Comment by Thorrez

This comment seems wrong to me:

      // The "indirect" pointer points to the
      // *address* of the thing we'll update

The "indirect" pointer points to the thing we'll update. See at the bottom, it's updating *indirect, so "indirect" points to the thing being updated. On the other hand, "indirect" points to the address of the thing we'll remove. There's a specific item being removed, and there's a specific thing that will be updated; the thing being updated comes immediately before the thing being removed; they're not the same thing.