convert shebang lines: python -> python3
diff --git a/Demo/pysvr/pysvr.py b/Demo/pysvr/pysvr.py
index 3e94dbe..578e99c 100755
--- a/Demo/pysvr/pysvr.py
+++ b/Demo/pysvr/pysvr.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/env python3
 
 """A multi-threaded telnet-like server that gives a Python prompt.