Fix Python – How to change a string into uppercase

I have problem in changing a string into uppercase with Python. In my research, I got string.ascii_uppercase but it doesn’t work.
The following code:
>>s = ‘sdsd’
>>s.ascii_uppercase

Gives this error message:
Traceback (most recent call last):
File ““, line 1, in
AttributeError: ‘str’ object has no attribute ‘ascii_uppercase….