Value: Avoid modifying s_null
Don't create a Private::null() in the ctors that shall not be a null value. If you happen to own the s_null, it will be modified and thus it is no more a null value.
Don't create a Private::null() in the ctors that shall not be a null value. If you happen to own the s_null, it will be modified and thus it is no more a null value.