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

[Dan Stromberg]

On Fri, Mar 21, 2014 at 1:42 PM, vasudevram <vasudevram at gmail.com> wrote:
> Can anyone - maybe one of the Python language core team, or someone with knowledge of the internals of Python - can explain why this code works, and whether the different occurrences of the name x in the expression, are in different scopes or not? :
>
> x = [[1,2], [3,4], [5,6]]
>     [x for x in x for x in x]

I'll give this +1 for playfulness, and -2 for lack of clarity.

I hope no one thinks this sort of thing is good to do in real-life code.