Primitive E module for identity assignment.
We use this to implement vl2014::*vl-1-bit-assign*. This differs from a BUF in that it does not coerce Z into X. There is probably not any way to actually implement this in hardware.
(defconst *esim-id* '(:n *esim-id* :x (:out ((|out| . |in|))) :i ((|in|)) :o ((|out|))))