def add_parent(self, parent):
        assert isinstance(parent, TreeNode)
        if parent not in self.parents:
            self.parents.append(parent)
Test availibility of Ganeti commands.
dataset/ETHPy150Open VisTrails/VisTrails/contrib/titan/class_tree.py/TreeNode.add_parent--crossover with--dataset/ETHPy150Open ganeti/ganeti/qa/qa_env.py/TestGanetiCommands