code: def add_bookmark(self, name, time, chan=''):
          
          try:
              bookmarks = self.rater.find('bookmarks')
          except AttributeError:
              raise IndexError('You need to have at least one rater')
          new_bookmark = SubElement(bookmarks, 'bookmark')
          bookmark_name = SubElement(new_bookmark, 'bookmark_name')
          bookmark_name.text = name
          bookmark_time = SubElement(new_bookmark, 'bookmark_start')
          bookmark_time.text = str(time[0])
          bookmark_time = SubElement(new_bookmark, 'bookmark_end')
          bookmark_time.text = str(time[1])
  
          if isinstance(chan, (tuple, list)):
              chan = ', '.join(chan)
          event_chan = SubElement(new_bookmark, 'bookmark_chan')
          event_chan.text = chan
  
          self.save()
docs: Add a new bookmark
  
          Parameters
          ----------
          name : str
              name of the bookmark
          time : (float, float)
              float with start and end time in s
  
          Raises
          ------
          IndexError
              When there is no selected rater