code: def show_announcement_view(request):
      
      if request.method == "POST":
          announcement_id = request.POST.get("announcement_id")
          if announcement_id:
              announcement = Announcement.objects.get(id=announcement_id)
              announcement.user_map.users_hidden.remove(request.user)
              announcement.user_map.save()
              return http.HttpResponse("Unhidden")
          raise http.Http404
      else:
          return http.HttpResponseNotAllowed(["POST"], "HTTP 405: METHOD NOT ALLOWED")
docs: Unhide an announcement that was hidden by the logged-in user.
  
          announcements_hidden in the user model is the related_name for
          "users_hidden" in the announcement model.