Function actix_service::apply_cfg

pub fn apply_cfg<F, C, T, R, S, E>(
    srv: T, 
    f: F
) -> impl ServiceFactory<Config = C, Request = S::Request, Response = S::Response, Error = S::Error, Service = S, InitError = E, Future = R> + Clone where
    F: FnMut(C, &mut T) -> R,
    T: Service,
    R: Future<Output = Result<S, E>>,
    S: Service, 

Convert Fn(Config, &mut Service1) -> Future<Service2> fn to a service factory