private static function createCustomizerFeedItems(
        AdWordsServices $adWordsServices,
        AdWordsSession $session,
        AdCustomizerFeed $adCustomizerFeed,
        array $adGroupIds
    ) {
        $feedItemService = $adWordsServices->get($session, FeedItemService::class);

        $operations = [];

        $marsDate = mktime(0, 0, 0, date('m'), 1, date('Y'));
        $venusDate = mktime(0, 0, 0, date('m'), 15, date('Y'));

        // Create multiple feed item operations and add them to the operations list.
        $operations[] = self::createFeedItemAddOperation(
            'Mars',
            '$1234.56',
            date('Ymd His', $marsDate),
            $adCustomizerFeed
        );
        $operations[] = self::createFeedItemAddOperation(
            'Venus',
            '$1450.00',
            date('Ymd His', $venusDate),
            $adCustomizerFeed
        );

        $result = $feedItemService->mutate($operations);

        foreach ($result->getValue() as $feedItem) {
            printf(
                'FeedItem with ID %d was added.%s',
                $feedItem->getFeedItemId(),
                PHP_EOL
            );
        }
        for ($i = 0; $i < count($result->getValue()); $i++) {
            // Add feed item targeting to restrict the feed item to specific ad
            // groups.
            self::restrictFeedItemToAdGroup(
                $adWordsServices,
                $session,
                $result->getValue()[$i],
                $adGroupIds[$i]
            );
        }
    }