wsgi: Update docstring example for python 3

Fixes #2960

diff --git a/tornado/wsgi.py b/tornado/wsgi.py
index 825b395cf5bb21abd0d62f68af62cd92dc213ca0..55ece9a22b98b77bf3d158d12ca36a818fb21ce2 100644 (file)
--- a/tornado/wsgi.py
+++ b/tornado/wsgi.py
@@ -73,7 +73,7 @@ class WSGIContainer(object):
             status = "200 OK"
             response_headers = [("Content-type", "text/plain")]
             start_response(status, response_headers)
-            return ["Hello world!\n"]
+            return [b"Hello world!\n"]
 
         container = tornado.wsgi.WSGIContainer(simple_app)
         http_server = tornado.httpserver.HTTPServer(container)