@Override
  public SortedMap<K, V> headMap(K toKey) {
    return headMap(toKey, false);
  }

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

  @Override
  public @Nullable Entry<K, V> higherEntry(K key) {
    return delegate.higherEntry(checkValid(key));
  }

  @Override

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

    return derivedSuites;
  }

  @Override
  protected SetTestSuiteBuilder<K> createDerivedKeySetSuite(TestSetGenerator<K> keySetGenerator) {

    @Override
    public NavigableSet<V> headSet(@ParametricNullness V toElement, boolean inclusive) {
      return wrap(getSortedSetDelegate().headSet(toElement, inclusive));
    }

    @Override
    public NavigableSet<V> tailSet(@ParametricNullness V fromElement, boolean inclusive) {
      return wrap(getSortedSetDelegate().tailSet(fromElement, inclusive));
    }
  }

    ImmutableSortedSet<C> subSet(Range<C> range) {
      return subRangeSet(range).asSet(domain);
    }

    @Override
    ImmutableSortedSet<C> headSetImpl(C toElement, boolean inclusive) {
      return subSet(Range.upTo(toElement, BoundType.forBoolean(inclusive)));
    }

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

    } else {
      int k = 20;
      return BigInteger.valueOf(LongMath.factorial(k)).multiply(oldSlowFactorial(k, n));
    }
  }

  /** Returns the product of {@code n1} exclusive through {@code n2} inclusive. */
  @SuppressWarnings("UseCorrectAssertInTests") // TODO(b/345814817): Remove or convert assertion.
  private static BigInteger oldSlowFactorial(int n1, int n2) {
    assert n1 <= n2;

  static int flip(int value) {
    return value ^ Integer.MIN_VALUE;
  }

  /**
   * Compares the two specified {@code int} values, treating them as unsigned values between {@code
   * 0} and {@code 2^32 - 1} inclusive.
   *
   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated; use the
   * equivalent {@link Integer#compareUnsigned(int, int)} method instead.
   *

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

    return derivedSuites;
  }

  /**
   * Creates a suite whose set has some elements filtered out of view.
   *

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

    return derivedSuites;
  }

  /**
   * Creates a suite whose set has some elements filtered out of view.
   *

        // Of course, we have to use binary search to find the precise
        // breakpoint...
        int lower = foundIndex;
        int upper = list.size() - 1;
        // Everything between lower and upper inclusive compares at >= 0.
        while (lower < upper) {
          int middle = (lower + upper + 1) >>> 1;
          int c = comparator.compare(list.get(middle), key);
          if (c > 0) {
            upper = middle - 1;

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

    return derivedSuites;
  }

  @Override
  protected SetTestSuiteBuilder<K> createDerivedKeySetSuite(TestSetGenerator<K> keySetGenerator) {