[Datetime-SIG] Computing .dst() as a timedelta

[Tim Peters]

[Alex]
> I wonder, what's the point of saving daylight at the place where sun does
> not set? (or does not rise depending on the time of the year?)

What's the point of DST _anywhere_?  Politics :-)  But in Antarctica,
the base notion of "time zone" itself is essentially senseless:

https://en.wikipedia.org/wiki/Time_in_Antarctica

"""
Antarctica sits on every line of longitude, due to the South Pole
being situated near the middle of the continent. Theoretically
Antarctica would be located in all time zones; however, areas south of
the Antarctic Circle experience extreme day-night cycles near the
times of the June and December solstices, making it difficult to
determine which time zone would be appropriate. For practical purposes
time zones are usually based on territorial claims; however, many
stations use the time of the country they are owned by or the time
zone of their supply base (e.g. McMurdo Station and Amundsen–Scott
South Pole Station use New Zealand time due to their main supply base
beingChristchurch, New Zealand).[1] Nearby stations can have different
time zones, due to their belonging to different countries. Many areas
have no time zone since nothing is decided and there are not even any
temporary settlements that have any clocks. They are simply labeled
with UTC time.[2]
"""

Then there's a list of "standard" UTC offsets for various Antarctica
locations, varying from -4 to +12.