[[:en:Template:Did you know/Queue/NextPrep]] contains:
4<noinclude> <!-- There is no Prep 8! -->
{{documentation|content=This number indicates the next DYK prep set to move into the
queue.}}
</noinclude>
What I want to get is just the "4". Is Page.extract() what I'm looking for?
Experimentally, it does what I want, but it's not clear if this is actually the
intended use case.