Noting also the comment about it being a toggle, the ++ doesn't make sense to me either. But in that case, I would tend to wonder if the following is what is really meant: 
$| = !$|;

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Which is a good enough reason otherwise to support the above idea of just assigning one to it to avoid confusion.

One world, one people

In reply to Re: what does $|++ do here? by anonymized user 468275
in thread what does $|++ do here? by deep3101

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