CountryBusiness.kt

interface ArticleConsumer {
    fun use(article: ItaArticle)
    fun use(article: DeuArticle)
    fun use(article: ArticleNotFound)
}

fun useAnArticle(article: Article) : String {
    var x = ""

    article.applyTo(object : ArticleConsumer {
        
        override fun use(article: ItaArticle) {
            x = article.itaData1
        }

        override fun use(article: DeuArticle) {
            x = article.deuData1
        }

        override fun use(article: ArticleNotFound) {
            x = "not found"
        }

    })

    return x
}