Exercise 1: Reading screen -ls — Possible Solution
====================================================

Commands:

  screen             # unnamed session, then Ctrl-a d
  screen -S web      # then Ctrl-a d
  screen -S db       # then Ctrl-a d
  screen -ls

Example output (your PIDs, dates and paths will differ):

  There are screens on:
          31022.db                   (27/09/26 11:04:10)   (Detached)
          31010.web                  (27/09/26 11:03:55)   (Detached)
          30998.pts-0.myserver       (27/09/26 11:03:40)   (Detached)
  3 Sockets in /run/screen/S-philip.

Reading each line:

  31022.db              PID 31022, name "db", Detached
  31010.web             PID 31010, name "web", Detached
  30998.pts-0.myserver  PID 30998, no name given, so screen used the
                        terminal (pts-0) and hostname (myserver);
                        Detached

WHY THIS WORKS AS AN ANSWER
------------------------------
It breaks every ID into its parts, and shows why the unnamed session
has a longer, less meaningful ID — a good argument for always using -S.