def psi2n(self, Z, variational_posterior):
return self.psicomp.psicomputations(self, Z, variational_posterior, return_psi2_n=True)[<NUM_LIT:2>]<EOL>
.. math::
    \psi_2^{n,m,m'} = E_{q(X)}[ k(Z_m, X_n) k(X_n, Z_{m'})]

Thus, we do not sum out n, compared to psi2