Python 2.x/3.x example code for a ``Sum`` server and client.
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Save this in to a file ``sum_server.py``::

    # Server implementation for a "Sum" command which adds two integers
    from twisted.protocols import amp
    from twisted.internet import reactor
    from twisted.internet.protocol import Factory
    
    class Sum(amp.Command):
        # normally shared by client and server code
        arguments = [(b'a', amp.Integer()),
                     (b'b', amp.Integer())]
        response = [(b'total', amp.Integer())]
    
    class Protocol(amp.AMP):
        @Sum.responder
        def sum(self, a, b):
            return {'total': a+b}
    
    pf = Factory()
    pf.protocol = Protocol
    reactor.listenTCP(1234, pf) # listen on port 1234
    reactor.run()

Save this in to a file ``sum_client.py``::

    from twisted.internet import reactor
    from twisted.internet.protocol import ClientCreator
    from twisted.protocols import amp
    
    class Sum(amp.Command):
        # normally shared by client and server code
        arguments = [(b'a', amp.Integer()),
                     (b'b', amp.Integer())]
        response = [(b'total', amp.Integer())]
    
    def connected(protocol):
        return protocol.callRemote(Sum, a=13, b=81
            ).addCallback(gotResult)
    
    def gotResult(result):
        print('total: %d' % (result['total'],))
        reactor.stop()
    
    def error(reason):
        print("Something went wrong")
        print(reason)
        reactor.stop()
    
    ClientCreator(reactor, amp.AMP).connectTCP(
        '127.0.0.1', 1234).addCallback(connected).addErrback(error)
    
    reactor.run()

Open two terminal windows. In the first, type this::

    python sum_server.py

Then in the second, type::

    python sum_client.py

*The result of the addition should be printed on your screen!*