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

[MRAB]

On 2014-03-30 23:57, Rhodri James wrote:
> On Sun, 30 Mar 2014 11:44:13 +0100, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>
>> On Sun, 30 Mar 2014 00:32:58 -0700, Larry Hudson wrote:
>>
>>> Unfortunately, there is no good word for "USA-ian".  "United States
>>> Citizen" is too long and awkward and "United Statesian" is ridiculous.
>>> The common usage of "American" for this is at best ambiguous, and
>>> definitely inaccurate (as well as chauvinistic, and rather insulting to
>>> other North and South Americans outside the US).
>>
>> Among fans of the British writer Terry Pratchett, the usual term is
>> Merkins. Including among Merkin fans.
>
> Many of whom even know what a merkin is, and use the term anyway.
>
Isn't that what some said it sounded like when George W Bush said it?

"My fellow 'mercns, ..."