This is the revision history for $a xor $b in <>

10446 $a xor $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 ; consider using $x, $y instead. |$a
pink_mist <*:##NULL>