## Christmas Cookies

It's December 1st! That means it's almost time for the big day! Santa has a preparation regimen that involves, of course, eating lots of delicious cookies.

Santa's elves have provided Santa an API whereby Santa can submit his favorite cookie flavors. This year his favorites are:

- `ginger-bread`
- `chocolate-chip`

But the elves have some kind of fancy code-gen build step (built in Rust, of course), so all Santa needs to do is update the `SantasFavoriteCookies` type to accept either of his favorite cookies.

Can you help?
