))
  
      # Attaching a hook to a model when it already has one replaces, does not chain
      test_hook = PostForwardHook()
      add_hook_to_module(test_model, test_hook)
      output1 = test_model(x)
      self.assertTrue(torch.allclose(output1, output + 1, atol=1e-5))
  
      # You need to use the sequential hook to chain two or more hooks
      test_hook = SequentialHook(PostForwardHook(), PostForwardHook())
      add_hook_to_module(test_model, test_hook)
  
      output2 = test_model(x)
      assert torch.allclose(output2, output + 2, atol=1e-5)
  
imports: import inspect
  import unittest
  import torch
  import torch.nn
  from accelerate.hooks import AlignDevicesHook, ModelHook, SequentialHook, add_hook_to_module, attach_align_device_hook, remove_hook_from_module, remove_hook_from_submodules
  from accelerate.test_utils import require_multi_gpu
label_desc: Use image node_id 4 for calling the HooksModelTester obj's underlying member method code with example usage: obj.test_post_forward_hook_is_executed() without return types