[
   11,
   22, # optional
   [
     [
      1
     ],
     [  #
      -1 # only here if 2 above is there
     ]  #
   ]
]

##</code><code>##

use Test::More tests => 2;
use Test::Deep;

my $id_re = re('^\d+$');
my $vpt_re = re('^-?1$');

my $x = [
          '11',
          '22',
          [
            [
              '-1',
            ],
            [                   # 
              '1',              # only present if '22' above present
            ]                   # 
          ]
        ];

my $y = [
          '11',
          [
            [
              '-1',
            ],
          ]
        ];

my $comp =
    [
        $id_re,
        $id_re,
        subbagof([$vpt_re], [$vpt_re])
    ];

cmp_deeply($x, $comp, 'test1');
cmp_deeply($y, $comp, 'test2');