for (List<Integer> contents : SAMPLE_INPUTS) {
        for (int i = 0; i < 10; i++) {
          for (boolean inclusive : ImmutableList.of(true, false)) {
            assertEquals(
                filter(createUnfiltered(contents).headSet(i, inclusive), EVEN),
                filter(createUnfiltered(contents), EVEN).headSet(i, inclusive));
          }
        }
      }
    }

    public void testNavigableTailSet() {

  }

  @Override
  public UnmodifiableIterator<E> iterator() {
    return forward.descendingIterator();
  }

  @Override
  ImmutableSortedSet<E> headSetImpl(E toElement, boolean inclusive) {
    return forward.tailSet(toElement, inclusive).descendingSet();
  }

  @Override
  ImmutableSortedSet<E> subSetImpl(
      E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {

		between the lower and upper bound specified by the Range Query. Range
		Queries can be inclusive or exclusive of the upper and lower bounds.
		If you want to find documents whose content_length fields have values
		between 1000 and 10000, inclusive, you can enter:
		<pre>content_length:[1000 TO 10000]</pre>
		If you want to exclude the upper and lower bounds, use "{}".
	</dd>
	<dt>Boost</dt>

  OPEN(false),
  CLOSED(true);

  final boolean inclusive;

  BoundType(boolean inclusive) {
    this.inclusive = inclusive;
  }

  /** Returns the bound type corresponding to a boolean value for inclusivity. */
  static BoundType forBoolean(boolean inclusive) {
    return inclusive ? CLOSED : OPEN;
  }

      derivedSuites.add(createSubsetSuite(parentBuilder, Bound.EXCLUSIVE, Bound.NO_BOUND));
      derivedSuites.add(createSubsetSuite(parentBuilder, Bound.EXCLUSIVE, Bound.EXCLUSIVE));
      derivedSuites.add(createSubsetSuite(parentBuilder, Bound.EXCLUSIVE, Bound.INCLUSIVE));
      derivedSuites.add(createSubsetSuite(parentBuilder, Bound.INCLUSIVE, Bound.INCLUSIVE));
    }

      derivedSuites.add(createSubmapSuite(parentBuilder, Bound.EXCLUSIVE, Bound.NO_BOUND));
      derivedSuites.add(createSubmapSuite(parentBuilder, Bound.EXCLUSIVE, Bound.EXCLUSIVE));
      derivedSuites.add(createSubmapSuite(parentBuilder, Bound.EXCLUSIVE, Bound.INCLUSIVE));
      derivedSuites.add(createSubmapSuite(parentBuilder, Bound.INCLUSIVE, Bound.INCLUSIVE));
    }

    return derivedSuites;

  @Override
  public SortedSet<E> headSet(E toElement) {
    return headSet(toElement, false);
  }

  @Override
  public NavigableSet<E> headSet(E toElement, boolean inclusive) {
    return new SafeTreeSet<>(delegate.headSet(checkValid(toElement), inclusive));
  }

  @Override
  public @Nullable E higher(E e) {
    return delegate.higher(checkValid(e));
  }

  @Override
  public boolean isEmpty() {

  }

  @Override
  public NavigableMap<K, V> headMap(@ParametricNullness K toKey, boolean inclusive) {
    return delegate().headMap(toKey, inclusive);
  }

  @Override
  public NavigableMap<K, V> tailMap(@ParametricNullness K fromKey, boolean inclusive) {
    return delegate().tailMap(fromKey, inclusive);
  }

  /**
   * A sensible definition of {@link #headMap(Object)} in terms of {@link #headMap(Object,

  }

  @Override
  public NavigableMap<K, V> headMap(@ParametricNullness K toKey, boolean inclusive) {
    return delegate().headMap(toKey, inclusive);
  }

  @Override
  public NavigableMap<K, V> tailMap(@ParametricNullness K fromKey, boolean inclusive) {
    return delegate().tailMap(fromKey, inclusive);
  }

  /**
   * A sensible definition of {@link #headMap(Object)} in terms of {@link #headMap(Object,

      for (boolean inclusive : new boolean[] {false, true}) {
        assertThat(navigableMap.headMap(key, inclusive).entrySet())
            .containsExactlyElementsIn(expected.headMap(key, inclusive).entrySet())
            .inOrder();
        assertThat(navigableMap.tailMap(key, inclusive).entrySet())
            .containsExactlyElementsIn(expected.tailMap(key, inclusive).entrySet())
            .inOrder();