Logout URL for Google App Engine

gistfile1.py

class LogoutPage(webapp2.RequestHandler):
    def get(self):
        target_url = self.request.referer or '/'
        if os.environ.get('SERVER_SOFTWARE', '').startswith('Development/'):
            self.redirect(users.create_logout_url(target_url))
            return

        # On the production instance, we just remove the session cookie, because
        # redirecting users.create_logout_url(...) would log out of all Google
        # (e.g. Gmail, Google Calendar).
        #
        # It seems that AppEngine is setting the ACSID cookie for http:// ,
        # and the SACSID cookie for https:// . We just unset both below.
        cookie = Cookie.SimpleCookie()
        cookie['ACSID'] = ''
        cookie['ACSID']['expires'] = -86400  # In the past, a day ago.
        self.response.headers.add_header(*cookie.output().split(': ', 1))
        cookie = Cookie.SimpleCookie()
        cookie['SACSID'] = ''
        cookie['SACSID']['expires'] = -86400
        self.response.headers.add_header(*cookie.output().split(': ', 1))
        self.redirect(target_url)

app = webapp2.WSGIApplication(  [
                                    (r'/logout', LogoutPage ),
                                ],
                              debug=True)