def undo ( self ):
        """ Undoes the change.
        """
        history = self.history
        for i in range( 1 - history.now, -1, -1 ):
            items = history.history[i]
            for j in range( len( items ) - 1, -1, -1 ):
                items[j].undo()

    #---------------------------------------------------------------------------
    #  Re-does the change:
    #---------------------------------------------------------------------------
dataset/ETHPy150Open enthought/traitsui/traitsui/undo.py/UndoHistoryUndoItem.undo/swapped operands of `-`