code: def test_class_constant(self):
      class M(torch.nn.Module):
          __constants__ = ["w"]
  
          def __init__(self, w):
              super().__init__()
              self.w = w
  
          def forward(self, x):
              # Make sure class constant is accessible in method
              y = self.w
              return x, y
  
      # Test serialization/deserialization of class constant
      for c in (2, 1.0, None, True, "str", (2, 3), [5.9, 7.3]):
          m = torch.jit.script(M(c))
          buffer = io.BytesIO()
          torch.jit.save(m, buffer)
  
          buffer.seek(0)
          m_loaded = torch.jit.load(buffer)
          input = torch.rand(2, 3)
          self.assertEqual(m(input), m_loaded(input))
          # Make sure class constant is accessible from module
          self.assertEqual(m.w, m_loaded.w)
  
imports: import io
  import os
  import sys
  import unittest
  import torch
  import torch.nn
  from torch.testing import FileCheck
  from typing import Any
  from torch.testing._internal.jit_utils import JitTestCase, make_global
  import torch.testing._internal.jit_utils
  from torch.testing._internal.common_utils import IS_SANDCASTLE, skipIfTorchDynamo
  from typing import List, Tuple, Iterable, Optional, Dict
label_desc: Use image node_id 30 for calling the TestClassType obj's underlying member method code with example usage: obj.test_class_constant() and returns: x,  y