Fixed code in 'Event Hooks' section

diff --git a/docs/user/advanced.rst b/docs/user/advanced.rst
index d1c2cd0c79297afd041848624541f98427c51c0e..1ffd778d739ae60f378ba52b52bc7f5d1601f99b 100644 (file)
--- a/docs/user/advanced.rst
+++ b/docs/user/advanced.rst
@@ -194,7 +194,7 @@ Let's print some request method arguments at runtime::
 Let's hijack some arguments this time with a new callback::
 
     def hack_headers(args):
-        if not args[headers]:
+        if args.get('headers') is None:
             args['headers'] = dict()
 
         args['headers'].update({'X-Testing': 'True'})