事件：'finish'

¥Event: 'finish'

'finish' 事件来自 stream.Writable 类。'finish' 事件在 stream.end() 被调用并且所有块都已被 stream._transform() 处理后触发。在出现错误的情况下，不应触发 'finish'。

¥The 'finish' event is from the stream.Writable class. The 'finish' event is emitted after stream.end() is called and all chunks have been processed by stream._transform(). In the case of an error, 'finish' should not be emitted.