perl -MDevel::Peek -e 'Dump(!!0)'
SV = PVNV(0x1838140) at 0x18363f8
  REFCNT = 2147483647
  FLAGS = (IOK,NOK,POK,IsCOW,READONLY,PROTECT,pIOK,pNOK,pPOK)
  IV = 0
  NV = 0
  PV = 0x5e6583 "" [BOOL PL_No]
  CUR = 0
  LEN = 0