Is there a block that can tell me how many costumes a sprite has?

I want to make my own block that works like a "previous costume" block (just like the next costume block but backwards). I want to figure it out on my own, but I just need to know how to find the amount of costumes a sprite has to make it work.

You can get a list of all the costumes in a sprite with (my [costumes V]) , which you can get the length of that list to get the number of costumes.

untitled script pic

ty!

No problem