Wrapper function for selecting appropriate latent variable for variational inference

        Parameters
        ----------
        index : int
            0 or 1 depending on which latent variable

        Returns
        ----------
        The appropriate indexed parameter

def vi_return_param(self, index):
        """ Wrapper function for selecting appropriate latent variable for variational inference

        Parameters
        ----------
        index : int
            0 or 1 depending on which latent variable

        Returns
        ----------
        The appropriate indexed parameter
        """
        if index == 0:
            return self.mu0
        elif index == 1:
            return np.log(self.sigma0)