use Devel::Peek qw(SvREFCNT);

my $a = 9;                   # 1 = $a is an SV of an IV with refcnt of
+ 1
warn SvREFCNT($a), "\n";

my $b = \$a;                 # 2 = (anonymous) scalar ref maintained b
+y $b
warn SvREFCNT($a), "\n";

my $d = my $c = $b;          # 4 = two more ref copies made
warn SvREFCNT($a), "\n";

my $f = my $e = \$b;         # 4 = $a unaffected by references _to_ $b
warn SvREFCNT($a), "\n";

my $g = [ $a ];              # 4 = copy of value  $a in array
warn SvREFCNT($a), "\n";

my $h = [ $c ];              # 5 = copy of ref to $a in array
warn SvREFCNT($a), "\n";

my $i = sub { $b, $c, $e };  # 5 = $a unaffected by closure over _refs
+_ to $a
warn SvREFCNT($a), "\n";

my $j = sub { $a, $a, $a };  # 6 = closure over actual lexical $a
warn SvREFCNT($a), "\n";

undef $_ for $b, $c, $d, $h, $j;  # 1 = kill all refcnt contributors (
+except for $a itelf)
warn SvREFCNT($a), "\n";
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