List as FIFO in for loop

[castironpi at gmail.com]

> Notice that the language specification *deliberately* does not
> distinguish between deletion of earlier and later items, but
> makes modification of the sequence undefined behavior to allow
> alternative implementations. E.g. an implementation that would
> crash, erase your hard disk, or set your house in flames if you
> confront it with your code still might be a conforming Python
> implementation.

Actually, PEP 4122 makes this a SetHouseInFlames error.  Do you want
to include this one?  Just use _toaddafter= type( container )().

P.S.  Equivalence class light, on the rocks.