Warnings In Tutorial DeepIV

I am learning about this package and going through the (very helpful) tutorial for DeepIV

I pick up a warning in cell 6, indicating:

WARNING:tensorflow:
The following Variables were used a Lambda layer's call (lambda_8), but
are not present in its tracked objects:
  <tf.Variable 'dense_10/kernel:0' shape=(2, 128) dtype=float32>
  <tf.Variable 'dense_10/bias:0' shape=(128,) dtype=float32>
  <tf.Variable 'dense_11/kernel:0' shape=(128, 64) dtype=float32>
  <tf.Variable 'dense_11/bias:0' shape=(64,) dtype=float32>
  <tf.Variable 'dense_12/kernel:0' shape=(64, 32) dtype=float32>
  <tf.Variable 'dense_12/bias:0' shape=(32,) dtype=float32>
  <tf.Variable 'dense_13/kernel:0' shape=(32, 1) dtype=float32>
  <tf.Variable 'dense_13/bias:0' shape=(1,) dtype=float32>
It is possible that this is intended behavior, but it is more likely
an omission. This is a strong indication that this layer should be
formulated as a subclassed Layer rather than a Lambda layer.

Later steps continue to work so it is just a warning, but but hopefully it can be resolved.

Start with notebooks/Deep IV Examples.ipynb and reproduce the warning in cell 6. Inspect the Lambda layer associated with the reported variables and determine the intended correction; the work is done when the warning no longer appears and the later tutorial steps still run successfully.