There are two tests that give me a float value when decrypting, even though all inputs should be valid. All tests pass except two and they both are resulting in a float when doing the reverse math of encrypting. What could be my issue here?

Couldn't you use a lambda function instead of defining a new function? Or is there a purpose to making the new function for the key?

Forgive my n00biness while I ask: does this optimize anything by defining the classes, or is this a flex and/or for your own class practice? You're way ahead of me, so it's clear you have a deeper understanding than I do, even if this is a joke lol.

I was down the same path as you for a bit. Doing these for an hour or two every day, but this one held me up the last two days before something clicked last night. This solution is a cleaner version of what ended up being mine. Definitely faster, as well.