code: def stats(self, keys=None, keystats=False):
          
          if keys and not isinstance(keys, (tuple, list)):
              keys = (keys,)
          return self._stats(keys, keystats=keystats)
docs: Request server statistics.
  
          Fetches stats from each node in the cluster. Without a key
          specified the server will respond with a default set of
          statistical information. It returns the a `dict` with stats keys
          and node-value pairs as a value.
  
          :param keys: One or several stats to query
          :type keys: string or list of string
          :raise: :exc:`.CouchbaseNetworkError`
          :return: `dict` where keys are stat keys and values are
              host-value pairs
  
          Find out how many items are in the bucket::
  
              total = 0
              for key, value in cb.stats()['total_items'].items():
                  total += value
  
          Get memory stats (works on couchbase buckets)::
  
              cb.stats('memory')
              # {'mem_used': {...}, ...}