def _delete_edges(self, features):
        """ Removes the node corresponding to each item in 'features'.
        """
        graph = self._graph

        if graph is not None:
            for feature in features:
                for graph_edge in self.factory.edges:
                    if feature.__class__ in graph_edge.edge_for:
                        tail_feature = getattr(feature, graph_edge.tail_name)
                        head_feature = getattr(feature, graph_edge.head_name)

                        graph.delete_edge( id(tail_feature), id(head_feature) )

        graph.arrange_all()
Removes the node corresponding to each item in 'features'.