kubk

const store = makeAutoObservable({
  shop: {
    taxPercent: 8,
    items: [
      { name: 'apple', value: 1.20 },
      { name: 'orange', value: 0.95 },
    ]
  },
  get subtotal() {
    return this.shop.items.reduce((acc, item) => acc + item.value, 0);

kubk

interface Observer<T> {
    next(value: T)
    complete()
    error(error: unknown)
}

class Observable<T> {
    constructor(public subscribe: (observer: Observer<T>) => void) {}

    map(mapper: (x: T) => T): Observable<T> {