Hi iphark. For this particular kata, research "lookahead assertion", "character set", and how the ^ (carat) and $ (dollar sign) work in regex. Hopefully this helped!

I'm new to regex, but it seems that you don't allow for a reoccurrence of any letters or numbers.

For example:
"(?=.[a-z])" returns the first instance of any lowercase letter, but does not allow for duplicates.

"(?=.*[a-z])" returns the first instance of any lowercase letter, but the asterisk symbol allows for 0 to infinite repititions.

When I modified my code that passed all tests to remove the asterisk symbol so it look like yours, my test failed. Also, you should (from what I've read) place the "{6,}" after the "(?=.\d)" and add a "$" at the end to tell regex that the string is done (good habits to reduce errors when dealing with multiline comments if you ever do). Hopefully this helped!

Received output "It should work for random inputs too: ['a', 5, -5, -2, 'x', -3, 'pippi', 0, 0] should equal ['a', 5, '0', -5, -2, 'x', -3, 'pippi', 0]".
The answer from the kata does not move all 0's to the back.