How can you test if a document Id (integer) is valid ? How can you test if this

This rule returns true if the id points to a valid document
=index(split(getcontentobjectdetailsbyid(ri!id), "Type: "), 2, "") = "Document"

I found this in the following post:
forum.appian.com/.../e-91772

To test if a document exists, you can also use the following expression:
=exact(getcontentobjectdetailsbyid(cons!Document), "No object with this internal name has been found")

Please view the following post:
forum.appian.com/.../e-124579