text: 'use strict'
  
  const { Readable, Writable } = require('readable-stream')
  
  var i = 20
  
  const rs = Readable({
    read: (size) => {
      setImmediate(function () {
        rs.push(i-- ? Buffer.alloc(size) : null)
      })
    }
  })
  
  const ws = Writable({
    write: (chunk, enc, cb) => {
      console.log(ws._writableState.length)
      setTimeout(cb, 1)
    }
  })
  
  rs.on('data', (chunk) => ws.write(chunk))