Promise.coroutine (No coroutine - just promises)

promises.js

var Promise = require('bluebird');
var request = require('request');
var fs = require('fs');

request_promise = Promise.promisify(request);
writeFile_promise = Promise.promisify(fs.writeFile);

request_promise('https://s3.amazonaws.com/aaronblondeau/widgets/widgets.json')
.then((response, body) => {
	var data = JSON.parse(response.body);
	return writeFile_promise('./widgets.json', JSON.stringify(data.widgets));
})
.then(() => {
	console.log("Done")
})
.catch((err) => {
	// This a bit better for catching errors
	console.error(err);
});