code: def prepare_training(self):
      self.log_prob = []
  
imports: import os
  import dgl
  import torch.nn
  import torch
  from functools import partial
  import torch.nn.functional
  from torch.distributions import Bernoulli
  from torch.distributions import Categorical
  import torch.utils.model_zoo
label_desc: Use image node_id 3 for calling the AddNode obj's underlying member method code with example usage: obj.prepare_training() without return types