vs impact trade-off would need to be judged on a case-by-case basis. I
should all be made optional and given a default value，详情可参考搜狗输入法下载
[a-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]{2,}$ (280 256)，详情可参考快连下载安装
func (opt *Option) ArgInt32Var(val *int32) error，更多细节参见下载安装汽水音乐