How to use the alephclient.services.geoextract_pb2.CountryTags function in alephclient

for index, country in self.automaton.iter(text):
                # log.debug("Matched: %s -> %s", name, country)
                country_tags.append(country)

        doc_tags = []
        co_counts = Counter(country_tags)
        top_n = co_counts.most_common(self.MAX_TAGS)

        for tag_num in range(1, self.MAX_TAGS + 1):
            if len(top_n) >= tag_num:
                freq = top_n[tag_num-1][1] / max(1, word_count)
                log.info('tag is %s, freq = %.2f', top_n[tag_num-1], freq)
                if freq >= self.TAG_FREQUENCY_CUT:
                    doc_tags.append(top_n[tag_num-1][0])

        return CountryTags(countries=doc_tags)