def thread_list(request, board_code):
    # id for all existing threads
    num_threads = [a.thread_id for a in Post.objects.filter(op=True, board__code=board_code)]
    posts = []
    for a in num_threads:
        thread = Thread.objects.filter(id=a).get()
        posts.append(thread.last_posts())

    sorted_posts = []
    last_post = Post.objects.filter(board__code=board_code)[:1].get()
    for li in posts:
        for a in li:
            if a == last_post:
                sorted_posts.append(li)
    for li in posts:
        if li not in sorted_posts:
            sorted_posts.append(li)
    return render(request, 'board/thread_list.html', {'sorted_posts': sorted_posts})

#models.py

    def last_posts(self):
        res = self.post_set.filter(Q(op=True) | Q(id__in=[a.id for a in self.post_set.all()[:3]]))
        return res[::-1]