> For the complete documentation index, see [llms.txt](https://www.oulan.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://www.oulan.com/2019/04/15.md).

# 15

<figure><img src="/files/dFwlxq829gA49J7u8G6x" alt=""><figcaption></figcaption></figure>