code: def _cleanup(self):
          
          if self.todolist.exists():
              try:
                  saved_todo = iter(open(self.todolist, encoding="utf-8"))
                  int(next(saved_todo).strip())
                  for line in saved_todo:
                      _, serial = line.strip().split()
                      int(serial)
              except (StopIteration, ValueError):
                  # The todo list was inconsistent. This may happen if we get
                  # killed e.g. by the timeout wrapper. Just remove it - we'll
                  # just have to do whatever happened since the last successful
                  # sync.
                  logger.info("Removing inconsistent todo list.")
                  self.todolist.unlink()
docs: Does a couple of cleanup tasks to ensure consistent data for later
          processing.