#!/usr/bin/perl --
use strict;
use warnings;
use Data::Dumper;
my( @cluster_60 ) = (
  { 3 => 4 },
  { 2 => 8 },
  {},
  {},
  { 1 => 5 },
);

$cluster_60[2]{hot} = 'dog';
print Dumper( \@cluster_60);
__END__
$VAR1 = [
          {
            '3' => 4
          },
          {
            '2' => 8
          },
          {
            'hot' => 'dog'
          },
          {},
          {
            '1' => 5
          }
        ];