code: def maybe_download_from_drive(directory, filename, url):
    
    if not tf.gfile.Exists(directory):
      tf.logging.info("Creating directory %s" % directory)
      tf.gfile.MakeDirs(directory)
    filepath = os.path.join(directory, filename)
    confirm_token = None
    if tf.gfile.Exists(filepath):
      tf.logging.info("Not downloading, file already found: %s" % filepath)
      return filepath
  
    # Since the file is big, drive will scan it for virus and take it to a
    # warning page. We find the confirm token on this page and append it to the
    # URL to start the download process.
    confirm_token = None
    session = requests.Session()
    response = session.get(url, stream=True)
    for k, v in response.cookies.items():
      if k.startswith("download_warning"):
        confirm_token = v
  
    if confirm_token:
      url = url + "&confirm=" + confirm_token
    tf.logging.info("Downloading %s to %s" % (url, filepath))
  
    response = session.get(url, stream=True)
    # Now begin the download.
    chunk_size = 16 * 1024
    with open(filepath, "wb") as f:
      for chunk in response.iter_content(chunk_size):
        if chunk:
          f.write(chunk)
  
    # Print newline to clear the carriage return from the download progress
    print()
    statinfo = os.stat(filepath)
    tf.logging.info("Successfully downloaded %s, %s bytes." % (filename,
                                                               statinfo.st_size))
    return filepath
docs: Download filename from Google drive unless it's already in directory.
  
    Args:
      directory: path to the directory that will be used.
      filename: name of the file to download to (do nothing if it already exists).
      url: URL to download from.
  
    Returns:
      The path to the downloaded file.