convert shebang lines: python -> python3
diff --git a/Demo/scripts/from.py b/Demo/scripts/from.py
index 323e684..c8a9346 100755
--- a/Demo/scripts/from.py
+++ b/Demo/scripts/from.py
@@ -1,4 +1,4 @@
-#! /usr/bin/env python
+#! /usr/bin/env python3
 
 # Print From and Subject of messages in $MAIL.
 # Extension to multiple mailboxes and other bells & whistles are left