Get the response corresponding to a request, but only if it
        hasn't been played back before, and mark it as played

def play_response(self, request):
        """
        Get the response corresponding to a request, but only if it
        hasn't been played back before, and mark it as played
        """
        for index, response in self._responses(request):
            if self.play_counts[index] == 0:
                self.play_counts[index] += 1
                return response
        # The cassette doesn't contain the request asked for.
        raise UnhandledHTTPRequestError(
            "The cassette (%r) doesn't contain the request (%r) asked for"
            % (self._path, request)
        )