code: def _withholdOffbids(self):
          
          limits = self.limits
  
          # Eliminate offers (but not bids) above 'price_cap'.
          if not limits.has_key('max_offer'):
              limits['max_offer'] = self.priceCap
  
          # Limit cleared offer prices after locational adjustments.
          if not self.limits.has_key('maxClearedOffer'):
              self.limits['maxClearedOffer'] = self.priceCap
  
          # Withhold invalid offers/bids.
          for offer in self.offers:
              if round(offer.quantity, 4) <= 0.0:
                  logger.info("Withholding non-posistive quantity [%.2f] "
                              "offer." % offer.quantity)
                  offer.withheld = True
  
          for bid in self.bids:
              if round(bid.quantity, 4) <= 0.0:
                  logger.info("Withholding non-posistive quantity [%.2f] "
                              "bid." % bid.quantity)
                  bid.withheld = True
  
          # Optionally, withhold offers/bids beyond price limits.
          if limits.has_key("maxOffer"):
              for offer in self.offers:
                  if offer.price > limits["maxOffer"]:
                      logger.info("Offer price [%.2f] above limit [%.3f], "
                          "withholding." % (offer.price, limits["maxOffer"]))
                      offer.withheld = True
  
          if limits.has_key("minBid"):
              for bid in self.bids:
                  if bid.price < limits["minBid"]:
                      logger.info("Bid price [%.2f] below limit [%.2f], "
                          "withholding." % (bid.price, limits["minBid"]))
                      bid.withheld = True
docs: Withholds offers/bids with invalid (<= 0.0) quantities or prices
              outwith the set limits.