Returns
        -------
        prior_prior_model_dict: {Prior: PriorModel}
            A dictionary mapping priors to associated prior models. Each prior will only have one prior model; if a
            prior is shared by two prior models then one of those prior models will be in this dictionary.

def prior_prior_model_dict(self):
        """
        Returns
        -------
        prior_prior_model_dict: {Prior: PriorModel}
            A dictionary mapping priors to associated prior models. Each prior will only have one prior model; if a
            prior is shared by two prior models then one of those prior models will be in this dictionary.
        """
        return {prior: prior_model[1] for prior_model in self.prior_model_tuples for _, prior in
                prior_model[1].prior_tuples}