通过仅提供"left()"和"right()"作为命令,使用光标通过嵌套列表手动导航？

class NestedListNavigator:
    def __init__(self, nested_list):
        self.stack = []
        self.stack.append(('root', nested_list))

    def left(self):
        if len(self.stack) > 1:
            self.stack.pop()

    def right(self, index):
        current_level, current_list = self.stack[-1]
        if isinstance(current_list[index], list):
            self.stack.append((current_level + 1, current_list[index]))

    def get_current_element(self):
        return self.stack[-1][1]

nested_list = [1, [2, 3], 4, [5, [6, 7], 8], 9]
navigator = NestedListNavigator(nested_list)

print(navigator.get_current_element())  # 输出：[1, [2, 3], 4, [5, [6, 7], 8], 9]
navigator.right(1)
print(navigator.get_current_element())  # 输出：[2, 3]
navigator.right(0)
print(navigator.get_current_element())  # 输出：2
navigator.left()
print(navigator.get_current_element())  # 输出：[2, 3]
navigator.right(1)
print(navigator.get_current_element())  # 输出：3