Map tuple

import io.reactivex.Observable;
import javaslang.Tuple;

public class TupleMap {

    public static void main(String[] args) {
        Observable.just("1","a", "2", "b", "3", "c")
        .buffer(2)
        .map(list -> Tuple.of(list.get(0), list.get(1)))
        .doOnNext(System.out::println)
        .map(tuple -> tuple.map(
                number -> number + "_num",
                letter -> letter + "_letter"
        ))
        .forEach(System.out::println);
    }

}