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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 set_polar_box(self, rmin=0, rmax=1, tmin=0, tmax=2 * pi):
 """Helper for polar charts"""

        self._rmin = rmin
        self._rmax = rmax
        self._tmin = tmin
        self._tmax = tmax
        self.xmin = self.ymin = rmin - rmax
        self.xmax = self.ymax = rmax - rmin