docs: def _gen_packet_setpower(self, sequence, power, fade):
          """ Generate "setpower" packet payload. """
          level = pack("<H", Power.BULB_OFF if power == 0 else Power.BULB_ON)
          duration = pack("<I", fade)
  
          # assemble payload
          payload = bytearray(level)
          payload.extend(duration)
  
          return self._gen_packet(sequence, PayloadType.SETPOWER2, payload)