How to use the akshare.futures_derivative.cons.xgx_main_url.format function in akshare

def futures_xgx_index(
    symbol: str = 67,
    start_date: str = "2000-10-01",
    end_date: str = "2020-04-17",
    plot: bool = True,
) -> pd.DataFrame:
    session = _get_code_pic()
    value = input()
    payload = {"txtStartTime": start_date, "txtEndTime": end_date, "txtyzcode": value}
    res = session.post(xgx_main_url.format(symbol), data=payload, headers=xgx_headers)
    soup = BeautifulSoup(res.text, "lxml")

    table_df = pd.read_html(res.text)[0]
    table_df.index = pd.to_datetime(table_df["日期"])
    del table_df["日期"]
    if plot:
        table_df["值"].plot()
        plt.title(
            soup.find("div", attrs={"class": "commodity_right"}).find("h5").get_text()
        )
        plt.xlabel("日期")
        plt.ylabel("值")
        plt.show()
        return table_df
    else:
        return table_df