better way to invert case of string

Question

I am learning python and meet an exercise:

Strings. Create a function that will return another string similar to the input string, but with its case i

Answer 1

Your solution is perfectly fine. You don't need three branches though, because str.upper() will return str when upper is not applicable anyway.

With generator expressions, this can be shortened to:

>>> name = 'Mr.Ed'
>>> ''.join(c.lower() if c.isupper() else c.upper() for c in name)
'mR.eD'