docs: def hook_get_results(self, changelist):
          """Triggered by `ChangeList.get_results()`."""
  
          # Poor NestedSet guys they've punished themselves once chosen that approach,
          # and now we punish them again with all those DB hits.
  
          result_list = list(changelist.result_list)
  
          # Get children stats.
          filter_kwargs = {'%s' % self.left_field: models.F('%s' % self.right_field) - 1}  # Leaf nodes only.
          filter_kwargs.update(self.get_immediate_children_filter(self.parent))
  
          stats_qs = changelist.result_list.filter(**filter_kwargs).values_list('id')
          leafs = [item[0] for item in stats_qs]
  
          for result in result_list:
  
              if result.id in leafs:
                  setattr(result, self.CHILD_COUNT_MODEL_ATTR, 0)
              else:
                  setattr(result, self.CHILD_COUNT_MODEL_ATTR, '>1')  # Too much pain to get real stats, so that'll suffice.
  
          if self.pid:
              # Render to upper level link.
              parent = self.parent
  
              filter_kwargs = {
                  '%s__lt' % self.left_field: getattr(parent, self.left_field),
                  '%s__gt' % self.right_field: getattr(parent, self.right_field),
              }
  
              try:
                  granparent_id = changelist.model.objects.filter(**filter_kwargs).order_by('-%s' % self.left_field)[0].id
              except IndexError:
                  granparent_id = None
  
              if granparent_id != parent.id:
                  parent = changelist.model(pk=granparent_id)
  
              setattr(parent, self.UPPER_LEVEL_MODEL_ATTR, True)
              result_list = [parent] + result_list
  
          changelist.result_list = result_list