convert shebang lines: python -> python3
diff --git a/Demo/comparisons/systemtest.py b/Demo/comparisons/systemtest.py
index e3d840e..8276333 100755
--- a/Demo/comparisons/systemtest.py
+++ b/Demo/comparisons/systemtest.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/env python3
 
 # 3)  System Test
 #