in lib/twitter_cldr/timezones/generic_location.rb [177:187]
def use_standard?(date_int, transition_offset)
prev_trans = tz.transitions_up_to(Time.at(date_int - DST_CHECK_RANGE)).last
next_trans = tz.transitions_up_to(Time.at(date_int + DST_CHECK_RANGE)).last
return false if transition_offset.std_offset != 0
return false if prev_trans && prev_trans.offset.std_offset != 0
return false if next_trans && next_trans.offset.std_offset != 0
true
end