epequeno/ThinkPy-Solutions — comment on commit 000a554a5f65ef42977045c0c9edffd38988b996
File:  line 0
By epequeno:

I kind of half-assed this one the first time through. ord() and chr() also work to map capital letters and other various symbols which muck this up a bit. I had to go back and work the kinks out because a problem in a later chapter requires a correct, working version of this program.

This handles cases where the amount to rotate way out of the range of lower case letters (97 to 122) in either direction and brings them back into that range. It also converts all letters to lowercase. I should probably also include an str.isalpha() test to filter out punctuation marks and other such things but that'll be later.