TODO:
        for external data (fetch_csv) support, need to update logic here.

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
        )