tmp2  = big.NewInt(0)
	numer = big.NewInt(1)
	accum = big.NewInt(0)
	denom = big.NewInt(1)
	ten   = big.NewInt(10)
)

func extractDigit() int64 {
	if big.CmpInt(numer, accum) > 0 {
		return -1
	}
	tmp1.Lsh(numer, 1).Add(tmp1, numer).Add(tmp1, accum)
	big.DivModInt(tmp1, tmp2, tmp1, denom)
	tmp2.Add(tmp2, numer)
	if big.CmpInt(tmp2, denom) >= 0 {
		return -1
	}
	return tmp1.Int64()
}

pkg go/constant, func BitLen(Value) int
pkg go/constant, func BoolVal(Value) bool
pkg go/constant, func Bytes(Value) []uint8
pkg go/constant, func Compare(Value, token.Token, Value) bool
pkg go/constant, func Denom(Value) Value
pkg go/constant, func Float32Val(Value) (float32, bool)
pkg go/constant, func Float64Val(Value) (float64, bool)
pkg go/constant, func Imag(Value) Value
pkg go/constant, func Int64Val(Value) (int64, bool)

pkg math/big, method (*Int) Xor(*Int, *Int) *Int
pkg math/big, method (*Rat) Abs(*Rat) *Rat
pkg math/big, method (*Rat) Add(*Rat, *Rat) *Rat
pkg math/big, method (*Rat) Cmp(*Rat) int
pkg math/big, method (*Rat) Denom() *Int
pkg math/big, method (*Rat) FloatString(int) string
pkg math/big, method (*Rat) GobDecode([]uint8) error
pkg math/big, method (*Rat) GobEncode() ([]uint8, error)
pkg math/big, method (*Rat) Inv(*Rat) *Rat