The exception is right there. It's an index error, that is it's trying to do something going beyond the range of what this thing could deal with.

但他事实上抛出一个异常，异常就在这里，这是一个下标错误,它是试图去取超出范围的元素造成的。

麻省理工公开课 - 计算机科学及编程导论课程节选

It's really a technology initiative that's aimed to index the "dark" web or the hidden web, because according to computer scientists, right now the conditional search engines only index about 1% of the information on the Internet.

这是一项,致力于将暗网,或隐藏网页纳入索引的技术创新，根据计算机科学家的统计，条件式的搜索引擎只将,互联网上1%的信息纳入了索引。

斯坦福公开课 - 百度CEO李彦宏演讲：全球最大搜索引擎的发展课程节选