Generating LaTeX reports from XML *without* external scripts

Question

First of all, I apologize if this is pretty similiar in nature to my previous question: Reading and (custom) formatting a CSV (not \csvautotabular)

I thought it would be better to separate the two for future reference.

Also, converting to CSV is not always an option, if you have some serious XMLs.

So, here is the deal - I have an XML file that - suppose - looks like this:

<root>
<foo>
 <bar>Boom</bar>
 <baz>Bang</baz>
</foo>
<foo>
 <bar>Zip</bar>
 <baz>Zoom</baz>
 <bak>Boing</bak>
</foo>
</root>

I would like to obtain something along the lines of:

\begin{Foo}
  \Bar{Zoom}
  \Baz{Bang}
\end{Foo}
\begin{Foo}
  \Bar{Zip}
  \Baz{Zoom}
  \Bak{Bang}
\end{Foo}

ATM I'm doing this with a couple of python lines the output of which I then proceed to \include it in my main file, but it would be nice not having to depend on an external script, especially since I'm not the only one working on the document.

Any hint is appreciated.