Preopenstack confusion

[Michael J. Lew]

Thanks for the responses to my query. I have used a combination of 
several of the suggestions: a global holding the has_been_cleaned 
flag (because it will automatically expire at the end of a session) 
and empty preOpenStack handlers in the substacks (because my father 
always liked belt-and-braces approaches).

Sorry for the double posting. I sent the first to a miss-typed 
address and didn't expect it to get there.

Regards
-- 
Michael J. Lew

Senior Lecturer
Department of Pharmacology
The University of Melbourne
Parkville 3010
Victoria
Australia

Phone +613 8344 8304

**
New email address: michaell at unimelb.edu.au
**