docs: def get_adjusted_value(
              self,
              assets,
              field,
              dt,
              perspective_dt,
              data_frequency):
          '''
          TODO:
          for external data (fetch_csv) support, need to update logic here.
          '''
          return self.backend.get_spot_value(
              assets, field, dt, data_frequency, self.quantopian_compatible
          )