code example for preserving cart state article

on load observable 2

onLoad$ = this.auth.user$.pipe(
  take(1), // we only do this once as we only want to handle the initial load
  switchMap(user => !!user ? mergedCartStates$ : cartStateFromStorage$),
  // set the cart form with the retrieved state's value
  tap(setCartValue) // set the cart's form with emitted value
);