Return the path pattern used when routing a request. (Tornado<4.5)

        :rtype: str

def _get_path_pattern_tornado4(self):
        """Return the path pattern used when routing a request. (Tornado<4.5)

        :rtype: str
        """
        for host, handlers in self.application.handlers:
            if host.match(self.request.host):
                for handler in handlers:
                    if handler.regex.match(self.request.path):
                        return handler.regex.pattern