Richard Cook

Thanks. I will take care of this.

I'm not sure what the meaning of multiset with 0 or negative occurrences is. This change would make a break with the mathematical concept of multiset (https://en.wikipedia.org/wiki/Multiset) where the multiplicity...

If it were to have a name other than `MultiSet` (`FreeAbelianGroup`, maybe?), we would probably want to maximize the amount of code shared by the implementations. And write some tests!...

Looks like something like this already exists: https://hackage.haskell.org/package/signed-multiset. They're using the name "signed multiset".

This repo is just a series of demo programs demonstrating how to use the [amazonka][https://github.com/brendanhay/amazonka] family of Haskell packages. That failure indicates that some asynchronous process has not completed yet...