@Test
public void works_with_multiple_types() {
final Stream<Integer> stream = Streams.of(6, 3, 2, 7);
assertThat(stream.foldLeft(joinAsString(), ""), is(", 6, 3, 2, 7"));
}
@Test
public void works_with_a_single_type() {
final Stream<Integer> stream = Streams.of(6, 3, 2, 7);
assertThat(stream.foldLeft(summation(), 0), is(18));
}