bar.py

from typing import Dict, Union
QueryDict = Dict[str, Union[str, int, None]]

def foo(extra_query: QueryDict = None):
    f = {"a":1, "b":2}
    if extra_query:
        f.update(extra_query)


foo(extra_query={"c": 3})

the error is:

bar.py:7: error: Argument 1 to "update" of "dict" has incompatible type "Dict[str, Union[str, int, None]]"; expected "Mapping[str, int]"