var writer = require('./') var ws = writer(write, flush) ws.on('finish', function () { console.log('finished') }) ws.write('hello') ws.write('world') ws.end() function write (data, enc, cb) { // i am your normal ._write method console.log('writing', data.toString()) cb() } function flush (cb) { // i am called before finish is emitted setTimeout(cb, 1000) // wait 1 sec }