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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 stop_periodic_snapshots(self):
 """ Post a stop signal to the thread that takes the periodic snapshots. The function waits for the thread to terminate which can take some time depending on the configured interval. """

        if self._periodic_thread and self._periodic_thread.isAlive():
            self._periodic_thread.stop = True
            self._periodic_thread.join()
            self._periodic_thread = None