How to use the technical.history.__init__.OHLCV.exchange function in technical

if days:
        print("ignoring from data and fetching {}".format(days))
        from_date = (datetime.datetime.today() - datetime.timedelta(days=days)).timestamp()

    # generate exchange
    from technical.exchange import _create_exchange, historical_data
    ccxt_api = _create_exchange(ccxt_api)

    pair = pair.upper().split("/")
    stake = pair[1]
    asset = pair[0]

    # get newest data from the internal store for this pair

    latest_time = OHLCV.session.query(func.max(OHLCV.timestamp)).filter(
        OHLCV.exchange == ccxt_api.name,
        OHLCV.pair == "{}/{}".format(asset.upper(), stake.upper()),
        OHLCV.interval == interval
    ).one()[0]

    if force:
        print("forcing database refresh and downloading all data!")
        latest_time = None

    # add additional data on top
    if latest_time is None:

        # store data for all
        for row in historical_data(stake, asset, interval, from_date, ccxt_api):
            o = OHLCV(
                id="{}-{}-{}/{}:{}".format(ccxt_api.name, interval, asset.upper(), stake.upper(), row[0]),
                exchange=ccxt_api.name,