/**
 * @var \Smpl\Utils\Contracts\Supplier<\Smpl\Collections\Contracts\Collection<array-key, E>>|iterable<E>
 * @noinspection PhpDocFieldTypeMismatchInspection
 */
private Supplier|iterable $elementSupplier;

/**
 * @return iterable<E>
 *
 * @throws \Smpl\Collections\Exceptions\InvalidArgumentException
 */
protected function getElements(): iterable
{
    $elements = $this->elementSupplier;

    if ($elements instanceof Supplier) {
        $elements = $elements->get();
    }

    if (! is_iterable($elements)) {
        throw InvalidArgumentException::invalidElementSupplier(static::class);
    }

    return $elements;
}