text: namespace otera {
      class RandomGenerator {
          public:
              RandomGenerator() : mt64(std::chrono::steady_clock::now().time_since_epoch().count()) {}
  
              // [a, b)
              long long operator()(long long a, long long b) {
                  std::uniform_int_distribution<long long> dist(a, b - 1);
                  return dist(mt64);
              }
          private:
              std::mt19937_64 mt64;
      };
  } // namespace otera
  