private static <T, X> Collector<T, ?, X> mode0(Function<? super Seq<Tuple2<T, Long>>, ? extends X> transformer) {
        return Collector.of(
            () -> new LinkedHashMap<T, Long>(),
            (m, v) -> m.compute(v, (k1, v1) -> v1 == null ? 1L : v1 + 1L),
            (m1, m2) -> {
                m1.putAll(m2);
                return m1;
            },
            m -> Seq.seq(m).transform(transformer)
        );
    }
Get a {@link Collector} that calculates the <code>MODE()</code> function.
jOOL-java-8/src/main/java/org/jooq/lambda/Agg.java