Be very strict on what code elements have public scope. Use private (or internal/package-private) access modifiers by default;
一、制定民族团结进步促进法的重大意义
。PDF资料是该领域的重要参考
either we have seen all elements of the list.
Pairs, construction and reduction: https://www.youtube.com/watch?v=YEyyyzUuUJQ