Stars and bars (multisets)

I was looking for a Julia implementation of this known combinatorics problem: [Stars and bars](https://en.wikipedia.org/wiki/Stars_and_bars_%28combinatorics%29)

I have some struggle to use `multiset_combinations` and `multiset_permutations` and I didn't find any good documentation on it.

I wanted to compute/enumerate a multiset number using this method. However, It seems that `multiset_combinations` is performing a combination on multisets, which is something very different. I'm still new to Julia so I might be wrong.

Also, If you can point me to a workaround for this problem, I'll be glad to hear it!