使用Python中的字典替换字符串中的字符

我研究过使用字典的字符替换，但我仍然无法让我的代码正常工作。我的代码如下：

I have researched about character replacement using dictionaries but I still cannot get my code to work properly. My code goes like this:

def encode(code,msg):  
    for k in code:  
        msg = msg.replace(k,code[k])  
    return msg

，当我运行代码：

Now, when I run the code:

code = {'e':'x','x':'e'}
msg = "Jimi Hendrix"
encode(code,msg)

给我Jimi Hxndrix而不是Jimi Hxndrie。如何获得字母'x'替换为'e'？

It gives me "Jimi Hxndrix" instead of "Jimi Hxndrie". How do I get the letter 'x' to be replaced by 'e' also?