Since we've said `headers: true` above, it's possible to dereference cells with the string of the header, e.g. `row['Old URL']`. Can we do that? We've got a lot of `row[0]` and `row[5]` kicking around and it adds a bit of overhead to later understanding. If that's not possible, can we assign to variables once at the top of the block or have constants for the row indices?