C:\> perl -MDevel::Peek -e"Dump { }
SV = RV(0x183cfc8) at 0x226074
  REFCNT = 1
  FLAGS = (TEMP,ROK)
  RV = 0x225f84
  SV = PVHV(0x22b504) at 0x225f84
    REFCNT = 1
    FLAGS = (SHAREKEYS)
    IV = 0         <<<------------------------------------------
    NV = 0
    ARRAY = 0x0
    KEYS = 0       <<<------------------------------------------
    FILL = 0
    MAX = 7
    RITER = -1
    EITER = 0x0

C:\>perl -MDevel::Peek -e"Dump { 1..10 }
SV = RV(0x183cfc8) at 0x182f4f4
  REFCNT = 1
  FLAGS = (TEMP,ROK)
  RV = 0x225f94
  SV = PVHV(0x22b514) at 0x225f94
    REFCNT = 1
    FLAGS = (SHAREKEYS)
    IV = 5         <<<------------------------------------------
    NV = 0
    ARRAY = 0x1825554  (0:3, 1:5)
    hash quality = 150.0%
    KEYS = 5       <<<------------------------------------------
    FILL = 5
    MAX = 7
    RITER = -1
    EITER = 0x0
    Elt "1" HASH = 0x806b80c9
    SV = IV(0x1828ce0) at 0x226084
      REFCNT = 1
      FLAGS = (IOK,pIOK)
      IV = 2
    Elt "3" HASH = 0xa400c7f3
    SV = IV(0x1828d04) at 0x2260b4
      REFCNT = 1
      FLAGS = (IOK,pIOK)
      IV = 4
    Elt "7" HASH = 0xecc9d984
    SV = IV(0x1828d14) at 0x2260f0
      REFCNT = 1
      FLAGS = (IOK,pIOK)
      IV = 8