Method __iterator

src/List.js:212–221

(type, reverse)

  }

  __iterator(type, reverse) {
    let index = reverse ? this.size : 0;
    const values = iterateList(this, reverse);
    return new Iterator(() => {
      const value = values();
      return value === DONE
        ? iteratorDone()
        : iteratorValue(type, reverse ? --index : index++, value);
    });
  }

  __iterate(fn, reverse) {
    let index = reverse ? this.size : 0;