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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 get_redirect(self):
 """ Returns the previous url. """

        index_url = self.appbuilder.get_url_for_index
        page_history = Stack(session.get("page_history", []))

        if page_history.pop() is None:
            return index_url
        session["page_history"] = page_history.to_json()
        url = page_history.pop() or index_url
        return url