normalize shebang lines to #!/usr/bin/env python
diff --git a/Demo/turtle/tdemo_peace.py b/Demo/turtle/tdemo_peace.py
index ea57069..13044c9 100644
--- a/Demo/turtle/tdemo_peace.py
+++ b/Demo/turtle/tdemo_peace.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 """       turtle-example-suite:
 
               tdemo_peace.py