assertThat(set.tailSet("a")).containsExactly("b", "c", "d", "e", "f").inOrder();
    assertSame(this.<String>of(), set.tailSet("g"));
  }

  public void testOf_subSet() {
    SortedSet<String> set = of("e", "f", "b", "d", "c");
    assertTrue(set.subSet("c", "e") instanceof ImmutableSortedSet);
    assertThat(set.subSet("c", "e")).containsExactly("c", "d").inOrder();