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/demohelp.txt b/Demo/turtle/demohelp.txt
index d364e94..7d13763 100644
--- a/Demo/turtle/demohelp.txt
+++ b/Demo/turtle/demohelp.txt
@@ -52,6 +52,9 @@
(2) How to add your own demos to the demo repository
+ IMPORTANT! When imported, the demo should not modify the system
+ by calling functions in other modules, such as sys, tkinter, or
+ turtle. Global variables should be initialized in main().
- The script name must begin with tdemo_ ,
so it must have the form tdemo_<your-script-name>.py