Consider using a library for common functions and classes

[svenvanderburg]

Some inpiration from https://d2l.ai/:

To avoid unnecessary repetition, we capture some of our most frequently imported and used functions and classes in the d2l package. Throughout, we mark blocks of code (such as functions, classes, or collection of import statements) with #@save to indicate that they will be accessed later via the d2l package. We offer a detailed overview of these classes and functions in Section 23.8. Thed2l package is lightweight and only requires the following dependencies: