resolve asyncsrv.pl issue, the original example doesn't work!

asyncsrv.pl

60c59,69
<         zmq.device(zmq.QUEUE, frontend, backend)
---
>         while True:
>             sockets = dict(poll.poll())
>             if frontend in sockets:
>                 if sockets[frontend] == zmq.POLLIN:
>                     msg = frontend.recv()
>                     print 'Server received %s' % (msg)
>                     backend.send(msg)
>             if backend in sockets:
>                 if sockets[backend] == zmq.POLLIN:
>                     msg = backend.recv()
>                     frontend.send(msg)
77d85
<             src = worker.recv()
83d90
<                 worker.send(src, zmq.SNDMORE)