Sorted Returns List and Reversed Returns Iterator

[Fredrik Lundh]

John Machin wrote:

> reversed came later; returning an iterator rather than a list provides
> more flexibility.

As in flexibility for the implementer, the day someone invents a sort 
algorithm that doesn't have to look at all source items before it starts 
producing output?

Because I fail to see how returning an object that supports forward 
iteration only is more flexible for the *user* than returning an object 
that supports random access, mutation, restartable iteration, *and* 
forward iteration.

</F>