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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 start(self):
 """Begin listening for events from the Client and acting upon them. Note: If configuration has not already been loaded, it will be loaded immediately before starting to listen for events. Calling this method without having specified and/or loaded a configuration will result in completely default values being used. After all modules for this controller are loaded, the STARTUP event will be dispatched. """

        if not self.config and self.config_path is not None:
            self.load_config()
        self.running = True
        self.process_event("STARTUP", self.client, ())