exp/cpp/export/uuid.go
func (s *Xor64Source) next() uint64 {
	x := xor64(uint64(*s))
	*s = Xor64Source(x)
	return x
}
func (s *Xor64Source) next() uint64 {
	x := xor64(uint64(*s))
	*s = Xor64Source(x)
	return x
}
// next advances the generators internal state to the next value and returns
// this value as an uint64.