These three data types are used to represent existential types, according to the docs.
My first thought would be to use it to reference a contract of unknown type e.g.
template Foo with bar : ContractId AnyTemplate ...
But this doesn’t work because it’s not serializable.
It’s not clear to me how these can be used in practice. Could you give an example?
If they’re not meant for general consumption, maybe we should
-- | HIDE them in the docs.