protected function normalize_term($term = null)
    {
        if (null === $term) {
            return [];
        }

        if (is_int($term)) {
            $term = [$this->primary_key => $term];
        }

        if ($_term = $this->call_hook('term.after.normalized', $term)) {
            $term = $_term;
        }

        return $term;
    }