Remove <p/>
and <ab/>
elements that are children of <head/>
by stripping the target tag. Children of the target are added as children of <head/>
and text and tail of the target are added at the appropriate position.
If both the <head/>
parent and the target contain text, a new <lb/>
is added to mark the boundary between the text parts.
Before transformation:
<div>
<head>text1
<p>text2</p>
</head>
<head>
<p>text3</p>
</head>
<head>text4
<ab>
<hi>text5</hi>
</ab>
</head>
</div>
After transformation:
<div>
<head>text1<lb/>text2</head>
<head>text3</head>
<head>text4
<hi>text5</hi>
</head>
</div>