In code examples I see wrong indentation, usage for non-pythonic ways to get data from lists, ";"character here and there, usage of parenthesis (“if(visited[temp.data] == False)”) etc. etc.
They are all over the course. Just take a look at Solution Review: Implement Breadth First Search. But there are plenty of similar issues. I even saw check of “self is None” in tree algorithms which is non-sense. Somebody who doesn’t know Python tried to adapt it from another language and failed at that task.