text: #include <iostream>
  #include <future>
  
  void fun()
  {
      std::cerr << "    hello from fun\n";
  }
  
  std::future<void> asyncCall(char const *label)
  {
      std::cerr << label << " async call starts\n";
      auto ret = std::async(fun);
      std::cerr << label << " async call ends\n";
      return ret;
  }
  
  //code
  int main()
  {
      auto ret1 = asyncCall("First");
      auto ret2 = asyncCall("Second");
  
      ret1.get();
      ret2.get();
  }
  //=
  