$ perl -MDevel::Peek -we '$a = undef; $b = undef; Dump($a); Dump($b)'
SV = NULL(0x0) at 0x8191dc4
  REFCNT = 1
  FLAGS = ()
SV = NULL(0x0) at 0x8191ddc
  REFCNT = 1
  FLAGS = ()

##</code><code>##

$ perl -MDevel::Peek -we '$a = 1; $b = 2; Dump ($a); Dump ($b)'
SV = IV(0x8192edc) at 0x8191dbc
  REFCNT = 1
  FLAGS = (IOK,pIOK)
  IV = 1
SV = IV(0x8192ee4) at 0x8191de0
  REFCNT = 1
  FLAGS = (IOK,pIOK)
  IV = 2