def set(att, val)
      if val.to_s.empty?
        key.call("HDEL", att)
      else
        key.call("HSET", att, val)
      end

      @attributes[att] = val
    end
def set(att, val)
      if val.to_s.empty?
        key.call("HDEL", att)
      else
        key.call("HSET", att, val)
      end

      @attributes[att] = val
    end
Update an attribute value atomically. The best usecase for this
 is when you simply want to update one value.

 Note: This method is dangerous because it doesn't update indices
 and uniques. Use it wisely. The safe equivalent is `update`.