def AdjustTZ(self):
        """ run astimezone() on all contained dates to align them with the activity TZ (requires non-naive DTs) """
        if self.TZ is None:
            raise ValueError("TZ not set")
        self.StartTime = self.StartTime.astimezone(self.TZ)
        self.EndTime = self.EndTime.astimezone(self.TZ)

        for lap in self.Laps:
            lap.StartTime = lap.StartTime.astimezone(self.TZ)
            lap.EndTime = lap.EndTime.astimezone(self.TZ)
            for wp in lap.Waypoints:
                    wp.Timestamp = wp.Timestamp.astimezone(self.TZ)
        self.CalculateUID()
 run astimezone() on all contained dates to align them with the activity TZ (requires non-naive DTs) 
tapiriik/services/interchange.py