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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 includeRect(self, r):
 """Extend rectangle to include rectangle r."""

        if not len(r) == 4:
            raise ValueError("bad sequ. length")
        self.x0, self.y0, self.x1, self.y1 = TOOLS._union_rect(self, r)
        return self