free c:channel.
const a:bitstring.
const b:bitstring.
fun h(bitstring):bitstring.
fun f(bitstring):bitstring.
fun g(bitstring,bitstring,bitstring):bitstring.

event e1(bitstring).
event e2(bitstring).

query x:bitstring; event(e1(x)) ==> x <> a || x = a.

process
  in(c,y:bitstring);
  event e1(y);
  out(c,y)

(* EXPECTPV
RESULT event(e1(x)) ==> x ≠ a || x = a is true.
0.004s (user 0.004s + system 0.000s), max rss 7308K
END *)
