Repair flawed example.
diff --git a/Lib/test/test_generators.py b/Lib/test/test_generators.py
index a5b2c37..5bad79a 100644
--- a/Lib/test/test_generators.py
+++ b/Lib/test/test_generators.py
@@ -47,7 +47,7 @@
 
     >>> def f():
     ...     yield 1
-    ...     return
+    ...     raise StopIteration
     ...     yield 2 # never reached
     ...
     >>> g = f()