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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 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