code: def perform(self, store, count):
          
          self.count = count
  
          try:
              self.upgradeStore(store)
              print 'Upgrade complete'
          except errors.ItemUpgradeError as e:
              print 'Upgrader error:'
              e.originalFailure.printTraceback(file=sys.stdout)
              print self.errorMessageFormat % (
                  e.oldType.typeName, e.storeID, e.oldType.schemaVersion,
                  e.newType.schemaVersion)
docs: Upgrade C{store} performing C{count} upgrades per transaction.
  
          Also, catch any exceptions and print out something useful.