Why can't you reverse a string with a flag emoji?
So, in terms of acing interviews, increasingly one of the best answers to the question "Write some code that reverses a string" is that in a world of unicode, "reversing a string" is no longer possible or meaningful.You'll probably be told "oh, assume US ASCII" or something, but in the meantime, if you can back that up when they dig into it, you'll look really smart.