use strict;
use warnings;

use Data::Dumper;

my @arrA = ( [0, 1, 2] );
unshift @arrA, 1;

print Data::Dumper->Dump([\@arrA], [q{*arrA}]);

shift @arrA;
unshift @arrA, [1];

print Data::Dumper->Dump([\@arrA], [q{*arrA}]);

##</code><code>##

@arrA = (
          1,
          [
            0,
            1,
            2
          ]
        );
@arrA = (
          [
            1
          ],
          [
            0,
            1,
            2
          ]
        );