e文不好，帮看看这句话么意思

zhwly

'o'  Signed octal value. (1)
The alternate form causes a leading zero ('0') to be inserted between left-hand padding and the formatting of the number if the leading character of the result is not already a zero.

上面是python帮助文档中关于字符串格式化操作的一段，上面那段话是什么意思啊。o是转换成有符号8进制数，下面那句看不懂了