My current least-favorite parts of the google style guide are 'don't overload operator< and std::hash, but keep them as free functions and use the other ctors f

My current least-favorite parts of the google style guide are 'don't overload operator< and std::hash, but keep them as free functions and use the other ctors for set/unordered_set/etc', because I'm thinking if you're going to have to write those things anyway, you might as well do it in a way to make the api easier.