var stream      = require('stream');var util            = require('util');var Excel           = require('exceljs');var fs          = require('fs');var writableStream  = fs.createWriteStream('./streamed1.xlsx');var ExcelTransform = function(options) {    stream.Transform.call(this, {        writableObjectMode: true,        readableObjectMode: false    });        this.workbook = options.workbook;    var self = this;    this.workbook.stream.on('readable', function() {        var chunk = workbook.stream.read();        self.push(chunk);    });    this.worksheet = options.worksheet;}util.inherits(ExcelTransform, stream.Transform);ExcelTransform.prototype._transform = function(doc, encoding, callback) {    this.worksheet.addRow({        name: doc.name    }).commit();    callback();};ExcelTransform.prototype._flush = function(callback) {    this.workbook.commit(); // final commit};// it's better to provide the workbook as a parameter to the ExcelTransformvar workbook = new Excel.stream.xlsx.WorkbookWriter();var worksheet = workbook.addWorksheet('sheet 1');worksheet.columns = [{    header: 'Name',    key: 'name'}];var rs = new stream.Readable({ objectMode: true });rs.push({ name: 'one' });// rs.push({ name: 'two' }); // uncomment me to see the bug vanishrs.push(null);rs.pipe(new ExcelTransform({    workbook: workbook,    worksheet: worksheet})).pipe(writableStream);