}

  /**
   * Returns {@code true} if the provided keys are among the keys provided when the table was
   * constructed.
   */
  @Override
  public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
    return containsRow(rowKey) && containsColumn(columnKey);
  }

  /**
   * Returns {@code true} if the provided column key is among the column keys provided when the
   * table was constructed.

  }

  /**
   * Returns {@code true} if the provided keys are among the keys provided when the table was
   * constructed.
   */
  @Override
  public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
    return containsRow(rowKey) && containsColumn(columnKey);
  }

  /**
   * Returns {@code true} if the provided column key is among the column keys provided when the
   * table was constructed.