code: def __getitem__(self, idx):
      if torch.is_tensor(idx):
          idx = idx.tolist()
  
      node_state = self.node_state[idx, :, :]
      node_label = self.node_label[idx, :, :]
      return (node_state, node_label)
  
imports: import copy
  import os
  import dgl
  import networkx
  import numpy
  import torch
  from torch.utils.data import DataLoader, Dataset
label_desc: Use image node_id 3 for calling the MultiBodyDataset obj's underlying member method code with example usage: obj.__getitem__(idx) and returns: node_state,  node_label