def METHOD_NAME(graph): 
    '''add_self_loop_for_subgraph
    '''
    self_loop_edges = np.zeros((graph.num_nodes, 2))
    self_loop_edges[:, 0] = self_loop_edges[:, 1] = np.arange(graph.num_nodes)
    edges = np.vstack((graph.edges, self_loop_edges))
    edges = np.unique(edges, axis=0)
    g = pgl.graph.SubGraph(num_nodes=graph.num_nodes, edges=edges, reindex=graph._from_reindex)
    for k, v in graph._node_feat.items():
        g._node_feat[k] = v
    return graph