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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 _unhandled_event_default(event):
 """ Default unhandled event handler for handling simple scene navigation. """

        if isinstance(event, KeyboardEvent):
            c = event.key_code
            if c in (ord("X"), ord("x"), ord("Q"), ord("q")):
                raise StopApplication("User terminated app")
            if c in (ord(" "), ord("\n"), ord("\r")):
                raise NextScene()