Not really a problem, but it's good practice to name strng str

Nice kata, good if you want to learn about closures

The kata says only to ignore puncuation marks. But when you submit, some random tests (atleast in my case) have double spaces in them (' ') which the kata expects should also be returned as is. This should atleast be mentioned once in the details!

I am suprised nobody used a set to solve the problem. All the top one liner solutions have a complexity of O(m * n), which is inefficent for large inputs