$ perl -MDevel::Peek -e'
   sub f {
      my $x;
      Dump($x);
      my @a = map { sub { $x } } 1..3;
      Dump($x);
   }
   f()
'
SV = NULL(0x0) at 0x817bc90
  REFCNT = 1
  FLAGS = (PADMY)
SV = NULL(0x0) at 0x817bc90
  REFCNT = 4
  FLAGS = (PADMY)