[urlcpp](https://github.com/JosephP91/curlcpp/tree/8b4bbdf4e7deb1581bf6351c03c4fdb5b849a76c)/[test](https://github.com/JosephP91/curlcpp/tree/8b4bbdf4e7deb1581bf6351c03c4fdb5b849a76c/test)/multi.cpp in this example, how can i get all the response of the urls