'Method for a time consuming task.
This function must return a deferred. If it is successfull,
a `basic.ack` will be sent to AMQP. If the task was not completed a
`basic.nack` will be sent. In this example it will always return
successfully after a 2 second pause.'

def task(self, msg):

    return task.deferLater(reactor, 2, (lambda : log.msg('task    completed')))
