@Override
  public @Nullable E floor(E e) {
    return Iterators.<@Nullable E>getNext(headSet(e, true).descendingIterator(), null);
  }

  /**
   * @since 12.0
   */
  @Override
  public @Nullable E ceiling(E e) {
    return Iterables.<@Nullable E>getFirst(tailSet(e, true), null);
  }

  /**
   * @since 12.0
   */
  @GwtIncompatible // NavigableSet
  @Override
  public @Nullable E higher(E e) {

    assertThat(set.ceiling("f")).isNull();
  }

  public void testCeiling_elementPresent() {
    ImmutableSortedSet<String> set =
        ImmutableSortedSet.copyOf(new String[] {"e", "e", "f", "f", "i", "d", "c", "k", "p", "c"});
    assertThat(set.ceiling("f")).isEqualTo("f");
    assertThat(set.ceiling("h")).isEqualTo("i");
    assertThat(set.ceiling("a")).isEqualTo("c");
  }

    assertThat(set.ceiling("f")).isNull();
  }

  public void testCeiling_elementPresent() {
    ImmutableSortedSet<String> set =
        ImmutableSortedSet.copyOf(new String[] {"e", "e", "f", "f", "i", "d", "c", "k", "p", "c"});
    assertThat(set.ceiling("f")).isEqualTo("f");
    assertThat(set.ceiling("h")).isEqualTo("i");
    assertThat(set.ceiling("a")).isEqualTo("c");
  }

      // thus double memory usage.
      this.data =
          new AtomicLongArray(Ints.checkedCast(LongMath.divide(bits, 64, RoundingMode.CEILING)));
      this.bitCount = LongAddables.create();
    }

    // Used by serialization
    LockFreeBitArray(long[] data) {
      checkArgument(data.length > 0, "data length is zero!");

    // The leftmost position at which the greatest of the k lower elements
    // -- the new value of threshold -- might be found.

    int iterations = 0;
    int maxIterations = IntMath.log2(right - left, RoundingMode.CEILING) * 3;
    while (left < right) {
      int pivotIndex = (left + right + 1) >>> 1;

      int pivotNewIndex = partition(left, right, pivotIndex);

      if (pivotNewIndex > k) {

    // The leftmost position at which the greatest of the k lower elements
    // -- the new value of threshold -- might be found.

    int iterations = 0;
    int maxIterations = IntMath.log2(right - left, RoundingMode.CEILING) * 3;
    while (left < right) {
      int pivotIndex = (left + right + 1) >>> 1;

      int pivotNewIndex = partition(left, right, pivotIndex);

      if (pivotNewIndex > k) {

    double fpp = 0.03;
    for (int i = 1; i < 10000; i++) {
      long numBits = BloomFilter.optimalNumOfBits(i, fpp);
      int arraySize = Ints.checkedCast(LongMath.divide(numBits, 64, RoundingMode.CEILING));
      assertEquals(
          arraySize * Long.SIZE, BloomFilter.create(unencodedCharsFunnel(), i, fpp).bitSize());
    }
  }

  /**

    }
  }

  /** A bit mask were all bits are set. */
  private static final int ALL_SET = ~0;

  private static int ceilToPowerOfTwo(int x) {
    return 1 << IntMath.log2(x, RoundingMode.CEILING);
  }

  /*
   * This method was written by Doug Lea with assistance from members of JCP JSR-166 Expert Group
   * and released to the public domain, as explained at

    return max(
        ImmutableCollection.Builder.DEFAULT_INITIAL_CAPACITY,
        sqrt(inputElementsIncludingAnyDuplicates, RoundingMode.CEILING));
  }

  @GwtIncompatible @J2ktIncompatible   private static final long serialVersionUID = 0xcafebabe;

      int end = min(start + size, list.size());
      return list.subList(start, end);
    }

    @Override
    public int size() {
      return IntMath.divide(list.size(), size, RoundingMode.CEILING);
    }

    @Override
    public boolean isEmpty() {
      return list.isEmpty();
    }
  }

  private static final class RandomAccessPartition<T extends @Nullable Object> extends Partition<T>