code: def add_note(self, player, text, label=None, update=None):
          
          if label is not None and (label not in self.label_names):
              raise LabelNotFoundError('Invalid label: {}'.format(label))
          if update is None:
              update = datetime.utcnow()
          # converted to timestamp, rounded to ones
          update = update.strftime('%s')
          label_id = self._get_label_id(label)
          new_note = etree.Element('note', player=player, label=label_id, update=update)
          new_note.text = text
          self.root.append(new_note)
docs: Add a note to the xml. If update param is None, it will be the current time.