def _dfs(self, visited):
        if self not in visited:
            visited.add(self)
            for successor in self._children + self._followOns:
                successor._dfs(visited)
Adds the job and all jobs reachable on a directed path from current         node to the set 'visited'.
dataset/ETHPy150Open BD2KGenomics/toil/src/toil/job.py/Job._dfs