Unknown and unclear code in section about "debdiff"

Dear Mechthild, I was reading through the German (original?) version of your book. In the PDF it is section 35.6.

https://salsa.debian.org/ddp-team/dpb/-/blob/master/Part3.nw#L9037

I don't understand the section. You write about debdiff and other tools. But I never see how to call it on the shell. On the other hand there are two code blocks in that section. The blocks do miss an introduction or a caption. It is not clear what language that code is written in. I guess it is Bash? But please don't expect your readers figuring this out them self. Not everyone do (have to) use Bash.

While reading threw the text blocks it is not clear why the code blocks are there. What is there purpose?

In the end I don't understand how to check the file "debian/copyright".

Kind Christian