gistfile1.as

import calendar
import time
import pytz
import datetime as DT

utc = pytz.timezone('UTC')

for tzname in [name for name in pytz.all_timezones if 'Brazil' in name]:
    tz1 = pytz.timezone(tzname)
    date = utc.localize(DT.datetime(2013, 1, 1))
    print(tzname)
    while date.year == 2013:
        now_tz = date.astimezone(tz1)
        now_epoch = calendar.timegm(now_tz.utctimetuple())
        begin_day = now_tz.replace(hour=0, minute=0, second=0)
        try:
            assert now_tz.utcoffset() == begin_day.utcoffset()
        except AssertionError:
            print(date)
            print(repr(now_tz))
            print(repr(begin_day))
            print(now_tz.utcoffset(), begin_day.utcoffset())
            print('-'*80)
        date = date + DT.timedelta(hours=1)