MDN Interation:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols

• iteration : 반복, 순회
• iteration protocol : 반복 가능한 인터페이스 (규격, 약속)
• iteration - class / iterable - interface 명명

[Symbol.iterator](): IterableIterator<T>;

1) iterable 살펴보기

2) quiz

3) generator

4) spread

5) destructuring assignment