From 5c2b39b26bddcd7f0b9a75db260b7ba268153e25 Mon Sep 17 00:00:00 2001
From: Philipp Rudiger <P.Rudiger@ed.ac.uk>
Date: Fri, 1 Jul 2016 12:43:10 +0100
Subject: [PATCH] Ensured callbacks are robust to missing underscore.js

---
 holoviews/plotting/bokeh/callbacks.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/holoviews/plotting/bokeh/callbacks.py b/holoviews/plotting/bokeh/callbacks.py
index 9c528f2095..46e4325855 100644
--- a/holoviews/plotting/bokeh/callbacks.py
+++ b/holoviews/plotting/bokeh/callbacks.py
@@ -105,7 +105,7 @@ class Callback(param.ParameterizedFunction):
         }}
 
         timeout = HoloViewsWidget._timeout + {timeout};
-        if (_.isEmpty(data)) {{
+        if ((typeof _ === "undefined")  || _.isEmpty(data)) {{
         }} else if ((HoloViewsWidget._blocked && (Date.now() < timeout))) {{
             HoloViewsWidget._queued = [data];
         }} else {{