code: def get(self, now):
          
  
          items = self.script(keys=[self.key], args=[now - self.min_age])
          return items[0] if items else None
docs: Get a bucket key to compact.  If none are available, returns
          None.  This uses a Lua script to ensure that the bucket key is
          popped off the sorted set in an atomic fashion.
  
          :param now: The current time, as a float.  Used to ensure the
                      bucket key has been aged sufficiently to be
                      quiescent.
  
          :returns: A bucket key ready for compaction, or None if no
                    bucket keys are available or none have aged
                    sufficiently.