Тест — ключи, порядок и пропавший ключ

<?php

$stock = ['pear' => 2, 'apple' => 5];
$stock['kiwi'] = 1;
$stock['pear'] = 7;
unset($stock['apple']);
foreach ($stock as $fruit => $qty) {
    echo $fruit, '=', $qty, ' ';
}
echo count($stock), "\n";