<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _clearPrices(self):
 """ Clears prices according to auction type. """

        for offbid in self.offers + self.bids:
            if self.auctionType == DISCRIMINATIVE:
                offbid.clearedPrice = offbid.price
            elif self.auctionType == FIRST_PRICE:
                offbid.clearedPrice = offbid.lmbda
            else:
                raise ValueError