Retrieves one or more items from the storage area. Accepts an array of string keys to identify the item(s) to be retrieved, or null to return all data. Returns a Promise that resolves to an object containing every matching item.
Stores one or more items in the storage area, or updates existing items. Returns a Promise that will be fulfilled with no arguments if the operation succeeded.
Platform-dependent data storage class. For example, when using this library in a browser extension, the storage.local API is compatible. Other platforms may have other ways of dealing with local storage, but it is sufficient to create a small layer for storage to have the specified methods.