Method demo

examples/demo.php:644–666

@param list $pens */

(array $pens)

{
    /** @param list<Pen> $pens */
    public function demo(array $pens): void
    {
        // Pattern 1: null-init + foreach reassignment + truthiness guard
        $found = null;
        foreach ($pens as $pen) {
            if ($pen->color() === 'blue') {
                $found = $pen;
            }
        }
        if ($found) {
            $found->write();                      // Pen from foreach reassignment
        }

        // Pattern 2: null-coalesce + guard inside foreach
        /** @var array<string, Pen> $lookup */
        $lookup = getUnknownValue();
        $keys = ['a', 'b'];
        foreach ($keys as $key) {
            $item = $lookup[$key] ?? null;
            if (!$item) { continue; }
            $item->write();                       // Pen from array access via coalesce
        }
    }
}