Subscribing to store changes

If you want to be notified whenever the store state changes, you can use the subscribe method to register a callback function.
This method returns a function which can be invoked later for unsubscription.

// An initialised store. Params omitted for brevity
const store = createAppState('', {

// Subscribe to changes in the store
const unsubscribe = store.subscribe(() => {
// this callback is invoked whenever the store changes
console.log('Store has changed!')

// Unsubscribe later