human
I wrote the below code

    dest_directory = FLAGS.model_dir
    if (not os.path.exists(dest_directory)):
        os.makedirs(dest_directory)
    filename = DATA_URL.split('/')[(-1)]
    filepath = os.path.join(dest_directory, filename)
    if (not os.path.exists(filepath)):
        def _progress(count, block_size, total_size):
            sys.stdout.write(('\r>>    Downloading    %s    %.1f%%' % (filename, ((float((count * block_size)) / float(total_size)) * 100.0))))
            sys.stdout.flush()
        (filepath, _) = urllib.request.urlretrieve(DATA_URL, filepath, _progress)
        print()
        statinfo = os.stat(filepath)
        print('Successfully    downloaded', filename, statinfo.st_size, 'bytes.')
    tarfile.open(filepath, 'r:gz').extractall(dest_directory)

What's a good function header?
assistant
#Here's a good function header.

def maybe_download_and_extract():