def back(self, n, _response):
        response = _response  # XXX move Browser._response into this class?
        while n > 0 or response is None:
            try:
                request, response = self._history.pop()
            except IndexError:
                raise BrowserStateError("already at start of history")
            n -= 1
        return request, response
dataset/ETHPy150Open deanhiller/databus/webapp/play1.3.x/samples-and-tests/i-am-a-developer/mechanize/_mechanize.py/History.back/original