I notice that a lot of solutions, including the editorial, use isalnum(). If it works with this problem, I guess that's great, but I think a lot of people forget that function matches a lot of non-ASCII characters.

Python's isalnum() method works with Unicode characters. It returns True if all characters in the string are alphanumeric, meaning they are either letters or numbers according to the Unicode standard. This includes characters from various languages and scripts beyond just the basic Latin alphabet and Arabic numerals.

For example, isalnum() would return True for strings containing characters like '½' (vulgar fraction one half), '౩' (Telugu digit three), superscript digits, or subscript digits as these are recognized as alphanumeric within the Unicode character set.