In Section 15 (Blocks, Procs, and Lambdas), Part 13 (Lambda Syntax), there is an error in one of the strings. Both the renaissance painter and the turtle are named michelangelo rather than michaelangelo.
strings = ["leonardo", "donatello", "raphael", "michaelangelo"]
should become
strings = ["leonardo", "donatello", "raphael", "michelangelo"]