'Returns the previous url.'

def get_redirect(self):

    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
