Manager::availableOnlyForZone

static function availableOnlyForZone(string $zone): bool
{
	static $available = null;

	if ($available !== null)
	{
		return $available;
	}

	$available = true;

	if ($zone === 'ru')
	{
		if (!in_array(self::getZone(), ['ru', 'by', 'kz']))
		{
			$available = false;
		}
	}

	return $available;
}