You don't want to use this class. Really. Use
XPath, which is a wrapper for this class. Believe me. You don't want to poke around in here. There is strange, dark magic at work in this code. Beware. Go back! Go back while you still can!
Performs a depth-first (document order)
XPath search, and returns the first match. This is the fastest, lightest way to return a single result.
FIXME: This method is incomplete!