use jester with SSE (server side event) example

[me7]

Right now web socket library (treeform/ws) not working with httpBeast on jester 
yet 
[https://github.com/treeform/ws/issues/11#event-2831261507](https://github.com/treeform/ws/issues/11#event-2831261507).
 So I want to use SSE (server side event) instead.

After googling and do it myself several time I still cannot make it work yet. 
Anyone could here guide me what's the correct way to use it with jester? (I'll 
do pull request to jester to add this example after it work)

Here's code that working ok but using PHP 
[https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events](https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events)

Here's my code so far (that's not work)

server 
    
    
    import jester
    import os, random
    
    routes:
      get "/":
        resp "Home"
      get "/demo_sse":
        request.headers.add "Content-Type", "text/event-stream"
        request.headers.add "Cache-Control", "no-cache"
        request.sendHeaders()
        for i in 1..20:
          request.send($rand(100))
          sleep(100)
    
    
    Run

client code in js
    
    
            var source = new EventSource("/demo_sse");
            source.onmessage = function (event) {
                document.getElementById("result").innerHTML += event.data + 
"<br>";
            };
    
    
    Run

Any example available?