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

[Ben Finney]

Mark, you are demonstrating a habit of making sweeping pronouncements
and assertions; and then, when those statements are challenged, you
act as though you never said them.

Here's a characteristic example:

Mark H Harris <harrismh777 at gmail.com> writes:

> On 3/30/14 10:22 AM, Steven D'Aprano wrote:
> > Mark H Harris <harrismh777 at gmail.com> writes:
> >> I didn't really start using unicode until about 5 years ago; python
> >> has only really used it since python3. right?
> >
> > No. Python 2.2 introduced Unicode.
>
> I didn't ask when it was introduced, I asked when it became useful?

That's clearly not what you asked, in the material you quoted above; and
Steven's answer to your actual false assertion is entirely appropriate.

There are many other examples in this thread, but I'm not seeking to
catalogue them; merely to show an example of what I'm observing.

I hope you can see that this behaviour quickly leads many people to
quite reasonably disregard your assertions in general, and even to
ignore you altogether. Do you think you can tone down the rhetoric and
perhaps stand by the statements you actually make?

-- 
 \     “Injustice is relatively easy to bear; what stings is justice.” |
  `\                                                 —Henry L. Mencken |
_o__)                                                                  |
Ben Finney