What is being repeated that shouldn't be in this solution?

+1 to the pool of "Please implement solution downvotes" suggestions. So tired of seeing terrible solutions snowball to accumulate insane number of "best practice" votes simply because they are cryptically short.

Swallowing any helpful error messages simply to return string "Error" does not seem like best practices to me.

All-around bad Python translation -- super lazy

For anyone seeing this years later in a similar boat as CodingRookie, res is likely (but not necessarily) short for result.

res could have been any word at all, but the author of the kata decided on res.

The ordering of the vowels here makes me irrationally uncomfortable

Well this is embarassing...

Is it better to set health - damage to a variable to have the equation process just once? I'm still trying to understand pass-by-value vs pass-by-reference, and whether it even applies in situations like this. Obviously the gains are essentially non-existent in this exact case.