(I'd have to figure out how to do the code equation stuff to make this
type actually usable the way nat is, but it should behave correctly in
proofs)

(do not actually use this, most things are broken, and the primitives
lib barely exists and is simply incorrect. But it is enough to create
syntax-correct Isabelle code for relatively simply rust code, as long
as it does not contain any uses of traits)

It's redundant with `item_meta.name`