Keras Introduction and Tensorflow Introduction Notebooks

I’ve seen both a Keras Introduction Notebook and a Tensorflow Introduction mentioned, but where do I find them?

TensorFlow was introduced in Course 2 Week 3.
I don’t recall specifically about Keras.

Well, that Tensorflow introduction is not overly helpful later on, it’s mostly talking about the tape feature which was not needed until Course 4 Week 1.

A Keras Introduction Notebook is mentioned in Course 4 Week 1, but I didn’t see one.