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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 _order_decorations(self):
 """Order decorations according draw_order and size of selection. Highest draw_order will appear on top of the lowest values. If draw_order is equal,smaller selections are draw in top of bigger selections. """

        def order_function(sel):
            end = sel.cursor.selectionEnd()
            start = sel.cursor.selectionStart()
            return sel.draw_order, -(end - start)

        self._decorations = sorted(self._decorations,
                                   key=order_function)