def get_or_create_queryset_with_any_fallback(self) -> TypeInfo | None:
        """
        Create a QuerySet subclass with fallback to Any for unknown attributes
        and methods. This is used for the manager returned by the method above.
        """

        name = "UnknownQuerySet"

        # Check if we've already created a fallback queryset class for this
        # module, and if so reuse that.
        queryset_info = self.lookup_typeinfo(f"{self.model_classdef.info.module_name}.{name}")
        if queryset_info and queryset_info.metadata.get("django", {}).get("any_fallback_queryset"):
            return queryset_info

        base_queryset_info = self.lookup_typeinfo(fullnames.QUERYSET_CLASS_FULLNAME)
        if base_queryset_info is None:
            return None

        base_queryset = fill_typevars(base_queryset_info)
        assert isinstance(base_queryset, Instance)
        queryset_info = self.add_new_class_for_current_module(name, [base_queryset])
        queryset_info.metadata["django"] = {
            "any_fallback_queryset": True,
        }
        queryset_info.fallback_to_any = True

        queryset_info.type_vars = base_queryset_info.type_vars.copy()
        queryset_info.defn.type_vars = base_queryset_info.defn.type_vars.copy()
        queryset_info.metaclass_type = queryset_info.calculate_metaclass_type()

        return queryset_info

        Create a QuerySet subclass with fallback to Any for unknown attributes
        and methods. This is used for the manager returned by the method above.
        
mypy_django_plugin/transformers/models.py