def _add_boundary_comps(self):
        self.add_node('#in', comp=True)
        self.add_node('#out', comp=True)

        for node, data in self.nodes_iter(data=True):
            if 'boundary' in data:# and 'basevar' not in data:
                if data['iotype'] == 'in':
                    self.add_edge('#in', node)
                elif data['iotype'] == 'out':
                    self.add_edge(node, '#out')

        return self
Add fake boundary components and connect them to boundary
dataset/ETHPy150Open OpenMDAO/OpenMDAO-Framework/openmdao.main/src/openmdao/main/depgraph.py/DependencyGraph._add_boundary_comps