def save(self, doc):
        if doc.id:
            return self.update(doc)
        else:
            return self.insert(doc)
def _rematcher(regex):
    """compile the regexp with the best available regexp engine and return a
    matcher function"""
    m = util.re.compile(regex)
    try:
        # slightly faster, provided by facebook's re2 bindings
        return m.test_match
    except AttributeError:
        return m.match