code: def log_norm_pdf(x, mu, logvar):
      return -0.5 * (
          logvar + np.log(2 * np.pi) + (x - mu).pow(2) / logvar.exp()
      )
  
imports: import numpy
  from copy import deepcopy
  import torch
  import torch.nn
  import torch.nn.functional
  from recbole.model.abstract_recommender import GeneralRecommender, AutoEncoderMixin
  from recbole.model.init import xavier_normal_initialization
  from recbole.utils import InputType
label_desc: Use image node_id 2 for calling a global function with example usage: log_norm_pdf(x, mu, logvar) and returns: unknown