It's there, in Shared bindings: "Alt+L lists the contents of the current directory, unless the cursor is over a directory argument, in which case the contents of that directory will be listed."
The book that includes the results from these slides has broader scope, and also can be downloaded for free from arXiv: https://www.maths.ed.ac.uk/~tl/ed/
"The starting point is the connection between diversity and entropy. We will discover:
• how Shannon entropy, originally defined for communications engineering, can also be understood through biological diversity (Chapter 2);
• how deformations of Shannon entropy express a spectrum of viewpoints on the meaning of biodiversity (Chapter 4);
• how these deformations provably provide the only reasonable abundance-based measures of diversity (Chapter 7);
• how to derive such results from characterization theorems for the power means, of which we prove several, some new (Chapters 5 and 9).
Complementing the classical techniques of these proofs is a large-scale categorical programme, which has produced both new mathematics and new measures of diversity now used in scientific applications. For example, we will find: [...]"
"The question of how to quantify diversity is far more mathematically profound than is generally appreciated. This book makes the case that the theory of diversity measurement is fertile soil for new mathematics, just as much as the neighbouring but far more thoroughly worked field of information theory"
pushd/popd are intended for interactive use, not for use in scripts. It prints the full stack on directories and there is no option to be quiet. Of course, there is always redirecting to /dev/null but it is intentional to not have option to be quiet.
Usually there is no need to return to original directory. Change of directory is process-local (script-local) so the calling process is not affected by this 'cd' in the script.
My choice would be the recently standardized JPEG XL designed to replace all of: JPEG, JPEG 2000, PNG, GIF. Among other things, it is supposed to be the first choice for long-term storage. I guess mass adoption will begin after including it in the PDF standard. It is already experimentally in Chrome and Firefox.