code: def get_queryset(self):
          
          if self.queryset is None:
              if self.model:
                  return self.model._default_manager.all()
              else:
                  raise ImproperlyConfigured(
                      "%(cls)s is missing a QuerySet. Define "
                      "%(cls)s.model, %(cls)s.queryset, or override "
                      "%(cls)s.get_queryset()." % {
                          'cls': self.__class__.__name__
                      }
                  )
          return self.queryset.all()
docs: Return the `QuerySet` that will be used to look up the object.
          Note that this method is called by the default implementation of
          `get_object` and may not be called if `get_object` is overridden.