return (s1.hashCode() < s2.hashCode()) || (s1.hashCode() == s2.hashCode() && s1.isLess(s2));
return s1.isLess(s2);
    private boolean less(Symbol s1, Symbol s2) {        return (s1.hashCode() < s2.hashCode())            || (s1.hashCode() == s2.hashCode() && s1.isLess(s2));    }