Bluebird's `promisifyAll()` is just a way to generalize that pattern, so that you don't need to write it yourself. And if you care about performance it's substa

Bluebird's `promisifyAll()` is just a way to generalize that pattern, so that you don't need to write it yourself. And if you care about performance it's substantially faster too. If you want to learn about the pattern then fine, but personally I don't want to write that for every single `fs` function I use in a project, it's much more convenient to just `Bluebird.promisifyAll(require('fs'))`.