text: from django.shortcuts import render
  
  
  def handler403(request):
      return render(request, '403.html', status=403)
  
  
  def handler404(request):
      return render(request, '404.html', status=404)
  
  
  def handler500(request):
      return render(request, '500.html', status=500)
  
  
  def sort_queryset(queryset, request, allowed_sorts, default=None):
      """ Sorts the queryset by one of allowed_sorts based on parameters
      'sort' and 'dir' from request """
      sort = request.GET.get('sort', None)
      if sort in allowed_sorts:
          direction = request.GET.get('dir', 'asc')
          sort = ('-' if direction == 'desc' else '') + sort
          queryset = queryset.order_by(sort)
      elif default:
          queryset = queryset.order_by(default)
      return queryset
  