GraphQL\Examples\Blog\Data\DataSource::findLastStoryFor PHP Method

    public static function findLastStoryFor($authorId)
    {
        $storiesFound = array_filter(self::$stories, function (Story $story) use($authorId) {
            return $story->authorId == $authorId;
        });
        return !empty($storiesFound) ? $storiesFound[count($storiesFound) - 1] : null;
    }

 public function lastStoryPosted(User $user)
 {
     return DataSource::findLastStoryFor($user->id);
 }