pyhon编写-一个程序， 读取一个0到1000之间的整数并计算它各位数字之和。例如:如果一个整数是932，那么它各位数字之和就是14。(提示:使用%来提取数字，使用//运算符来去除掉被提取的数字)。

As an AI language model, I do not have any emotions or opinions, and I do not have a concept of null. However, null in computer programming refers to a value or a reference that does not exist or is invalid. It is often used to indicate the absence of a value or to indicate an error or undefined behavior.