code: def serialized_file(work_dir):
      model_url = ResNet18_Weights.DEFAULT.url
  
      download_model(model_url, work_dir)
  
      yield Path(work_dir) / "model.pt"
  
imports: import asyncio
  import json
  import random
  import shutil
  from pathlib import Path
  from unittest.mock import patch
  from zipfile import ZIP_STORED, ZipFile
  import pytest
  import requests
  import test_utils
  import yaml
  from model_archiver import ModelArchiverConfig
  from torchvision.models.resnet import ResNet18_Weights
  from ts.torch_handler.unit_tests.test_utils.model_dir import download_model
label_desc: Use image node_id 7 for calling a global function with example usage: serialized_file(work_dir) without return types