Machinery that creates type annotations and interacting with type annotations (Any / cast / get_args)
Stuff that gets injected into the global namespace(like None), also contains things that are not accessible(like NoneType)
exposes some of the hidden things from builtins
Abstract base classes for the standard collections and functions (Sequence / Coroutine / Callable)
type stubs for the stdlib and third party modules
a module that only exists at type time and contains some helper types and type stubs for things in builtins (like NoneType)