The power of the do block

do_block.pl

#!/usr/bin/perl
use strict;
use warnings;

my $n = shift;

#my $desc;
#if ( $n > 0 ) {
#    $desc = 'positive';
#} elsif ( $n < 0 ) {
#    $desc = 'negative';
#} else {
#    $desc = 'zero';
#}
my $desc = do {
    if    ( $n > 0 ) { 'positive'; }
    elsif ( $n < 0 ) { 'negative'; }
    else             { 'zero'; }
};

print "$n is $desc\n";