Don't use the functions from the map object, but keep a separate function reference for validation? I mean if you want to cheat you always can. But that's not

Don't use the functions from the map object, but keep a separate function reference for validation? I mean if you want to cheat you always can. But that's not the point. Right now you can cheat using official apis. Just use map._blah() for internal use By the way: Same trick works for keys.