use re 'eval';
$a='12345678910-=[];\'#/.,\\-!\"\u00A3$%^&*()_+{}~@:<>?| \u2013';
$a=~ s/((\\u....)|(.))(?{ if (defined $2){'y'} elsif(defined $3) {'x'}
+ else{$1} })/$^R/xg;
print $a;
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prints :
xxxxxxxxxxxxxxxxxxxxxxxxxxyxxxxxxxxxxxxxxxxxxxy