code: def test_backport_bytecode_from_file_to_buffer(self):
      maximum_checked_in_model_version = max(
          SCRIPT_MODULE_BYTECODE_PKL.keys()
      )
      script_module_v5_path = (
          pytorch_test_dir
          / "cpp"
          / "jit"
          / SCRIPT_MODULE_BYTECODE_PKL[
              maximum_checked_in_model_version
          ]["model_name"]
      )
  
      if maximum_checked_in_model_version > MINIMUM_TO_VERSION:
          # Backport model to v4
          script_module_v4_buffer = _backport_for_mobile_to_buffer(
              script_module_v5_path,
              maximum_checked_in_model_version - 1,
          )
          buf = io.StringIO()
  
          # Check version of the model v4 from backport
          bytesio = io.BytesIO(script_module_v4_buffer)
          backport_version = _get_model_bytecode_version(bytesio)
          assert (
              backport_version == maximum_checked_in_model_version - 1
          )
  
          # Load model v4 from backport and run forward method
          bytesio = io.BytesIO(script_module_v4_buffer)
          mobile_module = _load_for_lite_interpreter(bytesio)
          module_input = 1
          mobile_module_result = mobile_module(module_input)
          expected_mobile_module_result = 3 * torch.ones(
              [2, 4], dtype=torch.float64
          )
          torch.testing.assert_close(
              mobile_module_result, expected_mobile_module_result
          )
  
file_path: pytorch/test/mobile/test_bytecode.py
imports: import fnmatch
  import io
  import shutil
  import tempfile
  import torch
  import torch.utils.show_pickle
  from torch.jit.mobile import _load_for_lite_interpreter, _get_mobile_model_contained_types, _get_model_bytecode_version, _get_model_ops_and_info, _backport_for_mobile_to_buffer, _backport_for_mobile
  from torch.testing._internal.common_utils import TestCase, run_tests
  from pathlib import Path
label_desc: Use image node_id 4 for calling the testVariousModelVersions obj's underlying member method code with example usage: obj.test_backport_bytecode_from_file_to_buffer() without return types