Мне кажется ответ неверный.

Question

Отсутствует global внутри функции

Answer 1

Make your question more descriptive, it's incomplete. Tag the language too, because your question might be specific to the language you're using. Here are the guidelines about how to use this forum efficiently. Do have a look at it. All the best =)

https://www.sololearn.com/discuss/1316935/?ref=app