Repair example code in doc string.

Bug fix candiadte.
diff --git a/Demo/metaclasses/Eiffel.py b/Demo/metaclasses/Eiffel.py
index d9c8a9a..68eb1cd 100644
--- a/Demo/metaclasses/Eiffel.py
+++ b/Demo/metaclasses/Eiffel.py
@@ -28,7 +28,7 @@
 
 class D(C):
     def m1(self, arg):
-        return whatever**2
+        return arg**2
     def m1_post(self, Result, arg):
         C.m1_post(self, Result, arg)
         assert Result < 100