This week I have been involved in a book project. Second edition of our 400+ page book is getting ready, but there are all those small things which require correcting at the last moment. Sometimes it seems easier to let go, but then I just push on and re-read the thing once more. And I have also learned something. One of the new topics of the book is wavelets, and that is certainly interesting. But I don't have the time to try out in practice all those nice wavelet examples.