I have a similar solution. I created two tuples of alphabet. The string.ascii is a big help. Thanks.

Hi mate, thanks for taking the time to give me some advice - I really appreciate it!

By the way, to save yourself from needing to write the whole alphabet out twice, you can just do the following (144 characters less than your solution)

import string
alphabet_lower = list(string.ascii_lowercase)
alphabet_upper = list(string.ascii_uppercase)