docs: def initial(self, request, *args, **kwargs):
          """
          Custom initial method:
              * ensure node exists and store it in an instance attribute
              * change queryset to return only images of current node
          """
          super(NodeImageList, self).initial(request, *args, **kwargs)
          # ensure node exists
          self.node = get_queryset_or_404(
              Node.objects.published().accessible_to(request.user),
              {'slug': self.kwargs['slug']}
          )
          # check permissions on node (for image creation)
          self.check_object_permissions(request, self.node)