convert shebang lines: python -> python3
diff --git a/Demo/sockets/throughput.py b/Demo/sockets/throughput.py
index 64244aa..5954316 100755
--- a/Demo/sockets/throughput.py
+++ b/Demo/sockets/throughput.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/env python3
 
 # Test network throughput.
 #