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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 fov(self):
 """ Get the field of view in degrees. Returns fov : (2,) float XY field of view in degrees """

        if self._fov is None:
            fov = [2.0 * np.degrees(np.arctan((px / 2.0) / f))
                   for px, f in zip(self._resolution, self._focal)]
            fov = np.asanyarray(fov, dtype=np.float64)
            self._fov = fov
        return self._fov