Function actix_service::new_service_fn

pub fn new_service_fn<F, C, R, S, E>(
    f: F
) -> FnNewServiceNoConfig<F, C, R, S, E> where
    F: Fn() -> R,
    R: IntoFuture<Item = S, Error = E>,
    R::Item: IntoService<S>,
    S: Service, 

Create NewService for function that can produce services