Listing 17-31 is marked as "does not compile"

[mkauf]

URL to the section(s) of the book with this problem: https://rust-book.cs.brown.edu/ch17-04-streams.html

Description of the problem: Listing 17-31 is marked with "This code does not compile!", but it does. (Listing 17-31: Successfully using an iterator as the basis for a stream)

Suggested fix: Remove the symbol that means "This code does not compile"