_appendIterators(iterators) {
		if (this._unsortedItems.size > 0)
			iterators.push(this._unsortedItems[Symbol.iterator]());
		for (const key of this._keys) {
			const entry = this._map.get(key);
			if (this._leaf) {
				const leafEntry = /** @type {SortableSet<T>} */ (entry);
				const iterator = leafEntry[Symbol.iterator]();
				iterators.push(iterator);
			} else {
				const nodeEntry =
					/** @type {LazyBucketSortedSet<T, K>} */
					(entry);
				nodeEntry._appendIterators(iterators);
			}
		}
	}
@param {Iterator<T>[]} iterators list of iterators to append to
@returns {void}