Challenge 3: is vs is_deeply — Possible Solution
====================================================================

use strict;
use warnings;
use Test::More;

my $array1 = [1, 2, 3];
my $array2 = [1, 2, 3];

is($array1, $array2, 'is() comparing two separate arrayrefs');
is_deeply($array1, $array2, 'is_deeply() comparing the same two arrayrefs');

done_testing();

Predicted results:
is($array1, $array2, ...) -> FAILS. Both are arrayrefs pointing to
DIFFERENT underlying arrays in memory, even though those arrays
happen to contain identical values — is() only checks whether the
two references ARE the same reference, per this chapter's own
warn-box.

is_deeply($array1, $array2, ...) -> PASSES. It recursively compares
the actual CONTENTS of the two arrayrefs (1, 2, 3 vs 1, 2, 3) rather
than their identity, so two separately-built structures with matching
contents are correctly reported as equal.

One-sentence explanation of why they disagree:
is() compares reference IDENTITY (are these literally the same object
in memory), while is_deeply() compares reference CONTENTS
(recursively, do these hold the same values), so two independently
created references holding identical data will always pass
is_deeply() while failing a plain is() check.

WHY THIS WORKS AS AN ANSWER
------------------------------
$array1 and $array2 reuse Course 1, Chapter 9's own anonymous-array-
reference syntax, deliberately built as two SEPARATE [1, 2, 3]
literals rather than one array reference assigned to two variable
names — this is what guarantees they are genuinely different
references in memory despite matching contents, exactly the scenario
this chapter's own warn-box describes.

The predicted is() failure and is_deeply() success reuse the
chapter's own explanation of the distinction directly — "is() on
References Checks Identity, Not Contents" and "is_deeply() is the
correct tool for comparing the actual contents" — applied here to
arrayrefs specifically, generalizing the chapter's own hashref
example to a second reference type covered earlier in the course.