Primitive E module for a tri-state buffer.
We use this to implement vl2014::*vl-1-bit-zmux*.
Definition: *esim-tri*
(defconst *esim-tri* '(:n *esim-tri* :x (:out ((|out| tristate |sel| |a|))) :i ((|sel|) (|a|)) :o ((|out|))))
