code: def test_save_load_to_buf(self):
      model = linearModel()
      encrypted_buf = io.BytesIO()
      # Reference expected value
      expected_buf = io.BytesIO()
      torch.old_save(model.state_dict(), expected_buf)
      expected_buf.seek(0)
      expected_state = torch.load(expected_buf)
      torch.save(
          model.state_dict(),
          encrypted_buf,
          encryption_key=encryption_key,
      )
      # load it back and compare the stat_dict is the same
      our_state_dict = torch.load(
          encrypted_buf, decryption_key=encryption_key
      )
      self.assertEqual(our_state_dict, expected_state)
  
imports: import torch.nn.functional
  import torch, os, io
  import base64
  import torch.nn
  import unittest
  import random
  from bigdl.nano.pytorch.patching import patch_encryption
  import torch.optim
label_desc: Use image node_id 2 for calling the TestModelSaveLoad obj's underlying member method code with example usage: obj.test_save_load_to_buf() without return types