PhpSpreadsheet/tests/data/Calculation/TextData/LOWER.php

<?php

return [
    [
        'AbCdEfGhI',
        'abcdefghi',
    ],
    [
        'MARK BAKER',
        'mark baker',
    ],
    [
        true,
        'true',
    ],
    [
        false,
        'false',
    ],
];