Challenge 1: A Moo Class — Possible Solution
====================================================================

package Book;
use Moo;

has 'title' => (is => 'ro', required => 1);
has 'read'  => (is => 'rw', default => sub { 0 });

package main;
use strict;
use warnings;
use feature 'say';

my $book = Book->new(title => "Perl Fundamentals");
say $book->read;    # 0

$book->read(1);
say $book->read;    # 1

Output:
0
1

WHY THIS WORKS AS AN ANSWER
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has 'title' => (is => 'ro', required => 1); reuses the chapter's own
attribute-declaration syntax exactly — is => 'ro' generates a getter
only, and required => 1 means Book->new(...) will die if title isn't
supplied, both reused directly from the chapter's own examples.

has 'read' => (is => 'rw', default => sub { 0 }); reuses is => 'rw'
to generate BOTH a getter and a setter (needed here since the
challenge requires updating it later), and default => sub { 0 }
reuses the chapter's own coderef-wrapped default pattern from its
warn-box — even though 0 is a plain immutable value here (not a
mutable reference like the warn-box's own [] example), wrapping it in
sub {...} still matches Moo's own required syntax for defaults.

Book->new(title => "Perl Fundamentals") supplies only title, leaving
read to fall back to its default (0) — say $book->read; confirms
this, printing 0. $book->read(1); reuses the generated SETTER that
is => 'rw' provides — calling the accessor WITH an argument updates
the attribute — and the second say $book->read; confirms it changed
to 1, demonstrating the read-write behavior the challenge specifically
asks for.