I think C++'s (std::chrono::time_point, std::chrono::time_delta) together make a torsor. The group G is std::chrono::time_delta and the set is std::chrono::time_point. Both the group action (time_point + time_delta) and the group operation (time_delta + time_delta) are declared here https://en.cppreference.com/w/cpp/chrono/time_point/operator....