BEGIN;

CREATE FUNCTION is_name(value TEXT) RETURNS BOOLEAN LANGUAGE plpgsql AS $$
BEGIN
    RETURN value = btrim(value) AND length(value) > 0;
END;
$$;

CREATE FUNCTION is_language_code(value VARCHAR) RETURNS BOOLEAN LANGUAGE plpgsql
AS $$
BEGIN
    RETURN value ~ '^[a-z]{2}$';
END;
$$;

COMMIT;