code: def fromJob(cls, job, command, predecessorNumber):
          
          return cls(jobStoreID=None,
                     requirements=job._requirements,
                     command=command,
                     jobName=job.jobName,
                     unitName=job.unitName,
                     displayName=job.displayName,
                     predecessorNumber=predecessorNumber)
docs: Build a job node from a job object
          :param toil.job.Job job: the job object to be transformed into a job node
          :param str command: the JobNode's command
          :param int predecessorNumber: the number of predecessors that must finish
              successfully before the job can be scheduled
          :return: a JobNode object representing the job object parameter
          :rtype: toil.job.JobNode