wtfES6

let fibonacci = {
  [Symbol.iterator]() {
    let pre = 0, cur = 1;
    return {
      next(p) {
          console.log(p);
        pre = cur
        cur = pre + cur
        //[pre, cur] = [cur, pre + cur];
        if (cur < 100) {
        return { done: false, value: cur }
        } else {
          return {done: true}
        }
      }
    }
  }
}