Add 'if __name__ == "__main__":' to files already as a usable as a module.
diff --git a/Demo/scripts/primes.py b/Demo/scripts/primes.py
index 00eb05f..5935a3c 100755
--- a/Demo/scripts/primes.py
+++ b/Demo/scripts/primes.py
@@ -23,4 +23,5 @@
             if i >= min: print i
         i = i+2
 
-main()
+if __name__ == "__main__":
+    main()