changed difficulty parsing in problem()

[hugo-morvan]

changed the difficulty parsing in the problem() function to match how it is done in problems() as the problem() function throws a ValueError when the problem has a range of difficulty.

[RussellDash332]

Thanks for the catch!

[hugo-morvan]

Hey, I believe my fix for the problem was wrong because API response is structured/handled differently between problem() and problems(). I think difficulty = float((re.findall('[\d\.]+', div_text[0]) or [None])[-1]) if div_text else None would do the trick, but you might want to double check.
Sorry for the inconvenience.