@Test
public void testAggMultiple_Named() {

    DataFrame aggregated = Series.forData("a", "b", "cd", "e", "fg")
            .group((String s) -> s.length())
            .aggMultiple(
                    SeriesAggregator.first().named("f"),
                    SeriesAggregator.concat("|").named("c1"),
                    SeriesAggregator.concat("_").named("c2"));
    new DataFrameAsserts(aggregated, "f", "c1", "c2")
            .expectHeight(2)
            .expectRow(0, "a", "a|b|e", "a_b_e")
            .expectRow(1, "cd", "cd|fg", "cd_fg");
}