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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 left(self, expand=None):
 """ Returns a new Region left of the current region with a width of ``expand`` pixels. Does not include the current region. If range is omitted, it reaches to the left border of the screen. The new region has the same height and y-position as the current region. """

        if expand == None:
            x = 0
            y = self.y
            w = self.x
            h = self.h
        else:
            x = self.x-expand
            y = self.y
            w = expand
            h = self.h
        return Region(x, y, w, h).clipRegionToScreen()