def METHOD_NAME(
    self,
    instrument_code: str,
    start_date: datetime.datetime,
    end_date: datetime.date,
) -> float:
    price_series = self.get_prices_for_instrument(instrument_code)
    change = get_percentage_change_from_series_for_period(
        price_series, start_date=start_date, end_date=end_date
    )
    return change