How to reformat URLs to be more restful (from .../?id=123 to .../123)?

Programmer Question

Currently I have pages accessed via:

www.foo.com/details.html?id=123

I'd like to make them more restful-like, such as by the following:

www.foo.com/details/123

I'm using Google App Engine. Currently the URL's are mapped in the html-mappings file:

 ('/details.html*', DetailsPage),

And then on the DetailsPage handler, it fetches the ID value via:

class DetailsPage(webapp.RequestHandler):
    def get(self):
        announcement_id = self.request.get("id")

How might I restructure this so that it can map the URL and a extract the ID via the other-formatted URL: www.foo.com/details/123

Thanks

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