convert shebang lines: python -> python3
diff --git a/Demo/sockets/telnet.py b/Demo/sockets/telnet.py
index 038036ff..fb36faf 100755
--- a/Demo/sockets/telnet.py
+++ b/Demo/sockets/telnet.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/env python3
 
 # Minimal interface to the Internet telnet protocol.
 #