code: def fetch_data(self):
          
          if relativedelta(self.end_date, self.start_date).years <= const.ONE_YEAR:
              data = self.request.send(self.symbol, self.start_date, self.end_date)
          else:
              data = self.fetch_chunk_data()
  
          return self.clean(data)
docs: Method returns results from response of Yahoo YQL API. It should returns always python list.