gistfile1.js

const Bluebird = require('bluebird');
const fs = Bluebird.promisifyAll(require('fs'));

const getFilenamesContainingMichaelAsync = Bluebird.coroutine(function* (path) {
    const filenames = yield fs.readdirAsync(path);
    return filenames.filter(name => name.indexOf('Michael') !== -1);
});

Bluebird.coroutine(function* () {
    const filenamesContainingMichael = yield getFilenamesContainingMichaelAsync('~/some_dir');
    console.log(filenamesContainingMichael);
})();