const it = ["Блокнот", "Пенал"][Symbol.iterator]();
console.log(it.next(), it.next(), it.next());

const shelf = {
  items: ["Блокнот", "Пенал"],
  [Symbol.iterator]() { return this.items[Symbol.iterator](); }
};
console.log([...shelf]);

function* numbers() {
  yield 1;
  yield 2;
}
console.log([...numbers()]);

function* orderIds() {
  let id = 1040;
  while (true) yield id++;
}
const ids = orderIds();
console.log(ids.next().value, ids.next().value);

function* coffee() { yield "Блокнот"; yield "Пенал"; }
function* shelf() { yield* coffee(); yield "Стикер"; }
console.log([...shelf()]);

function* g() {
  try { yield 1; yield 2; } finally { console.log("Уборка"); }
}
const it = g();
console.log(it.next());
console.log(it.return("стоп"));