Recursive list comprehension

[Steven Bethard]

Terry Reedy wrote:
> This is a ways off, if ever, but I think the general advice for user code 
> is to use the newer protocol.

Yes, definitely.  I hope no one misconstrued me to be suggesting that 
you should use the 'sequence protocol' for iterators (e.g. using 
__getitem__ and raising an IndexError).  This is deprecated and is only 
supported for backwards compatiblity.  All new code should define 
__iter__ instead.

> So, for the purpose of writing new code, I 
> think it justified to forget about or at least ignore the older iteration 
> protocol.

This is probably valid as long as you don't need your code to work with 
any objects defined before the __iter__ protocol.

Steve