I have some comments for typos in notebook. The exercise numbers and the solution number are mismatched. Also there is typo like the one in Chapter 4: understanding services
Solution for Exercise 4.2
The command mentioned for running the service call has extra backslash
ros2 service call /moving_right std_srvs/srv/SetBool data:\ true\
Would request developers to look into this as this might cause confusion since with this extra character simulation was not working.
I understand its difficult to review the notebooks as things get updated. I would suggest something like how Wikipedia is maintained. Maybe someone can edit and get it reviewed and this way notebooks will be updated regularly and free from erros. If any supprt required I am willing to help