Method map

examples/demo.php:3618–3621

* @return ($signature is "foo" ? Pen : Marker) */

(string $signature, mixed $source)

     * @return ($signature is "foo" ? Pen : Marker)
     */
    public function map(string $signature, mixed $source): Pen|Marker
    {
        return new Pen();
    }
}

// ┃  Everything below exists to support the demos above.               ┃