Function actix_service::apply_cfg

pub fn apply_cfg<F, C, T, R, S>(
    srv: T, 
    f: F
) -> impl NewService<Config = C, Request = S::Request, Response = S::Response, Error = S::Error, Service = S, InitError = R::Error> + Clone where
    F: FnMut(&C, &mut T) -> R,
    T: Service,
    R: IntoFuture,
    R::Item: IntoService<S>,
    S: Service, 

Convert Fn(&Config, &mut Service) -> Future<Service> fn to a NewService