public function filterByZip($zip = null, $comparison = null)
    {
        if (null === $comparison) {
            if (is_array($zip)) {
                $comparison = Criteria::IN;
            } elseif (preg_match('/[\%\*]/', $zip)) {
                $zip = str_replace('*', '%', $zip);
                $comparison = Criteria::LIKE;
            }
        }

        return $this->addUsingAlias(CustomerPeer::ZIP, $zip, $comparison);
    }