IF NOT EXISTS(cl)
THEN
    RETURN(UNKNOWN);
END_IF;

IF SIZEOF(cl.definition) = 0
THEN
    RETURN(FALSE);
END_IF;

IF NOT(EXISTS(cl.definition[1]\class.its_superclass))
THEN
    RETURN(TRUE);
ELSE
    RETURN(all_class_descriptions_reachable(
        cl.definition[1]\class.its_superclass));
END_IF;