Request realtime 5 second bars.

        https://interactivebrokers.github.io/tws-api/realtime_bars.html

        Args:
            contract: Contract of interest.
            barSize: Must be 5.
            whatToShow: Specifies the source for constructing bars.
                Can be 'TRADES', 'MIDPOINT', 'BID' or 'ASK'.
            useRTH: If True then only show data from within Regular
                Trading Hours, if False then show all data.
            realTimeBarsOptions: Unknown.

def reqRealTimeBars(
            self, contract: Contract, barSize: int,
            whatToShow: str, useRTH: bool,
            realTimeBarsOptions: List[TagValue] = None) -> RealTimeBarList:
        """
        Request realtime 5 second bars.

        https://interactivebrokers.github.io/tws-api/realtime_bars.html

        Args:
            contract: Contract of interest.
            barSize: Must be 5.
            whatToShow: Specifies the source for constructing bars.
                Can be 'TRADES', 'MIDPOINT', 'BID' or 'ASK'.
            useRTH: If True then only show data from within Regular
                Trading Hours, if False then show all data.
            realTimeBarsOptions: Unknown.
        """
        reqId = self.client.getReqId()
        bars = RealTimeBarList()
        bars.reqId = reqId
        bars.contract = contract
        bars.barSize = barSize
        bars.whatToShow = whatToShow
        bars.useRTH = useRTH
        bars.realTimeBarsOptions = realTimeBarsOptions
        self.wrapper.startSubscription(reqId, bars, contract)
        self.client.reqRealTimeBars(
            reqId, contract, barSize, whatToShow, useRTH, realTimeBarsOptions)
        return bars