Variable inheritance

[Courageous]

>Can anyone provide an example where MI is used for right purpose,
>not just to quickly hack something?

Dynamic aggregation and the reuse of interface implementations
(ala "mixin based programming," first popularized in the Lisp
community, but then propagated about).

While this is an irrelevant ad hominem I'm about to state, questions
like your are generally posed by programmers from _static_ languages.
Python is a _dynamic_ language. This sometimes requires rethink.

C//