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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 highest_stored_id(self):
 """Scan through the stored readings and report the highest stored id. Returns: int: The highest stored id. """


        shared = [0]
        def _keep_max(_i, reading):
            if reading.reading_id > shared[0]:
                shared[0] = reading.reading_id

        self.engine.scan_storage('storage', _keep_max)
        self.engine.scan_storage('streaming', _keep_max)

        return shared[0]