is::applyCreateRestrictions

static function applyCreateRestrictions(&$id, &$parentId)
{
	$id = 			Assert::expectIntegerPositive($id, '$id');
	$parentId = 	Assert::expectIntegerNonNegative($parentId, '$parentId'); // parent id might be equal to 0

	if(static::checkLinkExists($id, $parentId))
	{
		throw new TreeLinkExistsException(false, array('NODES' => array($id, $parentId)));
	}
}