## Chapter 10 — Twelve mailboxes are not six rows ### Learning outcomes After this chapter, you should be able to: 1. Separate six printed rows from twelve mailboxes. 2. Say which mailbox had the outside-forwarding rule. 3. Refuse a 2-of-6 fraction in place of the lines. ### 10.1 The search result is a sentence. The print is six tuples. BrightPath searched all 12 mailboxes for rules that forward to an outside address. Only Elaine's mailbox had one. The same search found no other unusual sign-ins. That result is prose. The script prints six rows and stops. It does not loop over twelve mailboxes, and it does not print the words "2 of 6" or "1 of 12". Three labels appear. `e.finch` has four rows. `s.marlow` has one row, Friday 09:10 UK, and it prints `ok`. `l.barros` has one row, Friday 08:30 UK, and it prints `ok`. Those two labels are not full names in this book, and this chapter does not invent names for them. Twelve mailboxes minus the three labels leaves nine mailboxes with no row. Those nine are not "six missing lines", because six is the length of `signins`, not a count of absent people. The colleague on holiday in Spain and the partner whose phone roamed are first-month alert explanations. They are not `s.marlow` and not `l.barros`. Merging those later alerts into the Friday rows would invent an identity the file does not store. | Count | What it counts | |---|---| | 6 | Tuples in `signins` | | 3 | Distinct labels in those tuples | | 12 | Mailboxes in the prose search | | 1 | Mailbox with an outside-forwarding rule | | 9 | Mailboxes with no printed row | ### 10.2 Worked example | Offered rewrite | Why it fails or stands | Decision | |---|---|---| | Six lines remain the print | The list length is six | Keep | | Only Elaine's mailbox had the rule | Prose search | Keep, as prose | | "The lab found 2 of 6 attacks." | The file prints no such fraction | Refuse | | "s.marlow is the Spain holiday." | Different facts, no shared identity | Refuse | > **Synthetic case.** Nine mailboxes stay unnamed. ### Errors and limits Do not lengthen the list to twelve so the search looks like output. ### Apply - **EX056 — Two counts.** A classmate writes "2 of 6" on the print and says the other ten mailboxes were the ok rows. How many rows does the script print, how many mailboxes were searched, and whose mailbox had the outside-forwarding rule? *Rubric:* 3 = six rows; twelve mailboxes in prose; only Elaine's rule; `s.marlow` and `l.barros` stay ok rows; do not print 2 of 6;; 2 = six rows and twelve mailboxes stay apart;; 1 = one count;; 0 = none. ### Continue studying — lesson 10 (chapter 10 of 20) [← Chapter 09](#ch-09) · [Course chapter index](../SUBJECTS.md) · [Chapter 11 →](#ch-11) Continue to the next authored lesson. ## Worked answers **EX056.** The script prints six rows. Twelve mailboxes were searched in prose. Only Elaine's mailbox had the outside-forwarding rule. `s.marlow` and `l.barros` stay ok rows. Do not print 2 of 6.