Stuck in tutorial "Creating Python OOT with gr-modtool"

Thanks for providing all the documentation and tutorials.

They are really usefull for beginners like me.

I'm trying to learn and following the tutorials but I got stuck in "Creating Python OOT with gr-modtool" 

I keep facing the following error message:

"AttributeError: module 'gnuradio.customModule' has no attribute 'addSubSelect'"

Question:
I wonder if I make a mistake or is there something wrong with my (freshly installed) system setup (Ubuntu 24.10 GRC3.10.11.0) ?
Thanks in advance for helping me out, guidance, tips or tricks!

Robert

This is the complete log:
<<< Welcome to GNU Radio Companion 3.10.11.0 >>>
Block paths:
/home/robert/.local/state/gnuradio
/usr/share/gnuradio/grc/blocks
/usr/local/share/gnuradio/grc/blocks
Loading: "/home/robert/My_First-block.grc"
>>> Done
Loading: "/home/robert/Creating_Python_OOT2.grc"
>>> Done
Loading: "/home/robert/Creating_Python_OOT.grc"
>>> Done
Generating: "/home/robert/default.py"
Executing: /usr/bin/python3 -u /home/robert/default.py
QSocketNotifier: Can only be used with threads started with QThread
Traceback (most recent call last):
  File "/home/robert/default.py", line 186, in <module>
    main()
  File "/home/robert/default.py", line 163, in main
    tb = top_block_cls()
         ^^^^^^^^^^^^^^^
  File "/home/robert/default.py", line 124, in __init__
    self.customModule_addSubSelect_0 = customModule.addSubSelect(True)
                                       ^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: module 'gnuradio.customModule' has no attribute 'addSubSelect'
>>> Done (return code 1)