old_contents: def download(url, save_dir='.'):
      """Downloads trained weights and config.
  
      Args:
          url (str): target url.
          save_dir (str): store directory.
      """
      pass
  
new_contents: import io
  import os
  import zipfile
  
  import requests
  
  
  def download(url, save_dir='.'):
      """Downloads trained weights, config and preprocessor.
  
      Args:
          url (str): target url.
          save_dir (str): store directory.
      """
      print('Downloading...')
      r = requests.get(url, stream=True)
      with zipfile.ZipFile(io.BytesIO(r.content)) as f:
          if not os.path.exists(save_dir):
              os.mkdir(save_dir)
          f.extractall(save_dir)
      print('Complete!')
  
subject: Implement download method