use strict;
use warnings;
use feature 'say';
use Devel::Peek;
use Storable qw/ freeze thaw /;

my $s = 'abc';
my $r = \substr $s, 1, 1;

say ref $r;                 # LVALUE
Dump $r;                    #
say ${ thaw freeze $r };    # failure

$$r = 'Z';

say ref $r;                 # LVALUE again
Dump $r;                    # ref target is now POK, PV is "Z"
say ${ thaw freeze $r };    # "Z"


##</code><code>##

use strict;
use warnings;
use feature 'say', 'state';
use Devel::Peek;
use Storable qw/ freeze thaw /;

sub foo : lvalue { state $r; $$r }
foo = 42;

say ref \foo;               # SCALAR
Dump \foo;                  # Nothing interesting. Much 
                            # shorter output than one 
                            # full of magic, above.
say ${ thaw freeze \foo };  # 42


##</code><code>##

@result = mce_map { ...work with $_ } substr(...)
@result = mce_map { ...work with $$_ } \substr(...)
@result = mce_map { ...work with $$_ } \( my $s = substr(...))