Change function signature in Python

change_function_signature.py

import inspect

def f1(a1: int, k1: str="v1", k2: str="v2") -> None:
    print("f1", a1, k1, k2)

def f2(a2: int) -> int:
    print("f2", a2)
    return a2 + 1

def f3(a3: int, **kwargs: str) -> None:
    f1((f2(a3)), **kwargs)

new_params = [
    *[
        p for p in inspect.signature(f3).parameters.values()
        if p.kind is not p.VAR_KEYWORD
    ],
    *[
        p for p in inspect.signature(f1).parameters.values()
        if p.default is not inspect.Parameter.empty
    ],
]
new_signature = inspect.signature(f3).replace(parameters=new_params)

print(inspect.signature(f1))
# (a1: int, k1: str = 'v1', k2: str = 'v2') -> None
print(inspect.signature(f3))
# (a3: int, **kwargs: str) -> None
f3.__signature__ = new_signature
print(inspect.signature(f3))
# (a3: int, k1: str = 'v1', k2: str = 'v2') -> None