Aha have found these music notebooks I have mentioned some days ago. I'm not a musician, didn't test them, so I don't know if they are worthy.

Here the webpage with all the notebooks:

https://magenta.tensorflow.org/demos/colab/

And this one, that I think is some kind of merge of 3 notebooks from the same webpage, but is not listed on it:

https://colab.research.google.com/notebooks/magenta/hello_magenta/hello_magenta.ipynb