public function lowerPrecedenceThan($other)
    {
        if (!($other instanceof ExpressionNode)) return false;

        if ($this->getPrecedence() < $other->getPrecedence()) return true;
        if ($this->getPrecedence() > $other->getPrecedence()) return false;

        if ($this->associativity == self::LEFT_ASSOC) return true;

        return false;

    }