I once worked with a true 10x programmer. The guy used C++ metaprogramming to avoid boiler-plate code. Any by "used" I mean he needed the best preprocessors and compilers at the time to just write his code. He once single-handedly porting our >1m LOC codebase to Java over a weekend (admittedly, a 3-day weekend, but still).
When new people asked him if he knew C++ his standard answer was "I know enough to know I don't know C++".
When new people asked him if he knew C++ his standard answer was "I know enough to know I don't know C++".