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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 add_station(self, lv_station):
 """Adds a LV station to _station and grid graph if not already existing"""

        if not isinstance(lv_station, LVStationDing0):
            raise Exception('Given LV station is not a LVStationDing0 object.')
        if self._station is None:
            self._station = lv_station
            self.graph_add_node(lv_station)
            self.grid_district.lv_load_area.mv_grid_district.mv_grid.graph_add_node(lv_station)