}

 private:
  Predicate* MakeNotPredicateImpl(Predicate* pred) {
    IncrementStackDepth stack_frame(this);
    if (!stack_frame.HasOverflowed()) {
      if (Predicate* simplified = SimplifyUsingDeMorgan(pred)) {
        return simplified;
      }

      // ~~A => A
      if (auto* not_pred = dynamic_cast<NotPredicate*>(pred)) {
        return not_pred->operand();
      }
    }