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 comments of current node
          """
          super(NodeRelationViewMixin, self).initial(request, *args, **kwargs)
          self.node = get_object_or_404(Node, **{'slug': self.kwargs['slug']})
          self.queryset = self.model.objects.filter(node_id=self.node.id)