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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def run_request_processors(self, request):
 """ Before rendering a page, run all registered request processors. A request processor may peruse and modify the page or the request. It can also return a ``HttpResponse`` for shortcutting the rendering and returning that response immediately to the client. """

        if not getattr(self, 'request_processors', None):
            return

        for fn in reversed(list(self.request_processors.values())):
            r = fn(self, request)
            if r:
                return r