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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 hasBidAsk(self) -> bool: """ See if this ticker has a valid bid and ask. """

        return (
            self.bid != -1 and not isNan(self.bid) and self.bidSize > 0 and
            self.ask != -1 and not isNan(self.ask) and self.askSize > 0)