free c: channel.
free m,n: bitstring.

set swapping = "tag1 -> tag2".

process
    (
        out(c,m);
        sync 1 [tag1];
        out(c,choice[m,n])
    )|(
        sync 1 [tag2];
        out(c,choice[n,m])
    )

(* EXPECTPV
RESULT Observational equivalence is true.
0.020s (user 0.020s + system 0.000s), max rss 8824K
END *)
