casefold() method converts a string into lowercase.
This method is similar to the lower() method, but the casefold() method is more aggressive by removing all the case distinctions present in a string.
|String||Returns a string where all the characters are converted into lowercase.|
In the following example, the letter ß is called Eszett, literally meaning s z. However, when the letter is not available (or when a word is in all caps), ß is almost always substituted by the digraph ss rather than sz.