prevent visually similar characters from appearing in the same generated url
The point of a short link is that it's easy to share, but this benefit is limited if no one can read your link. If the link is go.gmu.edu/1Ol0, for some fonts and most people's handwriting, it's easy to get confused.
I'm labelling this issue at the medium difficulty because I'm not sure if an ideal implementation is elegant or self-evident.
(I think, from a quick look) this functionality would be added to the
generate_valid_short() method in the URL model at