Solution for Writing Transforms using concat-stream?

[byudaniel]

I'm having trouble understanding how I could use concat-stream to get the solution to the "Writing Transforms" problem. Any ideas?

var through = require('through2');
var concat = require('concat-stream');
var sprintf = require('sprintf');

module.exports = function(file) {
    if (!/\.txt$/.test(file)) {
        return through();
    }

    var stream = through();

    stream.pipe(concat(function(text) {
        // How can I pipe result to stream?
    }));

    return stream;
};