code: def addFollowOn(self, followOnJob):
          
          self._followOns.append(followOnJob)
          followOnJob._addPredecessor(self)
          return followOnJob
docs: Adds a follow-on job, follow-on jobs will be run after the child jobs and \
          their successors have been run.
  
          :param toil.job.Job followOnJob:
          :return: followOnJob
          :rtype: toil.job.Job