The first example in the "Sorting in Practice" section appears to be broken. The text makes it seem like the list should be sorted in-memory and then written to disk sorted, but the example un-sorts the list when it's written to disk.
Edit: the flush example (2nd one) in the recap section does the same thing, when the text says that the records are supposed to be written to the file in sorted order.
Edit: the flush example (2nd one) in the recap section does the same thing, when the text says that the records are supposed to be written to the file in sorted order.