code: def flat_node_and_edge(nodes):
      """flat_node_and_edge"""
      nodes = list(set(traverse(nodes)))
      return nodes
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from __future__ import unicode_literals
  from __future__ import absolute_import
  from dataloader.base_dataloader import BaseDataGenerator
  from utils.to_undirected import to_undirected
  import ssl
  from pgl.contrib.ogb.nodeproppred.dataset_pgl import PglNodePropPredDataset
  from pgl.sample import graph_saint_random_walk_sample
  from ogb.nodeproppred import Evaluator
  import tqdm
  from collections import namedtuple
  import pgl
  import numpy
  import copy
label_desc: Use image node_id 2 for calling a global function with example usage: flat_node_and_edge(nodes) and returns: nodes