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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 is_closed(self) -> Optional[bool]: """For Magnet Sensor; True if Closed, False if Open."""

        if self._device_type is not None and self._device_type == DeviceType.DoorMagnet:
            return bool(self._current_status & 0x01)
        return None