#!/usr/local/bin/perl -l

use strict;

foreach (0,'',undef) {
   print "'$_' is zero number" if $_ == 0;
   print "'$_' is zero string" if $_ eq '0';
   print "'$_' is empty string" if $_ =~ /^$/;
   print "'$_' is empty string" if $_ eq '';
   print "'$_' is undef" if ! defined $_;
}
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jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)