How to use the tatsu.util.re.compile function in TatSu

def regex(self, ast, *args):
        pattern = ast
        try:
            re.compile(pattern)
        except (TypeError, re.error) as e:
            raise FailedSemantics('regexp error: ' + str(e))
        return pattern

ctx = context or ModelContext(
            self.rules,
            trace=trace,
            keywords=self.keywords,
            **kwargs)

        semantics = notnone(semantics, self.semantics)
        left_recursion = notnone(left_recursion, self.left_recursion)
        parseinfo = notnone(parseinfo, self._use_parseinfo)
        comments_re = notnone(comments_re, self.comments_re)
        eol_comments_re = notnone(eol_comments_re, self.eol_comments_re)
        nameguard = notnone(nameguard, self.nameguard)
        namechars = notnone(namechars, self.namechars)
        whitespace = notnone(whitespace, self.whitespace)
        if whitespace:
            whitespace = re.compile(whitespace)

        return ctx.parse(
            text,
            rule_name=start,
            filename=filename,
            semantics=semantics,
            trace=trace,
            whitespace=whitespace,
            comments_re=comments_re,
            eol_comments_re=eol_comments_re,
            left_recursion=left_recursion,
            parseinfo=parseinfo,
            nameguard=nameguard,
            namechars=namechars,
            **kwargs
        )

def __init__(
        self,
        text,
        whitespace=re.compile(" "),
        nameguard=None,
        comments_re=None,
        eol_comments_re=None,
        ignorecase=None,
        namechars="",
        **kwargs,
    ):
        super(UnknownBuffer, self).__init__(
            text,
            whitespace=whitespace,
            nameguard=nameguard,
            comments_re=comments_re,
            eol_comments_re=eol_comments_re,
            ignorecase=ignorecase,
            namechars=namechars,
            **kwargs,

def __init__(
        self,
        whitespace=re.compile(" "),
        nameguard=None,
        comments_re=None,
        eol_comments_re=None,
        ignorecase=None,
        left_recursion=True,
        parseinfo=True,
        keywords=None,
        namechars="",
        buffer_class=UnknownBuffer,
        **kwargs,
    ):
        if keywords is None:
            keywords = KEYWORDS
        super(UnknownParser, self).__init__(
            whitespace=whitespace,
            nameguard=nameguard,