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

[Ian Kelly]

On Mon, Mar 24, 2014 at 12:58 PM, Mark H Harris <harrismh777 at gmail.com> wrote:
> That is what we mean by confusing. Or another really great example is this
> thread. Somebody asks about a language feature and somebody else helpfully
> answers the question by providing them with a similar lambda!!

That is not in fact how the topic of lambda arose in this thread.
Rustom Mody brought up the binding behavior in a tangent specifically
to complain about it, and that was the first mention of lambda in the
thread.