How to use the event-stream.through function in event-stream

exports.patch = function(opts) {
	var pass = es.through();

	var src = pass
		.pipe(updateSandboxHelperPermissions())
		.pipe(opts.keepDefaultApp ? es.through() : removeDefaultApp())
		.pipe(renameApp(opts));

	return es.duplex(pass, src);
};

exports.patch = function(opts) {
	var pass = es.through();

	var src = pass
		.pipe(opts.keepDefaultApp ? es.through() : removeDefaultApp())
		.pipe(patchExecutable(opts))
		.pipe(renameApp(opts));

	return es.duplex(pass, src);
};

var addSrc = function() {
    var pass = es.through();
    return es.duplex(pass, es.merge(gulp.src.apply(gulp.src, arguments), pass));
};

var addSrc = function() {
    var pass = es.through();
    return es.duplex(pass, es.merge(gulp.src.apply(gulp.src, arguments), pass));
};

var addSrc = function() {
    var pass = es.through();
    return es.duplex(pass, es.merge(gulp.src.apply(gulp.src, arguments), pass));
};