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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def listen(self, event):
 """Request that the Controller listen for and dispatch an event. Note: Even if the module that requested the listening is later unloaded, the Controller will continue to dispatch the event, there just might not be anything that cares about it. That's okay. """

        if event in self.registered:
            # Already listening to this event
            return
        def handler(client, *args):
            return self.process_event(event, client, args)
        self.client.add_handler(event, handler)
        self.registered.add(event)
        _log.debug("Controller is now listening for '%s' events", event)