return false;
  }

  @Override
  public C first() {
    // requireNonNull is safe because we checked the range is not empty in ContiguousSet.create.
    return requireNonNull(range.lowerBound.leastValueAbove(domain));
  }

  @Override
  public C last() {
    // requireNonNull is safe because we checked the range is not empty in ContiguousSet.create.

    return false;
  }

  @Override
  public C first() {
    // requireNonNull is safe because we checked the range is not empty in ContiguousSet.create.
    return requireNonNull(range.lowerBound.leastValueAbove(domain));
  }

  @Override
  public C last() {
    // requireNonNull is safe because we checked the range is not empty in ContiguousSet.create.