die unless ( $answer eq 'Y' or 'y' );

##</code><code>##

die unless (  ($answer eq 'Y') or ('y')  );

##</code><code>##

$ perl -MO=Deparse,-p -e  'die unless ( $answer eq "Y" or  "y");'
((($answer eq 'Y') or 'y') or die);
-e syntax OK

##</code><code>##

> my $answer = "y";
y
> say "true" if $answer eq 'Y' | 'y';
true
> say "true" if $answer eq 'N' | 'y';
true
> say "true" if $answer eq 'N' | 'n';
Nil
>