docs: def authenticate_redirect(self, callback_uri=None,
                                ask_for=["name", "email", "language", "username"]):
          """
          Performs a redirect to the authentication URL for this service.
  
          After authentication, the service will redirect back to the given
          callback URI.
  
          We request the given attributes for the authenticated user by
          default (name, email, language, and username). If you don't need
          all those attributes for your app, you can request fewer with
          the |ask_for| keyword argument.
          """
          callback_uri = callback_uri or request.url
          args = self._openid_args(callback_uri, ax_attrs=ask_for)
          return redirect(self._OPENID_ENDPOINT +
                          ("&" if "?" in self._OPENID_ENDPOINT else "?") +
                          urllib.urlencode(args))