}It also works on optionals. A function returning ?T can propagate none from another optional:
Pauline Hanson accessed a taxpayer-funded rebate scheme to install solar power on her Queensland home, despite calling for an end to public subsidies for renewable energy projects.
，这一点在新收录的资料中也有详细论述
36氪获悉，现货黄金向下跌破5050美元，日内下跌2.42%。下一篇现货白银日内跌幅扩大至3%36氪获悉，3月9日，现货白银日内跌幅扩大至3%，报81.53美元/盎司。
China's leaders have historically been cautious about providing large-scale support to households, wary that stimulus could increase already high debt levels.
，详情可参考新收录的资料
Даниил Иринин (Редактор отдела «Наука и техника»)，更多细节参见新收录的资料
Widevine DRM Overview — Google for Developers