func top(result *[]*competition_detail.BrandWord, topN int) {
    sort.SliceStable(*result, func(i, j int) bool {
        return (*result)[i].ProductFrequency > (*result)[j].ProductFrequency
    })
    if len(*result) > topN {
        *result = (*result)[0:topN]
    }
}


type BrandWord struct {
    ProductPropertyValue string `thrift:"product_property_value,1" json:"product_property_value"`
    ProductFrequency     int64  `thrift:"product_frequency,2" json:"product_frequency"`
}