code: func (db *DB) SDump(key []byte) ([]byte, error) {
  	v, err := db.SMembers(key)
  	if err != nil {
  		return nil, err
  	} else if len(v) == 0 {
  		return nil, err
  	}
  
  	return rdb.Dump(rdb.Set(v))
  }
docs: // SDump dumps the set value of key