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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 width_max(self, width_max):
 """Set the maximum width of the widget. Parameters width_max: None | float the maximum width of the widget. if None, maximum width is unbounded """

        if width_max is None:
            self._width_limits[1] = None
            return

        width_max = float(width_max)
        assert(self.width_min <= width_max)

        self._width_limits[1] = width_max
        self._update_layout()