}

  @Override
  public boolean contains(@Nullable Object rowKey, @Nullable Object columnKey) {
    Map<C, V> row = safeGet(rowMap(), rowKey);
    return row != null && Maps.safeContainsKey(row, columnKey);
  }

  @Override
  public @Nullable V get(@Nullable Object rowKey, @Nullable Object columnKey) {
    Map<C, V> row = safeGet(rowMap(), rowKey);
    return (row == null) ? null : safeGet(row, columnKey);
  }

  }

  @Override
  public boolean contains(@Nullable Object rowKey, @Nullable Object columnKey) {
    Map<C, V> row = safeGet(rowMap(), rowKey);
    return row != null && Maps.safeContainsKey(row, columnKey);
  }

  @Override
  public @Nullable V get(@Nullable Object rowKey, @Nullable Object columnKey) {
    Map<C, V> row = safeGet(rowMap(), rowKey);
    return (row == null) ? null : safeGet(row, columnKey);
  }

   *
   * @throws IllegalArgumentException if {@code rowKey} is not in {@link #rowKeySet()} or {@code
   *     columnKey} is not in {@link #columnKeySet()}.
   */
  @CanIgnoreReturnValue
  @Override
  public @Nullable V put(R rowKey, C columnKey, @Nullable V value) {
    checkNotNull(rowKey);
    checkNotNull(columnKey);
    Integer rowIndex = rowKeyToIndex.get(rowKey);

        Spliterator.DISTINCT | Spliterator.SIZED,
        size());
  }

  @Override
  public Map<C, V> row(R rowKey) {
    return new Row(rowKey);
  }

  class Row extends IteratorBasedAbstractMap<C, V> {
    final R rowKey;

    Row(R rowKey) {
      this.rowKey = checkNotNull(rowKey);
    }

    @Nullable Map<C, V> backingRowMap;

    final void updateBackingRowMapField() {

   * by applying the given {@code AsyncFunction} to the result of the original {@code Future}.
   * Example usage:
   *
   * {@snippet :
   * FluentFuture<RowKey> rowKeyFuture = FluentFuture.from(indexService.lookUp(query));
   * ListenableFuture<QueryResult> queryFuture =
   *     rowKeyFuture.transformAsync(dataService::readFuture, executor);
   * }
   *

   * by applying the given {@code AsyncFunction} to the result of the original {@code Future}.
   * Example usage:
   *
   * {@snippet :
   * ListenableFuture<RowKey> rowKeyFuture = indexService.lookUp(query);
   * ListenableFuture<QueryResult> queryFuture =
   *     transformAsync(rowKeyFuture, dataService::readFuture, executor);
   * }
   *