> For the complete documentation index, see [llms.txt](https://once-upon-a-phd.gitbook.io/once-upon-a-phd/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://once-upon-a-phd.gitbook.io/once-upon-a-phd/en/roam/guan-yu-2012.md).

# What About 2012