在python中将一些字符串（utf-8或其他）转换为简单的ASCII字符串的简单方法是什么？

Inside my python scrip, I get some string back from a function which I didn't write. The encoding of it varies. I need to convert it to ascii format. Is there some fool-proof way of doing this? I don't mind replacing the non-ascii chars with blanks or something else...Inside my python scrip, I get some string back