docs: def create_or_update_groups(self):
          """Add/Deletes group model instances to match the
          the given list of group names.
          """
  
          for name in self.group_names:
              try:
                  Group.objects.get(name=name)
              except ObjectDoesNotExist:
                  Group.objects.create(name=name)
          Group.objects.exclude(name__in=self.group_names).delete()
  
          if self.verbose:
              names = [obj.name for obj in Group.objects.all().order_by("name")]
              sys.stdout.write(f"  Groups are: {', '.join(names)}\n")