= 3. Defaults to '/' but if it's None
        will be the ID3v2v2.4 null separator.
    padding (:obj:`mutagen.PaddingFunction`)

Raises:
    mutagen.MutagenError

By default Mutagen saves ID3v2.4 tags. If you want to save ID3v2.3
tags, you must call method update_to_v23 before saving the file.

The lack of a way to update only an ID3v1 tag is intentional.
r