my @level1 = (
   [1, 2, 3, 4, 5],
   [6, 7, 8, 9, 10]
);

##</code><code>##

for (my $i = 0; $i < @level1; $i++) {
     for (my $j = 0; $j < @{$level1[$i]}; $j++) {
          print STDOUT "\$i: " . $i . " \$j: " . $j . " value: " . $level1[$i][$j] . "\n";
     }
}

##</code><code>##

my @level1 = (
	[ 1, 2, 3, [4, 5] ],
	6,
	7,
	[ 8, [9, [10] ] ],
);

&read_array(\@level1);

exit 0;

sub read_array {
    my $array_reference = shift;

    foreach (@$array_reference) {
        if (ref($_) eq 'ARRAY') {
            &read_array($_);
        } else {
            print $_ . "\n";
        }
    }
}