Confusion with datetime 'dst' function result

[Gribouillis]

I'm not able to answer the question but from what I read elsewhere, using the arrow module could be the solution to these issues.

>>> import arrow
>>> a = arrow.now('US/Eastern')
>>> a
<Arrow [2019-11-15T15:34:42.463220-05:00]>
>>> b = a.shift(days=-180)
>>> b
<Arrow [2019-05-19T15:34:42.463220-04:00]>
>>> a.dst()
datetime.timedelta(0)
>>> b.dst()
datetime.timedelta(0, 3600)