code: def _handle_job_set(function):
      
      def call(self, job_set=taskhandle.NullJobSet()):
          job_set.started_job(str(self))
          function(self)
          job_set.finished_job()
      return call
docs: A decorator for handling `taskhandle.JobSet`\s
  
      A decorator for handling `taskhandle.JobSet`\s for `do` and `undo`
      methods of `Change`\s.