python - Redirect to previous url in webapp2

Question

I'm trying to make a logout handler to redirect to whatever url called it.

There's a similar question Python webapp2: redirect back

but if I called self.request.url in the LogoutHandler it returns the url used to map to this handler not the page that redirected to that url.

Here's how the structure goes

class LogoutHandler(webapp2.RequestHandler):
     #delete user cookies
     url = self.request.url 
     # this prints (http://www.domain/logout) not (http://www.domain)

class MainHandler(webapp2.RequestHandler):
     #send "/logout" as the href in an anchor tag"for logout" in a template 

application = webapp2.WSGIApplication([
     .....
    ('/', MainHandler),
    ('/logout', LogoutHandler),
     .....
     .....
    ], debug = True)

How can I get 'http://www.domain' or whatever redirected to the logout without adding the previous url as a querystring in the logout url?

webapp2, python 2.7 , Google app engine