def isRoot(self, itemId):
        return self.items.isRoot(itemId)
Writes `domain` to `grid_file` and `f_file` in Plot3D format.
dataset/ETHPy150Open rwl/muntjac/muntjac/ui/tree.py/Tree.isRoot--crossover with--dataset/ETHPy150Open OpenMDAO/OpenMDAO-Framework/openmdao.lib/src/openmdao/lib/datatypes/domain/plot3d.py/write_plot3d_f