normalize shebang lines to #!/usr/bin/env python
diff --git a/Demo/turtle/tdemo_bytedesign.py b/Demo/turtle/tdemo_bytedesign.py
index 6f53e9f..bed671d 100644
--- a/Demo/turtle/tdemo_bytedesign.py
+++ b/Demo/turtle/tdemo_bytedesign.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 """      turtle-example-suite:
 
         tdemo_bytedesign.py