Python/AppEngine: Get client browser information

How can I get client browser information (type, version, etc.) using Python/AppEn开发者_StackOverflow中文版gine?

---

From the User-Agent header:

user_agent_string = self.request.headers['user-agent']

http://code.google.com/appengine/docs/python/tools/webapp/requestclass.html#Request_headers