code: def __init__(self, n_users, n_items, k, lambda_u, lambda_v, lr, U, V):
      self.n_users = n_users
      self.n_items = n_items
      self.lambda_u = lambda_u
      self.lambda_v = lambda_v
      self.lr = lr  # learning rate
      self.k = k  # latent dimension
      self.U_init = tf.constant(U)
      self.V_init = tf.constant(V)
  
      self._build_graph()
  
label_desc: Use image node_id 1 to create a new Model object  with example: obj = Model(n_users, n_items, k, lambda_u, lambda_v, lr, U, V)