[Python-ideas] Add lookahead iterator (peeker) to itertools

[Masklinn]

On 2013-02-25, at 13:37 , Joao S. O. Bueno wrote:

> Hi all!
> 
> What is the problem with iterttols.tee even?
> It is almots the samething - although much more flexible, than what is
> proposed on this thread.
> 
> 
>>>> from itertools import tee
>>>> my_iter, peek = tee(iter(range(3)), 2)
>>>> next(peek)
> 0
>>>> next(my_iter)
> 0
>>>> 

Verbose way to do the same thing: you have to tee() + next() once per
"peek()". And splitting to subroutines means these subroutines will have
to return an iterator alongside any potential value as they'll have to
tee() themselves.