我如何在python中创建自定义列表类？

class CustomList(list):
    def __init__(self, *args):
        super().__init__(*args)

    def append(self, item):
        if not isinstance(item, (int, float)):
            raise ValueError("CustomList只接受数字类型的元素")
        super().append(item)

    def insert(self, index, item):
        if not isinstance(item, (int, float)):
            raise ValueError("CustomList只接受数字类型的元素")
        super().insert(index, item)

    def extend(self, items):
        for item in items:
            if not isinstance(item, (int, float)):
                raise ValueError("CustomList只接受数字类型的元素")
        super().extend(items)

    def __add__(self, other):
        if not isinstance(other, CustomList):
            raise ValueError("只能将CustomList对象相加")
        result = CustomList(self)
        result.extend(other)
        return result

    def __iadd__(self, other):
        self.extend(other)
        return self

# 创建一个CustomList对象
my_list = CustomList([1, 2, 3])

# 向CustomList对象中添加元素
my_list.append(4)
my_list.insert(0, 0)
my_list.extend([5, 6])

# 使用加法操作符将两个CustomList对象相加
my_list2 = CustomList([7, 8, 9])
my_list3 = my_list + my_list2

# 输出CustomList对象的内容
print(my_list)  # 输出：[0, 1, 2, 3, 4, 5, 6]
print(my_list3)  # 输出：[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]