Usefulness of subclassing builtin number types

[Martin v. Löwis]

> Couldn't the builtin types's methods use 
> 
>     self.__class__(...)
> 
> to construct new objects?  

As I've said in <atiev5$sfe$07$1 at news.t-online.com>: No, unless 
someone resolves all semantic issues with such an approach.

Regards,
Martin