use Devel::Peek;

my $scalar;
Dump($scalar);
Dump(undef);
Dump(5);
Dump('abc');

# SV = NULL(0x0) at 0x250b98c
  # REFCNT = 1
  # FLAGS = (PADMY)
# SV = NULL(0x0) at 0x9f3788
  # REFCNT = 2147480012
  # FLAGS = (READONLY)
# SV = IV(0x250b998) at 0x250b99c
  # REFCNT = 1
  # FLAGS = (PADTMP,IOK,READONLY,pIOK)
  # IV = 5
# SV = PV(0x261b534) at 0x25021b4
  # REFCNT = 1
  # FLAGS = (PADTMP,POK,READONLY,pPOK)
  # PV = 0x2716f54 "abc"\0
  # CUR = 3
  # LEN = 4