Python ZeroMQ Device Blocking -- Why?

gistfile1.py

# SOLVED, thanks to Chuck Remes -- I was using zmq.QUEUE instead of zmq.STREAMER
 
pd = ProcessDevice(zmq.STREAMER, zmq.PUSH, zmq.PULL)
pd.bind_in("tcp://127.0.0.1:6000")
pd.bind_out("tcp://127.0.0.1:6001")
pd.start()

def client():
    context = zmq.Context()
    socket = context.socket(zmq.PUSH)
    socket.connect("tcp://127.0.0.1:6000")

    for i in xrange(0,10):
        print "inside client loop"
        socket.send('sending message #%s' % i)

def worker():
    context = zmq.Context()
    socket = context.socket(zmq.PULL)
    socket.connect("tcp://127.0.0.1:6001")
    
    for i in xrange(0,10):
        print "inside worker loop"
        message = socket.recv()
        print "got message! %s" % message


client()
worker()
pd.join()