Try to match the TextLayer with choice's intents.

async def _rank_text(self, choices):
        """
        Try to match the TextLayer with choice's intents.
        """

        tl = self.request.get_layer(l.RawText)
        best = 0.0

        for slug, params in choices.items():
            strings = []

            if params['intent']:
                intent = getattr(intents, params['intent'])
                strings += await intent.strings(self.request)

            if params['text']:
                strings.append((params['text'],))

            matcher = Matcher([tuple(Trigram(y) for y in x) for x in strings])
            score = matcher % Trigram(await render(tl.text, self.request))

            if score > best:
                self.chosen = params
                self.slug = slug
                best = score

        if self.when is None or self.slug == self.when:
            return best