Function handle_rend_requests 

pub fn handle_rend_requests<S>(
    rend_requests: S,
) -> impl Stream<Item = StreamRequest>
where
    S: Stream<Item = RendRequest>,

Consume a stream of RendRequest, accepting them all, and produce a stream of StreamRequest.

If you want to reject certain RendRequests, you can use StreamExt::filter or similar in order to remove them from the incoming stream.