[tianshuo]

I reported multiple bugs in Codewars for Javascript, and created one of the hardest katas with anti-cheat here(https://www.codewars.com/kata/mystery-function-number-2). The founder remarks that Codewars has sanity checks if you are meddling with the test system and will punish you if you abuse it too much. Testing out one or two cheats is okay, using it for too much katas will get you banned.