See: https://core.telegram.org/bots/api#answerprecheckoutquery

def answerPreCheckoutQuery(self, pre_checkout_query_id, ok,
                               error_message=None):
        """ See: https://core.telegram.org/bots/api#answerprecheckoutquery """
        p = _strip(locals())
        return self._api_request('answerPreCheckoutQuery', _rectify(p))