Method operator-

src/include/minja/minja.hpp:458–463

  }

  Value operator-() const {
      if (is_number_integer())
        return -get<int64_t>();
      else
        return -get<double>();
  }
  std::string to_str() const {
    if (is_string()) return get<std::string>();
    if (is_number_integer()) return std::to_string(get<int64_t>());