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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 get_llur(self):
 """ Get lower-left and upper-right coordinates of the bounding box of this compound object. Returns ------- x1, y1, x2, y2: a 4-tuple of the lower-left and upper-right coords """

        points = np.array([obj.get_llur() for obj in self.objects])
        t_ = points.T
        x1, y1 = t_[0].min(), t_[1].min()
        x2, y2 = t_[2].max(), t_[3].max()
        return (x1, y1, x2, y2)