Some cells are "hidden" in the google colab notebooks

looking at the [second week's episode](https://colab.research.google.com/github/brainhack-uiowa/python-novice-inflammation-colab/blob/master/02-analyzing-patient-data.ipynb#scrollTo=PZhtfhtcdmFk), it appears several cells are hidden, I do not have time to debug this, but if someone else could investigate and fix, it would make it less likely participants would skip over material.