class_docstr: Standard Variational Autoencoders (VAE) for Collaborative Filtering implementation.
docstr: Returns the list of NDCG@k at each epoch.
code: def ndcg_per_epoch(self):
      """Returns the list of NDCG@k at each epoch."""
  
      return self.val_ndcg
  
imports: import numpy
  import matplotlib.pyplot
  import seaborn
  import tensorflow
  from tensorflow.keras.layers import *
  from tensorflow.keras.models import Model
  from tensorflow.keras.losses import binary_crossentropy
  from tensorflow.keras import backend
  from tensorflow.keras.callbacks import ReduceLROnPlateau, Callback
  from recommenders.evaluation.python_evaluation import ndcg_at_k
label_desc: Use image node_id 10 for calling the StandardVAE obj's underlying member method code with example usage: obj.ndcg_per_epoch() and returns: self