>>> h1
text
===

<<<
<h1>text</h1>
>>> h2
text
---

<<<
<h2>text</h2>
>>> h1 bar on first line becomes text
===

<<<
<p>===</p>
>>> h2 bar on first line becomes list
-

<<<
<ul><li></li></ul>
>>> can be multiline
header
on two lines
==

<<<
<h1>header
on two lines</h1>