Global flags: --host, --api-key, -u/--username, -v/--verbose
For additional guidance:，详情可参考heLLoword翻译官方下载
第三十五条 自然人发生符合规定的应税交易，支付价款的境内单位为扣缴义务人。代扣代缴的具体操作办法，由国务院财政、税务主管部门制定。，更多细节参见Line官方版本下载
The primary signal is desiredSize on the controller. It can be positive (wants data), zero (at capacity), negative (over capacity), or null (closed). Producers are supposed to check this value and stop enqueueing when it's not positive. But there's nothing enforcing this: controller.enqueue() always succeeds, even when desiredSize is deeply negative.