public function mustBeKept($tweetId)
    {
        if (count($this->getRetweetingStatuses()) == 0) {
            // This tweet has not been retweeted
            return false;
        }

        // Check that this tweet has not been retweeted after $tweetId
        foreach ($this->getRetweetingStatuses() as $retweeting_status) {
            // This tweet is retweeted in the timeline, keep it
            if ($retweeting_status->getId() >= $tweetId) {
                return true;
            }
        }

        return false;
    }