Function actix_service::apply_fn_factory

pub fn apply_fn_factory<T, F, R, In, Out, Err, U>(
    service: U, 
    f: F
) -> ApplyServiceFactory<T, F, R, In, Out, Err> where
    T: ServiceFactory<Error = Err>,
    F: FnMut(In, &mut T::Service) -> R + Clone,
    R: Future<Output = Result<Out, Err>>,
    U: IntoServiceFactory<T>, 

Service factory that prodices apply_fn service.