async.clj

  ([handler {:keys [on-open on-close on-message on-error] :as callbacks}]
   (fn [request]
     (if (:websocket? request)
       {:status 200 :body (initialize-websocket request callbacks)}
       (if handler
         (handler request)
         {:status 200 :body (initialize-stream request callbacks)}))))
  ([callbacks]
   (as-channel nil callbacks))