def proximal(self):
        """Return the `proximal factory` of the functional.

        See Also
        --------
        odl.solvers.nonsmooth.proximal_operators.proximal_convex_conj_kl_cross_entropy :
            `proximal factory` for convex conjugate of the KL cross entropy.
        odl.solvers.nonsmooth.proximal_operators.proximal_convex_conj :
            Proximal of the convex conjugate of a functional.
        """
        return proximal_convex_conj(proximal_convex_conj_kl_cross_entropy(
            space=self.domain, g=self.prior))