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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 start_time(self):
 """ getter and setter the measurement start timestamp Returns ------- timestamp : datetime.datetime start timestamp """


        timestamp = self.abs_time / 10 ** 9
        if self.time_flags & v4c.FLAG_HD_LOCAL_TIME:
            timestamp = datetime.fromtimestamp(timestamp)
        else:
            timestamp = datetime.fromtimestamp(timestamp, timezone.utc)

        return timestamp