public function set_request_token_secret(array $identifiers, $secret) {

        if (empty($identifiers) || empty($identifiers['caller'])) {
            throw new coding_exception('Invalid call identification');
        }

        $cache = cache::make_from_params(cache_store::MODE_SESSION, 'core', 'flickrclient', $identifiers);
        $cache->set('request_token_secret', $secret);
    }