free a: bitstring.
free c,d,e:channel.
fun hash(bitstring):bitstring.

equivalence
   ! new a: bitstring; let x = hash(a) in ! out(c,x)

   ! new a:bitstring; ! out(c, hash(a))

(* EXPECTPV
RESULT Observational equivalence is true.
0.016s (user 0.012s + system 0.004s), max rss 8684K
END *)
