[Python-3000] Implementations: A syntax for extending method dispatching beyond type/class inheritance

[Bill Janssen]

Hi, Dave.

> Implementations are used to make Method Dispatching more flexible by 
> allowing a class to claim that it acts like another class/type even 
> though it is not derived from that class/type.

I'm not sure just what this adds over the simple "change_class"
function that I've posted twice already.  Is there an implementation
efficiency argument here?

What happens when you call an existing method from one of the
(supertypes?) of an implementation?  Do you have to re-implement it?
Or do you have some way of coercing the value to that type?      

Bill