Explanation of this Python language feature? [x for x in x for x in x] (to flatten a nested list)

[Mark H Harris]

On 4/4/14 3:20 AM, Mark Lawrence wrote:
> On 04/04/2014 03:29, Mark H Harris wrote:
>>
>>     Now, about Python2.  It has not died.  It appears to be 'useful'.
>> {snip}
>>
>
> For a lot of people, if it ain't broke, don't fix it.
>

hi Mark, yes that's my point. I have heard rumors of python2.8? At some 
point I would expect that the Cpython interpreter would 'freeze' and no 
one would fix it any longer. I have a serious question, namely, why does 
the Cpython community continue to suppport two interpreters rather than 
asking the Cpython user-base to migrate to Cpython3?

Oh, I have another serious question about implementations. I'm not sure 
about (50) implementations, but I know that Jython and IronPython are 
serious contenders (although, I have not, nor probably will, use them).

Are the other implementation communities *also* supporting two versions 
of the language?   Is there a Jython2 &also a Jython3 ?

marcus