code: def add_tags(self, ID3=None):
          
  
          if ID3 is None:
              ID3 = self.ID3
          if self.tags is None:
              self.ID3 = ID3
              self.tags = ID3()
          else:
              raise error("an ID3 tag already exists")
docs: Add an empty ID3 tag to the file.
  
          Args:
              ID3 (ID3): An ID3 subclass to use or `None` to use the one
                  that used when loading.
  
          A custom tag reader may be used in instead of the default
          `ID3` object, e.g. an `mutagen.easyid3.EasyID3` reader.