def _prepare_text(self, text):
        """Returns `text` with each consituent token wrapped in HTML markup
        for later match annotation.

        :param text: text to be marked up
        :type text: `str`
        :rtype: `str`

        """
        # Remove characters that should be escaped for XML input (but
        # which cause problems when escaped, since they become
        # tokens).
        text = re.sub(r'[<>&]', '', text)
        pattern = r'({})'.format(self._tokenizer.pattern)
        return re.sub(pattern, self._base_token_markup, text)