final public function build($part, $type=null, $arg=null, &$text=null, &$entity=null)
	{
		if (!isset($type))
		{
			$text .= $part;
			return;
		}
		switch ($type)
		{
			case "mention":
			case "hashtag":
			case "cashtag":
			case "bot_command":
			case "url":
			case "email":
			case "phone_number":
			case "bold":
			case "italic":
			case "underline":
			case "strikethrough":
			case "code":
			case "pre":
			case "text_link":
			case "text_mention":
				$item = [];
				$item['type'] = $type;
				$item['offset'] = mb_strlen($text, 'UTF-16');
				$item['length'] = mb_strlen($part, 'UTF-16');
				switch ($type)
				{
					case "pre":
						$item['language'] = $arg;
						break;
					case "text_link":
						$item['url'] = $arg;
						break;
					case "text_mention":
						$item['user'] = $arg;
						break;
				}
				if (!isset($entity)) $entity = [];
				$entity[] = $item;
				$text .= $part;
				break;
			default:
				$text .= $part;
				break;
		}
	}