This avoids the following:
- checking that each item in the nodelist is a subclass of Node,
- calling str() on the render_annotated() output, because it's
documented that Node.render() must return a string,
- calling mark_safe() on the output, when the value to be wrapped is
definitively known to be a string because the result of ''.join()
is always of that type,
- using an intermediate list to store each individual string.
854e9b0668