}

  @Override
  public boolean equals(@Nullable Object object) {
    if (object == this) {
      return true;
    }
    if (object instanceof ByFunctionOrdering) {
      ByFunctionOrdering<?, ?> that = (ByFunctionOrdering<?, ?>) object;
      return this.function.equals(that.function) && this.ordering.equals(that.ordering);
    }
    return false;
  }

  @Override
  public int hashCode() {