Not x.islower() has different output than x.isupper() in list output...

[Chris Angelico]

On Tue, May 3, 2016 at 9:25 PM, Jussi Piitulainen
<jussi.piitulainen at helsinki.fi> wrote:
> Chris Angelico writes:
>
>> This assumes, of course, that there is a function swapcase which can
>> return a string with case inverted. I'm not sure such a function
>> exists.
>
>    str.swapcase("foO")
>    'FOo'

I suppose for this discussion it doesn't matter if it's imperfect.

>>> "\N{ANGSTROM SIGN}".swapcase().swapcase() == "\N{ANGSTROM SIGN}"
False
>>> "\N{LATIN SMALL LETTER SHARP S}".swapcase().swapcase()
'ss'

But drawing the analogy with the negation of real numbers implies
something that doesn't exist.

ChrisA