Save a struct with ID

[skynet0590]

For example. I have a struct

User struct {
 ID int
 Name string
}

When I insert a new User with no zero ID and higher with the last ID of User. The bucket still be no update the last ID. This make error when I create more User with zero ID. The user will fill up and when it reach the User was created by no zero ID. A new User will replace the old.