$ perl -MDevel::Peek -e'my $x = 123; Dump($x); $x = "abc"; Dump($x);'
SV = IV(0x2764760) at 0x2764770
  REFCNT = 1
  FLAGS = (IOK,pIOK)
  IV = 123
SV = PVIV(0x2766c38) at 0x2764770
  REFCNT = 1
  FLAGS = (POK,IsCOW,pPOK)
  IV = 123
  PV = 0x27c1258 "abc"\0
  CUR = 3
  LEN = 10
  COW_REFCNT = 1