<h1>One</h1>
<h2>Two</h2>
<h3>Three</h3>
<h4>Four</h4>
<h5>Five</h5>
<h6>Six</h6>
<p>####### Seven</p>
<h3>Three with</h3>
<h2>Spacing    doesn't    matter</h2>
<h2>Escaped final #</h2>
<p>## Not a header</p>
<p>#5 not a header</p>
<h2></h2>
<p>(empty header)</p>