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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_range(self):
 """Return the bounds currently visible."""

        p, z = np.asarray(self.pan), np.asarray(self.zoom)
        x0, y0 = -1. / z - p
        x1, y1 = +1. / z - p
        return (x0, y0, x1, y1)