Lists known AMP Caches, as available at https://cdn.ampproject.org/caches.json.
By default, it uses a one-behind strategy to fetch the caches. This can be customised by passing a custom fetch strategy to the constructor.
const Caches = require('amp-toolbox-cache-list');
// Lists known AMP Caches
const caches = await new Caches().list();
// Retrieves a specific AMP cache
const googleAmpCache = await caches.get('google');