Functions { public static <T> Function<Object, T> constant(T output) { return input -> output; } private  Functions(); static Function<List<T>, T> firstOfList(); static Function<List<T>, T> lastOfList(); static Function<List<T>, T> nthOfList(int index); static Function<List<T>, List<T>> permutationOfList(
      int... indexes); static Function<List<T>, List<T>> withoutSeparators(); static Function<Object, T> constant(T output);  }
@Test public void testConstant() { assertEquals((Object) 'a', constant('a').apply('b')); assertEquals((Object) 'b', constant('b').apply('c')); }