typing module

typing exists purely so type-annotated code can import it without ModuleNotFoundError. No runtime type checking happens. The forms are inert marker objects; subscripting them (list[int], Optional[str], Union[int, str]) returns a placeholder value but does not validate anything.

Names defined

Any, Optional, Union, List, Dict, Tuple, Set, FrozenSet, Callable, Type, Sequence, Mapping, Iterable, Iterator, Generator, ClassVar, Final, Literal, TypeVar, Generic, Protocol, Annotated, Self, Never, NoReturn, TYPE_CHECKING.

TYPE_CHECKING is False (as in CPython at runtime).

Not implemented

• get_type_hints, get_args, get_origin, cast, assert_type, assert_never, overload, final, runtime_checkable, NewType, NamedTuple, TypedDict, dataclass_transform, ParamSpec, Concatenate, Unpack, TypeAlias, TypeAliasType, LiteralString.
• Any introspection of annotations: __annotations__ is not populated on functions or modules, so libraries that read it (Pydantic, attrs, inspect-based code) cannot run.

If you need real type validation, do it on the host side around the sandbox boundary.