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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, save=None):
 """Synchronously save the dataset to disk and then shut down the server. """

        if save is self.SHUTDOWN_SAVE:
            return self.execute(b'SHUTDOWN', b'SAVE')
        elif save is self.SHUTDOWN_NOSAVE:
            return self.execute(b'SHUTDOWN', b'NOSAVE')
        else:
            return self.execute(b'SHUTDOWN')