Primitive E module for an XNOR gate.
We use this to implement vl2014::*vl-1-bit-xnor*.
Definition: *esim-xnor*
(defconst *esim-xnor* '(:n *esim-xnor* :x (:out ((|out| iff |a| |b|))) :i ((|a|) (|b|)) :o ((|out|))))
