Node js TransformStream


## Duplex & read write transformable
### example
`zlib.createGzip` 


```typeconst { Transform } = require("stream")const upperCaseTr = new Transform({	readableObjectMode: true  transform(chunk, encoding, callback) {    this.push(chunk.toString().toUpperCase())    callback()  },})process.stdin.pipe(upperCaseTr).pipe(process.stdout)```
change to upper




> [Node.js Stream 당신이 알아야할 모든 것 3편](https://jeonghwan-kim.github.io/node/2017/08/12/node-stream-you-need-to-know-3.html)




