Question2 { public static int countBandMembersInternal(List<Artist> artists) { return artists.stream() .map(artist -> artist.getMembers().count()) .reduce(0L, Long::sum) .intValue(); }  static int countBandMembersInternal(List<Artist> artists);  }
@Test public void internal() { assertEquals(4, countBandMembersInternal(Arrays.asList(SampleData.johnColtrane, SampleData.theBeatles))); }