For urllib
you can use:
from urllib import FancyURLopener
class MyOpener(FancyURLopener, object):
version = 'Mozilla/5.0 (Windows; U; Windows NT 5.1; it; rv:1.8.1.11) Gecko/20071127 Firefox/2.0.0.11'
myopener = MyOpener()
myopener.retrieve('https://www.google.com/search?q=test', 'useragent.html')