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

[Chris Angelico]

On Sat, Mar 29, 2014 at 8:18 AM, Mark H Harris <harrismh777 at gmail.com> wrote:
> We have a unicode system [1] capable of zillions of characters, and most of
> [us] have some qwerty system keyboard [104 keys?] with meta key mappings for
> a few more. Talk about the cart before the horse.
>
> We need a standard input system not controlled by Microsoft...

... uhh... how does the QWERTY system demonstrate Microsoft's
control?? There's more than a hundred years of gap between them, and
in the wrong order.

By the way, thanks for telling me what a zillion is. It must be 65536,
because that's the biggest thing Unicode gives us plural of in number
of characters. :)

Considering that we have ten fingers, having 1114112 keys would be
quite impractical. The smallest number of keys to render that many
characters would probably be 21, but it'd be toggling data into a
computer, rather than typing; *every* character would require holding
down a good number of keys. (Or you could go the other way and have
exactly two keys: 1 and 0. Press either 21 times to enter a single
character.) You'd probably need a minimum of several hundred keys to
get something reasonably logical.

Do you really want a keyboard that takes up that much space? Most
people can't efficiently use F1 through F12, much less another hundred
or two hundred keys.

ChrisA