--- my   @a before ---
$VAR1 = [
          'a',
          'b',
          'c',
          'd'
        ];
--- my   @a after ---
$VAR1 = [
          'a',
          'b',
          undef,
          'd'
        ];
--- my   %a before ---
$VAR1 = {};
--- my   %a after ---
$VAR1 = {
          'c' => undef,
          'a' => undef,
          'b' => undef,
          'd' => undef
        };