SliceConverter::sanitize

static function sanitize($string)
{
	if (!self::isValid($string))
	{
		return BlockSanitizer::clean($string);
	}

	$content = self::toArray($string);
	$list = $content->getList();
	foreach ($list as $index => $item)
	{
		if ($item['type'] !== BlockContent::TYPE_BLOCKS)
		{
			continue;
		}

		$item['value'] = BlockSanitizer::clean($item['value']);
		$list[$index] = $item;
	}

	$content->setList($list);
	return self::toString($content);
}