def graph_add_node(self, node_object):
        """Adds a station or cable distributor object to grid graph if not already existing
        
        Parameters
        ----------
        node_object : GridDing0
            Description #TODO
        
        """
        if ((node_object not in self._graph.nodes()) and
            (isinstance(node_object, (StationDing0,
                                      CableDistributorDing0,
                                      LVLoadAreaCentreDing0,
                                      CircuitBreakerDing0,
                                      GeneratorDing0)))):
            self._graph.add_node(node_object)