This website is first of all a private one.
Much of the content on this web site was used in the mean time for teaching purpose. Feedback was strong, leading to the current re-structuring of this web site.
‘Beautiful dataframes’ went live in early summer 2021.
At first it was meant - and still is - as a time saver. The internet seems to be the best place to find things.
Later it became a storage for teaching material.