code: func (j *Job) Cancel() error {
  	if err := j.setStatus(StatusCancelled); err != nil {
  		return err
  	}
  	return nil
  }
docs: // Cancel cancels the job, but does not remove it from the database. It will be
  // added to a list of cancelled jobs. If you wish to remove it from the database,
  // use the Destroy method. Attempting to cancel a destroyed job will have no effect.