Extracting PDF page ranges using pdftk

I needed to extract parts of a big PDF file today, learned about the existence of pdftk, a command-line interface tool for manipulating PDFs:

https://askubuntu.com/questions/221962/how-can-i-extract-a-page-range-a-part-of-a-pdf

Conveniently, it can be installed using sudo snap install pdftk. I wanted to combine multiple page ranges of my big PDF file, so a note-to-self then:

$ pdftk foo.pdf cat 39-43 46-47 50 output bar.pdf