Function fn_service

pub fn fn_service<F, Fut, Req, Res, Err, Cfg>(
    f: F,
) -> FnServiceFactory<F, Fut, Req, Res, Err, Cfg>
where
    F: Fn(Req) -> Fut + Clone,
    Fut: Future<Output = Result<Res, Err>>,

Create ServiceFactory for function that can act as a Service