From the documentation class typing.Union Union type; Union[X, Y] means either X or Y. Hence the proper way to represent more than one return data type is from typing import Union def foo(client_id: str) -> Union[list,bool] But do note that typing is not enforced. Python continues to remain a dynamically-typed language. The annotation syntax has … Read more
Your second way is correct. def foo(opts: dict = {}): pass print(foo.__annotations__) this outputs {‘opts’: <class ‘dict’>} It’s true that’s it’s not listed in PEP 484, but type hints are an application of function annotations, which are documented in PEP 3107. The syntax section makes it clear that keyword arguments works with function annotations in … Read more
TL;DR: As of today (2019), in Python 3.7+ you can turn this feature on using a “future” statement, from __future__ import annotations. (The behaviour enabled by from __future__ import annotations might become the default in future versions of Python, and was going to be made the default in Python 3.10. However, the change in 3.10 … Read more