How to create a limited set of instanceses of a class

[madpython]

Thanks, Alex, again. The lesson has been taught. I appreciate very much
you spent time trying to help. Indeed the culprit of that infrequent
infinite loops was that bound reference "item" in the printing
loop. But frankly i thought that it only existed inside that loop.
Apparently I was wrong and glad that it was revealed.
I guess unless there is something  to add here the problem is solved
and subject is closed. Thanks everyone who took their time to ponder on
it. I hope it was as much educational for you as it was for me.