Unfortunately that's a guide for older GNU Radio versions. It will give new users quite a bit of trouble at this point with all the namespace changes since 3.6. But back in 2015 it was a great way to learn.
Re:GNU Radio 3.9
by marcusmueller on Tuesday January 19, 2021 @11:47AM
(#25835322)
I quite like Marc Lichtmann's (who happens to be on the GNU Radio board) https://pysdr.org quite refreshing and good for beginners.
[1] https://greatscottgadgets.com/sdr/