Contextual Alternates — Change last letter

I have a typeface that only consists of numbers, and one stylistic set of numbers. I want the last number in the “line” to change to .ss01. What contextual script should I use?

Thank you!

Does this help: Features, part 4: positional alternates | Glyphs

I just found this thread, and that made it more clear to me: Noob needs to learn how to code contextual alternatives - #12 by GeorgSeifert