Practically, it's all through this `type_traits` header that (often) end up in unreadable messes. It's all possible because of the catchy acronym SFINAE. It doesn't make much sense to me either, so I avoid it :)

https://en.cppreference.com/w/cpp/language/sfinae

You don't really need to use sfinae anymore, concepts are cleaner and easier to follow, also this library appears to use concepts