function test(): void {
    $a = vec[1, 2, 3];

    unset $a[0];
    unset ($a[0]);
    unset ($a[0], $a[0]);
    unset ($a[0], $a[0], $a[0]);

    isset $a[0];
    isset ($a[0]);
    isset ($a[0], $a[0]);
    isset ($a[0], $a[0], $a[0]);

    $a = dict['a' => 1, 'b' => 2, 'c' => 3];

    unset $a['a'];
    unset ($a['a']);
    unset ($a['a'], $a['a']);
    unset ($a['a'], $a['a'], $a['a']);

    isset $a['a'];
    isset ($a['a']);
    isset ($a['a'], $a['a']);
    isset ($a['a'], $a['a'], $a['a']);
}