I faced this problem in chapter 8 on page 126 under the "rviz" headline on line 6. Here a node named "keys_to_teleop_with_rates.py" is mentioned, which is necessary to create an environment to learn the basics of Rviz, but this node is not present anywhere in the entire book. This creates a vacuum because a reader cannot go further without understanding and practicing this basic skill. The main difficulty this error poses is that one cannot interact with the global variables of rviz. Specifically, I am having difficulty setting up my fixed frame according to the book.
I tried replacing the above-mentioned node with the four nodes present in the same book in the same chapter, which have very similar names, but still I am stuck at the same place.