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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 shutdown(self, status='SUCCEEDED', diagnostics=None):
 """Shutdown the application. Stop all running containers and shutdown the application. Parameters status : FinalStatus, optional The final application status. Default is 'SUCCEEDED'. diagnostics : str, optional The application exit message, usually used for diagnosing failures. Can be seen in the YARN Web UI for completed applications under "diagnostics", as well as the ``diagnostic`` field of ``ApplicationReport`` objects. If not provided, a default will be used. """

        req = proto.ShutdownRequest(final_status=str(FinalStatus(status)),
                                    diagnostics=diagnostics)
        self._call('shutdown', req)