[Python] Is it possible to set the type of a field based on the value of another field?

I want to set and instantiate the right type based on the value of another field and get typing and autocomplete on it.

I want this to happen automatically when the class is instantiated:

TMyBackendConfig = TypeVar("TMyBackendConfig")

class MyBackendOneConfig(BaseSettings):
field_one: str = "1111111"

class MyBackendTwoConfig(BaseSettings):
field_two: str = "222222222"

class Config(BaseSettings, Generic[TMyBackendConfig]):
# backend_type: Literal["one", "two"] # want to use this to set right one
backend_config: TMyBackendConfig

def test():
_one = MyBackendOneConfig()
_two = MyBackendTwoConfig()

one = Config(backend_config=_one)
two = Config(backend_config=_one)

# I get autocomplete and typing
one.backend_config.field_one
one.backend_config.field_two


I want to be able to just do Config(backend_type="one") and get back the object with the right nested config.

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