Issue #21882: In turtle demos, remove module scope gui and sys calls by
moving them to the module's main function.
diff --git a/Demo/turtle/tdemo_clock.py b/Demo/turtle/tdemo_clock.py
index d4e0686..1d6eb80 100755
--- a/Demo/turtle/tdemo_clock.py
+++ b/Demo/turtle/tdemo_clock.py
@@ -11,11 +11,8 @@
   ------------------------------------
 """
 from turtle import *
-from turtle import Terminator  # not in __all__
 from datetime import datetime
 
-mode("logo")
-
 def jump(distanz, winkel=0):
     penup()
     right(winkel)
@@ -43,7 +40,6 @@
     hand_form = get_poly()
     register_shape(name, hand_form)
 
-
 def clockface(radius):
     reset()
     pensize(7)
@@ -84,7 +80,6 @@
     writer.pu()
     writer.bk(85)
 
-
 def wochentag(t):
     wochentag = ["Monday", "Tuesday", "Wednesday",
         "Thursday", "Friday", "Saturday", "Sunday"]
@@ -131,6 +126,7 @@
     return "EVENTLOOP"
 
 if __name__ == "__main__":
+    mode("logo")
     msg = main()
     print msg
-    mainloop()
+    mainloop()  # keep window open