Python has recently seen a number of experiments to improve its parallel performance, including exposing subinterpreters as part of the standard library. These allow separate threads within the same ...

Here, although there's no "is-a" relationship between Square and Rectangle, there exists such thing between SquareR and RectR, SquareW and RectW. That is: SquareR is a RectR (this is natural) RectW is ...