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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 mass_fraction_within_radius(self, kwargs_lens, center_x, center_y, theta_E, numPix=100):
 """ computes the mean convergence of all the different lens model components within a spherical aperture :param kwargs_lens: lens model keyword argument list :param center_x: center of the aperture :param center_y: center of the aperture :param theta_E: radius of aperture :return: list of average convergences for all the model components """

        x_grid, y_grid = util.make_grid(numPix=numPix, deltapix=2.*theta_E / numPix)
        x_grid += center_x
        y_grid += center_y
        mask = mask_util.mask_sphere(x_grid, y_grid, center_x, center_y, theta_E)
        kappa_list = []
        for i in range(len(kwargs_lens)):
            kappa = self.LensModel.kappa(x_grid, y_grid, kwargs_lens, k=i)
            kappa_mean = np.sum(kappa * mask) / np.sum(mask)
            kappa_list.append(kappa_mean)
        return kappa_list