code: def get_day_start_ut(self, date):
          
          if isinstance(date, string_types):
              date = datetime.datetime.strptime(date, '%Y-%m-%d')
  
          date_noon = datetime.datetime(date.year, date.month, date.day, 12, 0, 0)
          ut_noon = self.unlocalized_datetime_to_ut_seconds(date_noon)
          return ut_noon - 12 * 60 * 60
docs: Get day start time (as specified by GTFS) as unix time in seconds
  
          Parameters
          ----------
          date : str | unicode | datetime.datetime
              something describing the date
  
          Returns
          -------
          day_start_ut : int
              start time of the day in unixtime