def dflt_interval(self, cd_id: str) -> (int, int):
        LOGGER.debug('RevocationCache.dflt_interval >>>')
        fro = None
        to = None
        for rr_id in self:
            if cd_id != rev_reg_id2cred_def_id(rr_id):
                continue
            entry = self[rr_id]
            if entry.rr_delta_frames:
                to = max(entry.rr_delta_frames, key=lambda f: f.to).to
                fro = min(fro or to, to)
        if not (fro and to):
            LOGGER.debug(
                'RevocationCache.dflt_interval <!< No data for default non-revoc interval on cred def id %s',
                cd_id)
            raise CacheIndex('No data for default non-revoc interval on cred def id {}'.format(cd_id))
        rv = (fro, to)
        LOGGER.debug('RevocationCache.dflt_interval <<< %s', rv)
        return rv