[Python-3000] Abilities / Interfaces

[Bill Janssen]

> I'm asking for a committee to lay this to rest by defining the one
> true hierarchy for containers. Other languages have succeeded in doing
> so (even Java).

Well, I don't think Java has really done this yet.  But it's a good
idea.  Someone should try to re-describe the standard set of Python
built-in types (list, tuple, file, string, dict, etc.) as a set of
ABCs (not sure they have to be all that abstract, either), using
inheritance to describe abilities.  If it can't be done, that would be
a strike against ABC, I'd think :-).

Bill