GuzzleHttp\Tests\Psr7\UriNormalizerTest::getUnreservedCharacters PHP Method

    public function getUnreservedCharacters()
    {
        $unreservedChars = array_merge(range('a', 'z'), range('A', 'Z'), range('0', '9'), ['-', '.', '_', '~']);
        return array_map(function ($char) {
            return [$char];
        }, $unreservedChars);
    }