def METHOD_NAME(self):
    """ Add vdd/gnd rails to the top, (middle), and bottom. """
    if OPTS.tech_name == "sky130":
        for name in ["vdd", "gnd"]:
            for inst in [self.nand_inst, self.inv_inst]:
                self.copy_layout_pin(inst, name)
    else:
        self.add_layout_pin_rect_center(text="gnd",
                                        layer=self.route_layer,
                                        offset=vector(0.5 * self.width, 0),
                                        width=self.width)
        self.add_layout_pin_rect_center(text="vdd",
                                        layer=self.route_layer,
                                        offset=vector(0.5 * self.width, self.height),
                                        width=self.width)