Added Q&A about "return".

pep-0255.txt

@@ -310,6 +310,24 @@ Q & A
        determine potential suspension points at compile-time, and a new
        keyword makes that easy.
 
+    Q. Why allow "return" at all?  Why not force termination to be spelled
+       "raise StopIteration"?
+
+    A. The mechanics of StopIteration are low-level details, much like the
+       mechanics of IndexError in Python 2.1:  the implementation needs to
+       do *something* well-defined under the covers, and Python exposes
+       these mechanisms for advanced users.  That's not an argument for
+       forcing everyone to work at that level, though.  "return" means "I'm
+       done" in any kind of function, and that's easy to explain and to use.
+
+    Q. Then why not allow an expression on "return" too?
+
+    A. Perhaps we will someday.  In Icon, "return expr" means both "I'm
+       done", and "but I have one final useful value to return too, and
+       this is it".  At the start, and in the absence of compelling uses
+       for "return expr", it's simply cleaner to use "yield" exclusively
+       for delivering values.
+
 
 Reference Implementation