Followed a best practice in the time zones docs.

       >>> from django.utils.dateparse import parse_datetime

       >>> naive = parse_datetime("2012-02-21 10:28:45")

       >>> import pytz

       >>> pytz.timezone("Europe/Helsinki").localize(naive)

       >>> pytz.timezone("Europe/Helsinki").localize(naive, is_dst=None)

       datetime.datetime(2012, 2, 21, 10, 28, 45, tzinfo=<DstTzInfo 'Europe/Helsinki' EET+2:00:00 STD>)

   Note that ``localize`` is a pytz extension to the :class:`~datetime.tzinfo`