  console.debug("Bokeh: BokehJS is being loaded, scheduling callback at", now());
      return null;
    }
    if (js_urls == null || js_urls.length === 0) {
      run_callbacks();
      return null;
    }
    console.debug("Bokeh: BokehJS not loaded, scheduling load and callback at", now());
    root._bokeh_is_loading = css_urls.length + js_urls.length;

    function on_load() {
      root._bokeh_is_loading--;
      if (root._bokeh_is_loading === 0) {
        console.debug("Bokeh: all BokehJS libraries/sty