  void visit(PrioritizedChoice &ope) override {
    for (auto op : ope.opes_) {
      op->accept(*this);
      if (is_empty) { return; }
    }
  }
  void visit(PrioritizedChoice &ope) override {
    for (auto op : ope.opes_) {
      op->accept(*this);
      if (is_empty) { return; }
    }
  }