It flip-flops like a switch when you increment it.

If only.

It's worse. It acts like a flip-flop when you decrement it, but not when you increment.

perl -wE 'say $|++ for 1 .. 5; say "--"; say $|-- for 1 .. 5' 
0
1
1
1
1
--
1
0
1
0
1
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