def last(symbol: str):
    """ displays last price, for symbol if provided """
    app = PriceDbApplication()

    # convert to uppercase
    if symbol:
        symbol = symbol.upper()
        # extract namespace
        sec_symbol = SecuritySymbol("", "")
        sec_symbol.parse(symbol)

        latest = app.get_latest_price(sec_symbol)
        assert isinstance(latest, PriceModel)
        print(f"{latest}")
    else:
        # Show the latest prices available for all securities.
        latest = app.get_latest_prices()
        for price in latest:
            print(f"{price}")
displays last price, for symbol if provided