Learn how to use Python’s optional type-hinting syntax to create cleaner and more useful code.

It is possible that new versions of Python, like 3.12 will have ways to set the limit at a finer level (e.g. thread local variable or context manager). Why not keyword parameter of int? Having a ...

As you can see, the interpreter will check whether the first argument is an instance of function's class, so the integer 1 can't pass. But the thing differs in CPython 3 implemention.