Fix urllib for Python 2 and 3

fix_urllib.py

from __future__ import print_function
import sys

if sys.version_info[0] >= 3:
  from urllib.request import urlretrieve
else:
  from urllib import urlretrieve

local_filename, headers = urlretrieve('http://jovianlin.com')
html = open(local_filename)

print(html)