Fast API Tutorial, Part 28: Middleware and CORS

For me, it shows the following : Unresolved attribute reference 'add_middleware' for class 'app'

need a help, lets say my api is deployed on aks.. my localhost fast api works fine with localhost webapp. but the deployed one is not working with localhost webapp due to cors issue. Added origin localhost to cors middleware, still no luck
how to fix that

What about csrf_tokens do these need to be handled also? I know in django it is quite easy with {% csrf_token %} but what about for fastapi?