// "inv-16.hac" should pass
// copy-modified from "inv-14.hac"
// just instantiating an inverter.  

defproc inv(bool a, b) {
prs {
	a -> b-
	~a -> b+
}
}

bool x, y, p, q;
inv i1(x, y);
inv i2(p, );
inv i3(, q);

