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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 zoomset_cb(self, setting, zoomlevel, fitsimage):
 """This method is called when a main FITS widget changes zoom level. """

        if not self.gui_up:
            return
        fac_x, fac_y = fitsimage.get_scale_base_xy()
        fac_x_me, fac_y_me = self.zoomimage.get_scale_base_xy()
        if (fac_x != fac_x_me) or (fac_y != fac_y_me):
            alg = fitsimage.get_zoom_algorithm()
            self.zoomimage.set_zoom_algorithm(alg)
            self.zoomimage.set_scale_base_xy(fac_x, fac_y)
        return self._zoomset(self.fitsimage_focus, zoomlevel)