"To solve the puzzle presented and discussed in Part 3 of this series, as well as similar puzzles, I have to figure out how to code Step 2.6 in Python. (See Part 3 for an outline of all the steps in this problem-solving exercise.) The code should be straightforward, except for saving (Step 2.6.1) and restoring (Step 2.6.4) values of compound data structures.
"In fact, this part of the code turned out to be harder to write than I expected. A list of my mistakes can be seen below in Appendix B, but the important lesson is this: simply assigning a list doesn't copy it, as Learning Python says. Instead, another reference is created to the same list..."
