Adding type hints to Python's **kwargs

Using python TypedDict and Unpack, we can add types to any function that accepts variable-length keyword arguments

from typing import TypedDict
from typing import Unpack # python3.11

# if you're on python3.10 or lower
# from typing_extensions import Unpack

class AKwargs(TypedDict):
    name: str
    age: int


def a(**kwargs: Unpack[AKwargs]):
    pass

Your editor’s language server will alert you if there are any errors in input to the function. Here’s how pylance reports it.

Here’s how mypy reports the error

❯ mypy t.py --enable-incomplete-feature=Unpack
t.py:15: error: Missing named argument "name" for "a"  [call-arg]
t.py:15: error: Missing named argument "age" for "a"  [call-arg]
Found 2 errors in 1 file (checked 1 source file)

And when you add an unknown parameter,