Why should type annotation be enforced at run time? In statically typed languages there is no type checking at run time, your type system already proved the type of variable.
> That’s why, for example, they can’t be used to increase the performance of the interpreter.
They can (as in - there's API for that, the rest is up to a community effort) improve performance of a final program, if type-annotated code is passed through Cython with ``annotation_typing=True`` flag:
