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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 inner_rect(self):
 """The rectangular area inside the margin, border, and padding. Generally widgets should avoid drawing or placing sub-widgets outside this rectangle. """

        m = self.margin + self._border_width + self.padding
        if not self.border_color.is_blank:
            m += 1
        return Rect((m, m), (self.size[0]-2*m, self.size[1]-2*m))