Downloading a web page with 5XX retry

downloading_a_web_page.py

import urllib.request
from urllib.error import URLError, HTTPError, ContentTooShortError

def download(url, num_retries=2):
    print('Downloading:', url)
    try:
        html = urllib.request.urlopen(url).read()
    except (URLError, HTTPError, ContentTooShortError) as e:
        print('Download error:', e.reason)
        html = None
        if num_retries > 0:
            if (hasattr(e, 'code') and 500 <= e.code < 600):
                return download(url, num_retries - 1)
    return html

if __name__ == '__main__':
    html_404 = download('http://httpstat.us/404')
    print(html_404)
    html_500 = download('http://httpstat.us/500')
    print(html_500)