At least the text right at the beginning of the code that says what the function does. We can follow numpy style of documenting; e.g. This is my code with that style. Here is Numpy's Style guide and here is its example page.

I have added, for example, .png and .ipynb to .gitignore. Jupyter Notebooks contain plots, etc. that makes them heavy which over time makes repositories very heavy. But, in general, practice diligence for pushing stuff. For example, push plots that are PDF but do not push PDF papers. Jupytext converts Jupyter notebooks to text (.md, .py, etc.). The result looks like this. This is helpful for not pushing Jupyter notebooks to Git repositories.