--- a/doc/_static/listings/tutorial3-netstrings2.py	2015-09-09 10:37:48.000000000 +0800
+++ b/doc/_static/listings/tutorial3-netstrings2.py	2020-09-27 18:54:46.607308297 +0800
@@ -21,7 +21,7 @@
         self.transport = transport
 
     def sendNetstring(self, string):
-        print 'received', repr(string)
+        print('received'), repr(string)
 
 
 class NetstringReceiver(object):