assertEquals(ImmutableSortedSet.of(4, 6, 8, 10), Sets.subSet(set, Range.atLeast(4)));
    assertEquals(ImmutableSortedSet.of(8, 10), Sets.subSet(set, Range.atLeast(7)));
    assertEquals(empty, Sets.subSet(set, Range.atLeast(20)));

    assertEquals(set, Sets.subSet(set, Range.greaterThan(0)));
    assertEquals(ImmutableSortedSet.of(6, 8, 10), Sets.subSet(set, Range.greaterThan(4)));

    SortedSet<String> set = of("e");
    assertTrue(set.subSet("c", "g") instanceof ImmutableSortedSet);
    assertThat(set.subSet("c", "g")).contains("e");
    assertThat(set.subSet("e", "g")).contains("e");
    assertSame(this.<String>of(), set.subSet("f", "g"));
    assertSame(this.<String>of(), set.subSet("c", "e"));
    assertSame(this.<String>of(), set.subSet("c", "d"));
  }

  public void testSingle_first() {

      } else if (from == Bound.EXCLUSIVE && to == Bound.EXCLUSIVE) {
        return set.subSet(firstExclusive, false, lastExclusive, false);
      } else if (from == Bound.EXCLUSIVE && to == Bound.INCLUSIVE) {
        return set.subSet(firstExclusive, false, lastInclusive, true);
      } else if (from == Bound.INCLUSIVE && to == Bound.INCLUSIVE) {
        return set.subSet(firstInclusive, true, lastInclusive, true);
      } else {

      } else if (from == Bound.EXCLUSIVE && to == Bound.EXCLUSIVE) {
        return set.subSet(firstExclusive, false, lastExclusive, false);
      } else if (from == Bound.EXCLUSIVE && to == Bound.INCLUSIVE) {
        return set.subSet(firstExclusive, false, lastInclusive, true);
      } else if (from == Bound.INCLUSIVE && to == Bound.INCLUSIVE) {
        return set.subSet(firstInclusive, true, lastInclusive, true);
      } else {

         * greater than tooHigh.
         */
        return ContiguousSet.create(Range.openClosed(0, 1), DiscreteDomain.integers()).subSet(0, 1);
      }
      int tooHigh = set.last() + 1;
      int tooLow = set.first() - 1;
      set.add(tooHigh);
      set.add(tooLow);
      return checkedCreate(set).subSet(tooLow + 1, tooHigh);
    }
  }

  @GwtIncompatible // NavigableSet

  }

  /**
   * {@inheritDoc}
   *
   * <p>This method returns a serializable {@code ImmutableSortedSet}.
   *
   * <p>The {@link SortedSet#subSet} documentation states that a subset of a subset throws an {@link
   * IllegalArgumentException} if passed a {@code fromElement} smaller than an earlier {@code
   * fromElement}. However, this method doesn't throw an exception in that situation, but instead

    if (features.remove(CollectionFeature.ALLOWS_NULL_VALUES)) {
      // the null value might be out of bounds, so we can't always construct a subset with nulls
      features.add(CollectionFeature.ALLOWS_NULL_QUERIES);
      // but add null might still be supported if it happens to be within range of the subset
      suppressing.add(CollectionAddTester.getAddNullUnsupportedMethod());

    if (features.remove(CollectionFeature.ALLOWS_NULL_VALUES)) {
      // the null value might be out of bounds, so we can't always construct a subset with nulls
      features.add(CollectionFeature.ALLOWS_NULL_QUERIES);
      // but add null might still be supported if it happens to be within range of the subset
      suppressing.add(CollectionAddTester.getAddNullUnsupportedMethod());

    @Override
    public SortedSet<E> create(Object... elements) {
      List<?> normalValues = (List<?>) asList(elements);
      List<E> extremeValues = new ArrayList<>();

      // nulls are usually out of bounds for a subset, so ban them altogether
      for (Object o : elements) {
        if (o == null) {
          throw new NullPointerException();
        }
      }

      // prepare extreme values to be filtered out of view

         * greater than tooHigh.
         */
        return ContiguousSet.create(Range.openClosed(0, 1), DiscreteDomain.integers()).subSet(0, 1);
      }
      int tooHigh = set.last() + 1;
      int tooLow = set.first() - 1;
      set.add(tooHigh);
      set.add(tooLow);
      return checkedCreate(set).subSet(tooLow + 1, tooHigh);
    }
  }

  @GwtIncompatible // NavigableSet