We have an API that allows us to return a list of notes at `/notes`. We want to add the ability to sort that list by passing in the `sort` query param, which we read off of `req.query`. Once we know the expected sort order we pass a function to `Array.prototype.sort` that compares two notes' `lastEdited` values to decide which item comes first. A quick refresher about how [custom Array sort functions](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort) work in JavaScript. Sort takes a function with two params (which are items in the array). If the function returns true, the `a` item will be placed higher in the sorted array. If the function returns `false`, the `b` item will be placed higher. View the source for this project on the [projects github repo](https://github.com/xjamundx/egghead-express/).