public function formatDefault($value) {
        if ($value === '') {
            return '';
        }

        if ($value instanceof Closure) {
            $value = call_user_func($value, $this);

        } else if (is_string($value) || $value === null) {
            $value = $this->getDriver()->escape($value);
        }

        return sprintf($this->getClause(self::DEFAULT_TO), $value);
    }