docs: def __addNode(self, name, cls):
          '''
          Add a node to the topology
          '''
          if name in self.nodes:
              raise Exception("A node by the name {} already exists.  Can't add a duplicate.".format(name))
          self.__nxgraph.add_node(name)
          self.__nxgraph.node[name]['label'] = name
          self.__nxgraph.node[name]['nodeobj'] = cls()
          self.__nxgraph.node[name]['type'] = cls.__name__