title: How do I add a header to urllib2 opener?
body: <pre><code>cj = cookielib.CookieJar()
  opener = urllib2.build_opener(urllib2.HTTPCookieProcessor(cj))    
  opener.open('http://abc.com')
  opener.open('http://google.com')
  </code></pre>
  
  <p>As you can see, I use opener to visit different websites, using a cookie jar. Can I set a header so that each time a website is it, the header is applied?</p>