I have fixed some minor typos in 1-tuples-are-immutable-sequences.py and 4-challenge-list-of-lists.py. I have also added comments to 7-challenge-capital-city-loop.py as well as two of the "cats with hats" challenges.

9a-challenge-cats-with-hats.py was also accessing the list of cats using the cats name (line 15) from outside of the function instead of the array_of_cats parameter which was provided to the function, which could cause confusion when reading the code. I went ahead and changed that to the parameter name from the function signature for better clarity.