How to use the rx-jupyter.contents.update function in rx-jupyter

payload: { error: new Error("updating content needs a payload") }
        }) as any;
      }

      const state: any = state$.value;
      const host: any = selectors.currentHost(state);

      // Dismiss any usage that isn't targeting a jupyter server
      if (host.type !== "jupyter") {
        return empty();
      }

      const { contentRef, filepath, prevFilePath } = action.payload;
      const serverConfig: ServerConfig = selectors.serverConfig(host);

      return contents
        .update(serverConfig, prevFilePath, { path: filepath.slice(1) })
        .pipe(
          tap(xhr => {
            if (xhr.status !== 200) {
              throw new Error(xhr.response);
            }
          }),
          map(() => {
            /*
             * Modifying the url's file name in the browser.
             * This effects back button behavior.
             * Is there a better way to accomplish this?
             */
            window.history.replaceState(
              {},
              filepath,