code: def bump(self):
          
          # read client
          values = self.client.mget(self.keys.indicator, self.keys.dispenser)
          indicator, dispenser = map(int, values)
  
          # determine active users
          numbers = range(indicator, dispenser + 1)
          keys = [self.keys.key(n) for n in numbers]
          pairs = zip(keys, self.client.mget(*keys))
  
          try:
              # determine number of first active user
              number = next(self.keys.number(key)
                            for key, value in pairs if value is not None)
          except:
              # set number to next result of incr on dispenser
              number = dispenser + 1
  
          # set indicator to it if necessary
          if number != indicator:
              self.client.set(self.keys.indicator, number)
  
          # announce and return it anyway
          self.announce(number)
          return number
docs: Fix indicator in case of unnanounced departments.