def fromJobNode(cls, jobNode, jobStoreID, tryCount):
        """
        Builds a job graph from a given job node
        :param toil.job.JobNode jobNode: a job node object to build into a job graph
        :param str jobStoreID: the job store ID to assign to the resulting job graph object
        :param int tryCount: the number of times the resulting job graph object can be retried after
            failure
        :return: The newly created job graph object
        :rtype: toil.jobGraph.JobGraph
        """
        return cls(command=jobNode.command,
                   jobStoreID=jobStoreID,
                   remainingRetryCount=tryCount,
                   predecessorNumber=jobNode.predecessorNumber,
                   unitName=jobNode.unitName, jobName=jobNode.jobName,
                   **jobNode._requirements)