This is the revision history for $b in <freenode.net:##perl>

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10443 $b is [fact $a]
Don't use $a or $b as variable names. Not even in examples. They are not normal variables and will not behave like normal variables. The only place they are cromulent is in a sort or List::Util block. Please see https://metacpan.org/pod/Perl::Critic::Policy::Community::DollarAB ; consider using $x, $y instead. | https://perldoc.perl.org/variables/$a
pink_mist <*:##NULL>