Challenge 1: Add a delete Command — Possible Solution
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# added to the subparsers section:
delete_parser = subparsers.add_parser("delete")
delete_parser.add_argument("id", type=int)

# added to the if/elif chain:
elif args.command == "delete":
    tasks = [t for t in tasks if t.id != args.id]
    storage.save(tasks)
    print(f"Deleted task {args.id}")

WHY THIS WORKS AS AN ANSWER
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delete_parser = subparsers.add_parser("delete") followed by
delete_parser.add_argument("id", type=int) reuses the chapter's own
complete_parser setup exactly — same shape, same type=int conversion
so args.id arrives as a real integer rather than a string, matching
the id: int type hint on the Task dataclass itself.

tasks = [t for t in tasks if t.id != args.id] reuses the list
comprehension pattern from Course 1/Course 2's comprehension chapters
to build a NEW list containing every task except the one matching
args.id — filtering by exclusion rather than manually finding an
index and calling .pop() or .remove(), which keeps the logic a single
readable expression, following the same list-filtering style already
used throughout this chapter's own list handling.

storage.save(tasks) reuses the exact same save() call from the add and
complete branches — regardless of which command ran, the same
TaskStorage.save() method persists whatever the current in-memory
tasks list looks like back to disk, keeping all three commands
consistent in how they commit changes.

Reassigning the tasks variable directly (rather than mutating it in
place) works correctly here because tasks was loaded fresh via
storage.load() earlier in main() and isn't referenced anywhere else
in the function — there's no aliasing concern like the one Course 2,
Chapter 1's mutable-class-attribute warning described.