normalize shebang lines to #!/usr/bin/env python
diff --git a/Demo/turtle/tdemo_I_dontlike_tiltdemo.py b/Demo/turtle/tdemo_I_dontlike_tiltdemo.py
index adec52b..c9e6e65 100644
--- a/Demo/turtle/tdemo_I_dontlike_tiltdemo.py
+++ b/Demo/turtle/tdemo_I_dontlike_tiltdemo.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 """       turtle-example-suite:
 
      tdemo-I_dont_like_tiltdemo.py
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
diff --git a/Demo/turtle/tdemo_clock.py b/Demo/turtle/tdemo_clock.py
index 11c37f0..b6280bb 100644
--- a/Demo/turtle/tdemo_clock.py
+++ b/Demo/turtle/tdemo_clock.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # -*- coding: cp1252 -*-
 """       turtle-example-suite:
 
diff --git a/Demo/turtle/tdemo_fractalcurves.py b/Demo/turtle/tdemo_fractalcurves.py
index f34c5fc..2ac8ecd 100644
--- a/Demo/turtle/tdemo_fractalcurves.py
+++ b/Demo/turtle/tdemo_fractalcurves.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 """      turtle-example-suite:
 
         tdemo_fractalCurves.py
diff --git a/Demo/turtle/tdemo_lindenmayer_indian.py b/Demo/turtle/tdemo_lindenmayer_indian.py
index 4f20716..92c8cff 100644
--- a/Demo/turtle/tdemo_lindenmayer_indian.py
+++ b/Demo/turtle/tdemo_lindenmayer_indian.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 """       turtle-example-suite:
 
         xtx_lindenmayer_indian.py
diff --git a/Demo/turtle/tdemo_minimal_hanoi.py b/Demo/turtle/tdemo_minimal_hanoi.py
index 4e2ad48..8a1caa8 100644
--- a/Demo/turtle/tdemo_minimal_hanoi.py
+++ b/Demo/turtle/tdemo_minimal_hanoi.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 """       turtle-example-suite:
 
          tdemo_minimal_hanoi.py
diff --git a/Demo/turtle/tdemo_paint.py b/Demo/turtle/tdemo_paint.py
index 65741da..e1d6303 100644
--- a/Demo/turtle/tdemo_paint.py
+++ b/Demo/turtle/tdemo_paint.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 """       turtle-example-suite:
 
             tdemo_paint.py
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
diff --git a/Demo/turtle/tdemo_penrose.py b/Demo/turtle/tdemo_penrose.py
index 4d8a61e..f5824d7 100644
--- a/Demo/turtle/tdemo_penrose.py
+++ b/Demo/turtle/tdemo_penrose.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 """       xturtle-example-suite:
 
           xtx_kites_and_darts.py
diff --git a/Demo/turtle/tdemo_planet_and_moon.py b/Demo/turtle/tdemo_planet_and_moon.py
index e3c87a0..223d87b 100644
--- a/Demo/turtle/tdemo_planet_and_moon.py
+++ b/Demo/turtle/tdemo_planet_and_moon.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 """       turtle-example-suite:
 
         tdemo_planets_and_moon.py
diff --git a/Demo/turtle/tdemo_tree.py b/Demo/turtle/tdemo_tree.py
index 3c7178c..6fc8735 100644
--- a/Demo/turtle/tdemo_tree.py
+++ b/Demo/turtle/tdemo_tree.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 """      turtle-example-suite:
 
              tdemo_tree.py
diff --git a/Demo/turtle/tdemo_yinyang.py b/Demo/turtle/tdemo_yinyang.py
index 47b8b2f..04dd758 100644
--- a/Demo/turtle/tdemo_yinyang.py
+++ b/Demo/turtle/tdemo_yinyang.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 """       turtle-example-suite:
 
             tdemo_yinyang.py
diff --git a/Demo/turtle/turtleDemo.py b/Demo/turtle/turtleDemo.py
index 38a44e0..3030d91 100644
--- a/Demo/turtle/turtleDemo.py
+++ b/Demo/turtle/turtleDemo.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 import sys
 import os
 
diff --git a/Demo/turtle/turtledemo_two_canvases.py b/Demo/turtle/turtledemo_two_canvases.py
index 5cde0ef..5a9831d 100644
--- a/Demo/turtle/turtledemo_two_canvases.py
+++ b/Demo/turtle/turtledemo_two_canvases.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 ## DEMONSTRATES USE OF 2 CANVASES, SO CANNOT BE RUN IN DEMOVIEWER!
 """turtle example: Using TurtleScreen and RawTurtle
 for drawing on two distinct canvases.