Remove __del__ from SangaStage class

        """De-energise the stepper motor coils"""

        self.board.release_motors()

    def __del__(self):

        """Close the port when the object is deleted

        NB if the object is created in a with statement, this will cause

        the port to be closed at the end of the with block."""

        self.close()

    def __enter__(self):

        """When we use this in a with statement, remember where we started."""

        self._position_on_enter = self.position