code: def get_shard_by_num(self, shard_num):
          
          if shard_num < 0 or shard_num >= self.num_shards():
              raise ValueError("requested invalid shard# {0}".format(shard_num))
  
          return self._shards[shard_num]
docs: get_shard_by_num returns the shard at index shard_num.
  
          Keyword arguments:
          shard_num -- The shard index
  
          Returns a redis.StrictRedis connection or raises a ValueError.