最近编辑 html，发现有须要折叠代码，查了一下，做个笔记。
- set foldmethod=manual
- 在某个标签处，
zfat或zfit能够创立一个折叠，而后用za就能够关上或者敞开一个折叠，
I have found zfat (or, equally, zfit) works well for folding with HTML documents. za will toggle (open or close) an existing fold. zR opens all the folds in the current document, zM effectively re-enables all existing folds marked in the document.