new_contents: from argparse import ArgumentParser
  
  from . import Backlight
  
  
  def _create_argument_parser():
      parser = ArgumentParser(
          description='Get/set power and brightness of the official Raspberry Pi 7" touch display.'
      )
      parser.add_argument(
          "sysfs_path",
          metavar="SYSFS_PATH",
          type=str,
          nargs="?",
          default=None,
          help="Optional path to the backlight sysfs, set to :emulator: to use with rpi-backlight-emulator",
      )
      parser.add_argument(
          "--get-brightness",
          action="store_true",
          help="get the display brightness (0-100)",
      )
      parser.add_argument(
          "-b",
          "--set-brightness",
          metavar="VALUE",
          type=int,
          choices=range(0, 101),
          help="set the display brightness (0-100)",
      )
      parser.add_argument(
          "--get-power", action="store_true", help="get the display power (on/off)"
      )
      parser.add_argument(
          "-p",
          "--set-power",
          metavar="VALUE",
          type=str,
          choices=("on", "off"),
          help="set the display power (on/off)",
      )
      parser.add_argument(
          "-d", "--duration", type=float, default=0, help="fading duration in seconds"
      )
      return parser
  
  
  def main():
      """Start the command line interface."""
      parser = _create_argument_parser()
      args = parser.parse_args()
  
      if args.sysfs_path is not None:
          backlight = Backlight(backlight_sysfs_path=args.sysfs_path)
      else:
          backlight = Backlight()
  
      if args.get_brightness:
          if any((args.set_brightness, args.get_power, args.set_power, args.duration)):
              parser.error("--get-brightness must be used without other options")
          print(backlight.brightness)
          return
  
      if args.get_power:
          if any(
              (args.get_brightness, args.set_brightness, args.set_power, args.duration)
          ):
              parser.error("--get-power must be used without other options")
          print("on" if backlight.power else "off")
          return
  
      if args.set_brightness:
          if any((args.get_brightness, args.get_power, args.set_power)):
              parser.error(
                  "-b/--set-brightness must be used without other options except for -d/--duration"
              )
          backlight.brightness = args.set_brightness
          return
  
      if args.set_power:
          if any(
              (args.get_brightness, args.set_brightness, args.get_power, args.duration)
          ):
              parser.error("-p/--set-power must be used without other options")
          backlight.power = True if args.set_power == "on" else False
          return
  
      if args.duration:
          parser.error("-d/--duration must be used with -b/--set-brightness")
  
subject: Add CLI