for the given elem, return the @match function that will be applied

def get_match(self, elem):
        """for the given elem, return the @match function that will be applied"""
        for m in self.matches:
            if (m.expression is not None and eval(m.expression)==True) \
            or (m.xpath is not None and len(elem.xpath(m.xpath, namespaces=m.namespaces)) > 0):
                LOG.debug("=> match: %r" % m.expression)
                return m