from google.appengine.api import users


# Get currently logged in user if available.
user = users.get_current_user()


# Redirecting to sign-in page.
redirect_location = users.create_login_url(self.request.uri)

from webob.exc import HTTPTemporaryRedirect
redirect_response = HTTPTemporaryRedirect(location=url)
return redirect_response(environ, start_response)