How to use _get_selector_obj method in Airtest

...142        assert_value = False if self.assertion == 'assert_not_' else True143        if self.assertion:144            action = action_stack[-1]145            assert_result = self.obj == assert_value146            prev_selector_obj = self._get_selector_obj()147            # 必须预先判断所选对象是否存在，不存在的对象调用info属性时会抛出uiautomator.UiObjectNotFoundException148            # 因为即使是assert_not_checked时，也是可以获取对象info的149            if prev_selector_obj.obj.exists:150                uiobj = prev_selector_obj.obj.info151            else:152                uiobj = None153            assert_action = self.assertion + action154            genlog('assert', [assert_action, prev_selector_obj.selectors, assert_result] + list(args), uiobj)155            if not assert_result:156                try:157                    raise AutomatorAssertionFail('assert failed of {}, require {}, got {}'.format(assert_action, assert_value, self.obj))158                except AutomatorAssertionFail:159                    log_error('assert', traceback.format_exc(), assert_action, prev_selector_obj.selectors, assert_result, *args, **kwargs)160                    raise161            return None162        # handle selector expr163        if args or kwargs:164            if all([k in SELECTOR_ARGS for k in kwargs]):165                # get this select action name166                if len(action_stack) >= 1:167                    action = action_stack[-1]168                else:169                    action = 'global'170                # relative selector171                prev_selector_obj = self._get_selector_obj()172                if prev_selector_obj:173                    uiobj = try_getattr(prev_selector_obj.obj, 'info', prev_selector_obj.select_action, prev_selector_obj.selectors)174                    genlog('select', [prev_selector_obj.select_action, prev_selector_obj.selectors], uiobj)175                calling = try_call(self.obj, action, *args, **kwargs)176                ret = self.__class__(calling, self)177                ret.selectors = (args, kwargs) if args else kwargs178                ret.select_action = action179                return ret180        # 其他操作的log记录181        action, params = None, None182        if args or kwargs:183            last_log = list(args) or kwargs.values()184        else:185            last_log = []186        if len(action_stack) >= 3 and action_stack[-3] in TERTIARY_ACTION:187            taction = TERTIARY_ACTION[action_stack[-3]]188            if action_stack[-2] in taction:189                saction = taction[action_stack[-2]]190                if action_stack[-1] in saction:191                    action = action_stack[-3]192                    params = action_stack[-2:] + last_log193        if len(action_stack) >= 2 and action_stack[-2] in SECONDARY_ACTIONS:194            secondary_action = SECONDARY_ACTIONS[action_stack[-2]]195            if action_stack[-1] in secondary_action:196                action = action_stack[-2]197                params = action_stack[-1:] + last_log198        if len(action_stack) >= 1 and action_stack[-1] in PRIMARY_ACTION:199            action = action_stack[-1]200            params = last_log201        if action:202            # select操作log记录203            selector_obj = self._get_selector_obj()204            uiobj = None205            if selector_obj:206                uiobj = try_getattr(selector_obj.obj, 'info', selector_obj.select_action, selector_obj.selectors)207                genlog('select', [selector_obj.select_action, selector_obj.selectors], uiobj)208            genlog(action, params, uiobj)209        if not calling:210            calling = try_call(self.obj, 'action', *args, **kwargs)211        return self.__class__(calling, self)212    def __len__(self):213        return len(self.obj)214    def __nonzero__(self):215        """ python 2 only, for python 3, please override __bool__216        """217        return bool(self.obj)218    def __getitem__(self, item):219        return self.__class__(self.obj[item], self)220    def __iter__(self):221        objs, length = self, len(self)222        class Iter(object):223            def __init__(self):224                self.index = -1225            def next(self):226                self.index += 1227                if self.index < length:228                    return objs[self.index]229                else:230                    raise StopIteration()231            __next__ = next232        return Iter()233    def _get_selector_obj(self):234        # 下面的is not None的判断方法有点特殊235        # 因为该类实现了bool隐式转换接口，如果不这样判断的话，在and表达式返回时，还会自动bool隐式转换一次236        # 导致条件判断非预期237        ret = None238        if self.selectors:239            ret = self240        elif (self.parent and self.parent.selectors) is not None:241            ret = self.parent242        elif (self.parent and self.parent.parent and self.parent.parent.selectors) is not None:243            ret = self.parent.parent244        elif (self.parent and self.parent.parent and self.parent.parent.parent and self.parent.parent.parent.selectors) is not None:245            ret = self.parent.parent.parent246        return ret247    def end(self):...