def _fail_route(self):
        """Fail the current tokenization route.

        Discards the current stack/context/textbuffer and raises
        :exc:`.BadRoute`.
        """
        context = self._context
        self._memoize_bad_route()
        self._pop()
        raise BadRoute(context)
Fail the current tokenization route.

        Discards the current stack/context/textbuffer and raises
        :exc:`.BadRoute`.